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The 6th International Conference
on Bacterial Blight of Rice
Program and Abstract Book
Can Tho city, Vietnam
19-21 August 2019
The 6th International Conference on Bacterial Blight of Rice
The 6th International Conference on Bacterial Blight of Rice
“Together Towards a Sustainable Management of Bacterial Blight and Bacterial Leaf Streak of Rice”
Program and Abstract Book
Can Tho city, Vietnam
19-21 August 2019
The 6th International Conference on Bacterial Blight of Rice
Table of Contents
Sponsors............................................................................................................................................................. 1
Opening Remarks from Vice Minister, MARD ..................................................................................... 2
A Message from the Conference Organizers ........................................................................................ 4
About the Organizers .................................................................................................................................... 5
Executive Committee .................................................................................................................................... 6
Keynote Speakers’ Biography .................................................................................................................... 7
Conference Program ..................................................................................................................................... 9
Keynote Speech Abstracts: ...................................................................................................................... 13
Oral Presentations’ Abstracts ................................................................................................................. 17
Session I: Current Assessment of Bacterial Blight Disease ..................................................... 17
Session II: Epidemiology and Population Biology of Bacterial Blight ................................ 20
Session III: Host Resistance: Genetics and Molecular Biology .............................................. 23
Session IV: Disease Management and Breeding .......................................................................... 30
Session V: Molecular Interaction Between Host and X. oryzae pv. oryzae ........................ 40
Session VI: Integrative Genomics, Proteomics – Effectors, Epigenetics of Xoo ............... 46
Session VII: Biotech and Genome/Gene Editing ......................................................................... 49
Poster Presentations’ Abstracts ............................................................................................................. 51
ICBB06 List of Participants ...................................................................................................................... 68
General Information ................................................................................................................................... 76
Venue Maps .................................................................................................................................................... 80
The 6th International Conference on Bacterial Blight of Rice
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Sponsors
Vietnam Ministry of
Agriculture and Rural
Development
Cuu Long Delta Rice
Research Institute
Bayer Vietnam Ltd.
Binh Dien
Fertilizer Joint
Stock Company
Dong Nam Seed Joint Stock
Company
Institut de recherche pour
le développement
The 6th International Conference on Bacterial Blight of Rice
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Opening Remarks from Vice Minister, MARD
Distinguished Guests, Speakers, Sponsors, and Friends!
Welcome you All to Can Tho City of Viet Nam and to the 6th International
Conference on Bacterial Blight of Rice!
I am so pleased to see so many colleagues, professors, and friends from many
countries. This conference provides the opportunity for all of us to discuss and share
achievements and progress in studying bacterial blight and related subjects in rice.
As you know, global rice production has increased faster over the last decade and
most of the increase in rice production was due to higher yields. According to the
Food and Agricultural Organization (FAO) report, world rice production is estimated
to amount to 516.8 million tons (milled basis) in 2019, unchanged from the 2018 all-
time high. Under current prospects of rice production, global rice production will
remain the same in 2020. Vietnam is the world’s fifth-largest rice-producing country
and in the top 3 rice exporting countries in the world. FAO forecasts the 2019
Vietnam’s rice production at 28.3 million tons (milled basis), slightly decreased from
the previous year’s record level. However, there are some factors such as global
warming, environmental crisis, plant diseases and pests, including biofuel needs that
affect rice production in many countries, including Vietnam.
Bacterial blight is one of the most serious diseases of rice. The major effect of
bacterial blight disease on rice production is yield loss. The estimated yield losses due
to bacterial blight in tropical Asia vary from 2 to 74%, depending on location, season,
weather, crop growth stage, and cultivar. Globally, the effect of bacterial blight
disease in rice has been reported from different parts of the world from Asia to
northern Australia, Africa, and the United States. According to the report of Vietnam
Ministry of Agriculture and Rural Development (MARD), bacterial blight disease
negatively affected two major rice production areas, the Mekong and Red River
Deltas. In 2016, of 150.000 ha total bacterial blight affected areas, 19.045 ha were
severely yield loss countrywide. Whereas, 51.000 ha were damaged by this disease in
the southern provinces including the Mekong Delta, the largest rice production area in
Vietnam, contributing 54% of the country’s rice output and up to 90% of rice exports.
Thus, achievements and progress in studying of bacterial blight will be useful for
disease management and increasing rice production further.
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It is a great honor and pleasure for us to hold the 6th International Conference on
Bacterial Blight in Can Tho city, the center of Mekong Delta. We hope this
conference will open new opportunities for cooperation in studying bacterial blight
and other related projects.
Through this conference, we would like to thank sponsors and organizations for your
support and help.
Enjoy your participation in the 6th International Conference on Bacterial Blight and
memorable time visiting Can Tho city.
Thank you for your attention and I wish you a very successful conference.
Le Quoc Doanh
Vice Minister
Vietnam Ministry of Agriculture and Rural Development
The 6th International Conference on Bacterial Blight of Rice
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A Message from the Conference Organizers
Distinguish Guests, Ladies and Gentlemen!
Welcome to Viet Nam and Can Tho city for the 6th International Conference on
Bacterial Blight of Rice.
Like the previous conference in the Philippines, we are confident that the 6th
International Conference on Bacterial Blight of Rice in 2019 will provide a forum for
fruitful interaction and exchange of ideas between the participants coming from
around the world.
Bacterial blight is the most important bacterial disease in rice which can cause up to
74% of yield loss due to its high epidemic potential. This year, we are glad to note that
15 different countries from around the world are represented by the authors and
participants, thereby making it a truly international event. The technical program
covers three days of presentations including three keynote speeches, 33 oral
presentations and 17 posters, and a field trip to CLRRI. So, we expect you to have a
great time during these three days.
No conference can be successful without excellent teamwork and ours is no different.
Our special appreciations also go to the sacrifices and perspirations of our colleagues
at CLRRI and the all local committee members in making this conference a smooth
process.
I would like to thank the members of the international organizing committee, the
speakers, and the presenters, who have made so many efforts for the preparation of
their latest researches and the keynote speakers who kindly accepted sharing their
expertise with the attendees.
I would like to sincerely thank the many sponsors who made the 6th International
Conference on Bacterial Blight of Rice possible. Without their support, the conference
would not be financially viable for members.
Most of all, thank you for attending ICBB06 2019. We hope this conference will
benefit all of us in advancing research activities and building new friendship.
I hope you enjoy the conference and Can Tho city.
Tran Ngoc Thach
Chair, Local Organizing Committee
The 6th International Conference on Bacterial Blight of Rice
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About the Organizers
The Cuu Long Delta Rice Research Institute (CLRRI) is the premier national institute
specialized in rice research and education, headquartered in Can Tho city, the center
of the Mekong delta of Vietnam. The institute, founded in 1977 by the Vietnamese
government, is the major force in Vietnam agricultural science and plays a leading
position in the nation as a dynamic source for innovative research and teaching.
CLRRI works closely with industry, business and public research bodies nationally
and internationally to ensure its programs are relevant to today’s fast-paced and ever-
changing world. The primary functions of the institute are as follow: i) To carry out
basic and applied research in all disciplines of rice, rice-based crops, and agricultural
systems in the Mekong Delta region towards sustainable agriculture; ii) To set up and
implement research programs in collaboration with national and international
organizations in rice research and rice-based farming systems; iii) To transfer
scientific and technical advances in agriculture to public and private sectors; and iv)
To train nationwide agro-technical staffs and farmers to produce and supply rice seed
stock. Over 42 years of the establishment, more than 180 new varieties have been
developed by CLRRI and released to farmers under the name OM rice variety. More
than 70% of about 4,2 million hectares of total rice-growing area annually in the
Mekong delta has been covered by the OM rice varieties in the last decade. The
institute has also developed and introduced new and improved methods and
technologies to farmers for sustainable and profitable management of their crops.
Besides, OM rice varieties have also been grown in different countries in Asia, Africa,
and Latin America.
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Executive Committee
International Committee
▪ Dr. Le Quoc Doanh, Vice Minister, Ministry of Agriculture and Rural
Development (MARD), Vietnam
▪ Dr. Nguyen Hong Son, President, Vietnam Academy of Agricultural
Sciences, Vietnam
▪ Dr. Wolf B. Frommer, Institute for Molecular Physiology,
HHU, Düsseldorf, Germany
▪ Dr. Jan E. Leach, Colorado State University, USA
▪ Dr. Ralf Koebnik, Director of Research, Institute of Research for
Development, France
▪ Dr. Adam J. Bogdanove, Cornell University, USA
▪ Dr. Jagjeet Singh Lore, Punjab Agricultural University, India
▪ Dr. Chenyang He, Chinese Academy of Agricultural Sciences, China
▪ Dr. Ricardo Olivera, International Rice Research Institute
▪ Dr. Gongyou Chen, Shanghai Jiaotong University, China
▪ Dr. Lin-Woo Kang, Konkuk University, South Korea
Local Organizing Committee
▪ Dr. Tran Ngoc Thach, CLRRI (Chair)
▪ Dr. Huynh Van Nghiep, CLRRI
▪ Dr. Nguyen Thuy Kieu Tien, CLRRI
▪ Dr. Hoang Dinh Dinh, CLRRI
▪ Dr. Duong Hoang Son, CLRRI
▪ Dr. Nguyen Thi Phong Lan, CLRRI
▪ Dr. Nguyen The Cuong, CLRRI
▪ Ms. Nguyen Thi Khao, CLRRI
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Keynote Speakers’ Biography
Dr. Casiana Vera Cruz
Dr. Casiana M. Vera Cruz or "Nollie" is recognized for her
important contributions in the field of plant pathology (Senior
Scientist II) at the Host Plant Resistance Cluster, Rice Breeding
Platform at the International Rice Research Institute. With
expertise in plant pathology, she was responsible for researches on
pathogen biology, especially her early work on bacterial blight of
rice, population biology, host-pathogen interaction, and host plant
resistance to diseases. She developed and refined molecular
markers for both Xoo and rice R genes and has contributed to
resistance improvement to BB and other diseases in different rice
ecosystems in collaboration with breeders. She also led the IRRI-
DA Heirloom Rice Project which aims to raise productivity and
enrich the legacy of traditional rice through empowering
communities in unfavorable rice-based ecosystem. Currently, she
is engaged in coordination of IRRI research portfolio for the
Philippines.
Professor Jan Leach
Prof. Jan Leach is a plant pathologist who studies the
molecular basis of plant disease susceptibility and resistance
and how these responses are influenced by interactions
within the phytobiome. Prof Leach is the current President of
the International Society of Plant Pathology. She is a Fellow
and a past President of the American Phytopathological
Society (APS). She served on the APS Public Policy Board
for 16 years, leading advocacy efforts such as the
Phytobiomes Initiative, a systems-level approach to
improving crop productivity. Prof Leach is a Fellow of the
American Association for the Advancement of Science
(AAAS) and a Fellow of the American Academy of
Microbiology. She is a member of the Board on Agriculture
and Natural Resources of the US National Academy of
Sciences, and a Non-Resident Fellow of the Noble Research
Foundation Institute. Recently, Prof. Leach has received
the Agropolis Louis Malassis International Scientific Prize
for Agriculture and Food in Montpelier, France, during
the 4th World Congress on Agroforestry in May.
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Professor Wolf B. Frommer
Dr. Wolf B. Frommer is Professor and Head of the Institute
for Molecular Biology, Heinrich Heine
University Düsseldorf 2017 - present). He earned his Ph.D.
in Biology with Peter Starlinger at the University of Cologne
in 1987 and was an Independent group leader at the Institute
for Genebiological Research in Berlin. His lab pioneered the
development of metabolite sensors (e.g. sugars, amino
acids), hormones (ABA, gibberellin) and reporters of
transporter activity (ammonium, nitrate and peptide
transporters). A recent development is the Matryoshka
concept that enables ratiometric measurements with single-
fluorophore sensors. His lab was also the first to identify and
characterize the role many of the the key transporters from
plants (sucrose, amini acids, ammonium, peptides,
nucleobases) and is developing plants that are resistant to
pathogens. Recent recognitions include the Laurence
Bogorad Award for Excellence in Plant Biology, 2012,
election to the German National Academy of Sciences
Leopoldina, 2015, the Alexander von Humboldt
Professorship – International Prize for Research in Germany,
2016 and the Tsungming Tu award 2018.
The 6th International Conference on Bacterial Blight of Rice
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Conference Program
Monday - August 19, 2019 (Day 1)
07:30 Registration Local Organizer
08:30 Opening Remarks Dr. Le Quoc Doanh
Vice Minister, MARD, Vietnam
08:40 Message from the Organizer Dr. Tran Ngoc Thach
Director, CLRRI, Vietnam
08:50 Congratulation Address TBD
Leader of Can Tho City
08:55 Message from the Sponsor Mr. Bui Van Kip
Bayer Vietnam Ltd.
09:00 Introduction to Keynote Speaker Dr. Jan Leach
Colorado State University, USA
09:05
Keynote Speech: Bacterial Blight of Rice: A
Four Decade of Research and Partnership
for Sustainable Rice Production
Dr. Casiana M. Vera Cruz
IRRI, Philippines
09:35 Special Event: Recognition of Dr Casiana
M. Vera Cruz Contribution to the Bacterial
Blight of Rice Research Community
Dr. Jan Leach
Colorado State University
USA
09:45 Group Photo Session
10:00 Coffee Break
10:15 Introduction to Keynote Speaker Dr. Ricardo Oliva
IRRI, Philippines
10:20 Keynote Speech: Managing Rice Bacterial
Blight in a Changing Climate
Dr. Jan Leach
Colorado State University, USA
Chair: Dr. Nguyen Hong Son, VAAS, Vietnam
10:50 Genotypic and pathotypic diversity of
bacterial blight diseases (Xanthomonas
oryzae pv. oryzae) in the Mekong Delta of
Vietnam
Dr. Nguyen Duc Cuong
Cuu Long Delta Rice Research
Institute, Vietnam
11:15 Monitoring of bacterial blight populations
in the field
Dr. Ricardo Oliva
IRRI, Philippines
11:40 Diversity of bacterial leaf blight diseases
strains (Xanthomonas oryzae pv. oryzae) in
Northern Vietnam
Dr. Tong Van Hai
Vietnam National University of
Agriculture, Vietnam
12:05 The evolutionary ebb and flow of tissue-
specificity and Xanthomonas vascular
pathogenesis
Dr. Jonathan M. Jacobs
Ohio State University, USA
12:05 Luncheon 12:05-13:30
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Chair: Dr Wolf Frommer, Heinrich Heine University, Germany
13:30 Pathogenic and Molecular Diversity of
Xanthomonas oryzae pv. oryzae Population
Affecting Rice Granaries in Malaysia
Mrs. Kogeethavani R
Malaysian Agriculture and
Development Institute, Malaysia
13:55 Evaluation of the resistance of rice
lines/varieties to bacterial leaf blight
(Xanthomonas oryzae pv. oryzae) in the
North of Vietnam
Dr. Nguyen Huy Chung
Plant Protection Research Institute,
Vietnam
14:20 Characterization of the bacterial blight and
bacterial leaf streak resistance locus Xo1 in
Carolina Gold Select rice by Nanopore-
based whole genome sequencing
Dr. Adam J. Bogdanove
Cornell University, USA
14:45 Introgression of Leaf Blight Resistance
Genes into Indica Cultivar BT7 through
Marker-Assisted Backcrossing
Dr. Pham Thien Thanh
Field Crops Research Institute,
Vietnam
15:10 Coffee Break
Chair: Dr. Lin-Woo Kang, Konkuk University, Korea
15:25 Detection and grouping rice cultivars based
on the presence of Xa-genes in Situbondo
and Jember, Indonesia
Dr. Hardian Susilo Addy
University of Jember,
Indonesia
15:50 Overexpression of Antisense MIR396e
Confers Bacterial Blight Resistance through
Interfering Accumulation of miR396e/f-3p
in Rice
Dr. Huamin Chen
Chinese Academy of Agricultural
Sciences, China
16:15 Advances in Bacterial Blight of Rice: R
Genes versus Pathogen Population Structure
in South and South-East Asia
Dr. Jagjeet Singh Lore
Punjab Agricultural University,
India
16:40 Identification of QTLs Associated with
Bacterial Leaf Blight Resistance in
Khangdan18 Cultivar
Dr. Nguyen Quoc Trung
Vietnam National University of
Agriculture, Vietnam
16:45 Poster Presentations 16:45-15:45
18:00 Welcome Reception 18:00-20:30
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Tuesday - August 20, 2019 (Day 2)
Chair: Dr. Adam Bogdanove, Cornell University, USA
08:00 Introduction to Keynote Speaker Dr. Adam Bogdanove
Cornell University, USA
08:05 Keynote Speech: Engineering pathogen
resistance faster than pathogens can evolve
new virulence mechanisms?
Dr Wolf Frommer
Heinrich Heine University,
Germany
08:35
Development of bacterial leaf blight resistant
hybrids for sustainable rice farming
Dr. Deo Mishra
Bayer BioScience, India
09:00 Marker-assisted Breeding for Resistance to
Bacterial Leaf Blight in DT82 Rice Variety
Dr. Vo Thi Minh Tuyen
Agricultural Genetics
Research Institute, Vietnam
09:25
Profiling endophytic microbiome in bacterial
blight diseased leaves of rice identifies
bacterial endophytes with pathogen
antagonism and disease suppression
Dr. Fenghuan Yang
Chinese Academy of Agricultural
Sciences, China
09:50 Phage therapy in controlling rice bacterial leaf
blight caused by Xanthomonas oryzae pv.
oryzae
Dr. Nguyen Thi Thu Nga
Can Tho University,
Vietnam
10:15 Coffee Break 10:15-10:25
Chair: Dr. Ricardo Oliva, IRRI
10:25 Characterization of Bacteriophages Infecting
Xanthomonas oryzae pv. oryzae
Ms. Rejeki Desi
University of Jember, Indonesia
10:50 Biological control of Bacterial Leaf Blight of
Rice by Bacillus strains in the Mekong Delta:
Current status and future prospects
Dr. Tran Vu Phen
Can Tho University, Vietnam
11:15 Eco-friendly Management of Bacterial Leaf
Blight Disease of Rice in Kuttanadu, India
Dr. Reeny Zacharia
Rice Research Station, Kerala
India
11:40 Defense Biochemical Alterations in Rice
Leaves on Induced Resistance against
Xanthomonas oryzae pv. oryzae
Dr. Le Thanh Toan
Can Tho University,
Vietnam
12:05 Xanthomonas oryzae-Triggered Production of
Atypical Rice Small RNAs During
Infection
Dr. Sebastian Cunnac
IRD, France
12:30 Luncheon 12:10-13:30
Chair: Dr Jagjeet Singh Lore, Punjab Agricultural University, India
13:30 The RpoN2-PilRX system regulates type VI
pilus-dependent motility and is required for
virulence in Xanthomonas oryzae pv. oryzae
Dr. Chao Yu
Chinese Academy of Agricultural
Sciences, China
The 6th International Conference on Bacterial Blight of Rice
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13:55 Combined Transcriptome and Proteome
Analysis of the Pathogenicity-activated
Xanthomonas oryzae pv. oryzae
Dr. Lin-Woo Kang
Konkuk University,
Korea
14:20 Xanthomonas oryzae pv. oryzae T3SS-
effector XopF interacts with multiple rice
targets to subvert the immune responses
during bacterial blight development
Dr. Kalyan K. Mondal
Indian Agricultural Research
Institute, India
14:45 Xylose-dependent hrp gene expression in
Xanthomonas oryzae pv. oryzae
Dr. Seiji Tsuge
Kyoto Prefectural University,
Japan
15:10 Bioinformatic approaches to uncover genetic
acquisitions associated with epidemic
populations of Xanthomonas oryzae pv. oryzae
Dr. Alvaro L Perez-Quintero
Colorado State University,
USA
15:35 Coffee Break
Chair: Dr. Jan Leach, Colorado State University, USA
15:50 Quorum sensing and Xanthomonadin
biosynthesis in the phytopathogen
Xanthomonas
Dr. He Ya-Wen
Shanghai Jiao Tong University,
China
16:15
Getting into the weeds: How monitoring
Xanthomonas species outside the paddy can
inform crop management and our
understanding of pathogen evolution
Dr. Jillian Lang
Colorado State University,
USA
16:40 OsERF#123, a new susceptibility gene for
bacterial blight of rice
Dr. Mathilde Hutin
IRD, France
17:05 Legal Framework for Genome Editing
Approaches in Agricultural Development
Dr. Sarah Schmidt
Heinrich Heine University,
Germany
17:30 Wrap-up, Closing Remarks and
Announcement of the 7th ICBB
Dr. Wolf Frommer /
Dr. Tran Ngoc Thach
Wednesday - August 21, 2019 (Day 3)
CLRRI Field Tour
08:00 Bus from Can Tho to CLRRI Headquarter
09:00 Visit CLRRI Research/Experimental Fields
09:45 Visit Variety Demonstration Fields
10:30 Introduction to CLRRI CLRRI Conference Room
The 6th International Conference on Bacterial Blight of Rice
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Keynote Speech Abstracts:
Bacterial Blight of Rice: A Four Decade of Research and Partnership for
Sustainable Rice Production
Vera Cruz CM
International Rice Research Institute, Los Banos, Laguna 4031 Philippines
Effective management of rice diseases is critical to sustaining rice productivity.
Despite knowledge of the disease over a century ago, bacterial blight (BB) of rice
caused by Xanthomonas oryzae pv. oryzae (Xoo) remains a serious threat to rice
production, especially with a warming climate and increasing frequency of extreme
weather events that predispose the disease. The importance of BB was fully
recognized when high yielding varieties lacking resistance were deployed widely in
the late 1960s. As host plant resistance is the most economical and ecological
approach to manage the disease, IRRI scientists have initiated research on variability
of Xoo, beginning in the late 1960s, and studied its population structure across
countries and regions. This work was accomplished through organized partnerships
with national programs in Asia and advanced research institutions in the US and
Europe in the mid-1980s to early 2000s (ARBN), and globally through CGIAR
Programs (GCP) in mid-2000s. Rice genetic resources, such as rice differentials,
resistance sources, near-isogenic lines (NILs), and pyramids in elite backgrounds were
developed in collaborations between Japanese and IRRI breeders using well-
characterized physiological Xoo races and strains. Advances in molecular genetics
and genomics-enabled approaches provided powerful insights into Xoo biology and
evolution as well as disease epidemiology and deployment strategies for resistance
sources. These studies revealed the contributions of avirulence/virulence genes to Xoo,
fitness in the field, and their utility in prediction of Xa-gene durability. In the late
1990’s, molecular markers for mapped R-genes were developed; these were refined
with advances in sequencing, genomics and analytical approaches, and cloning of R-
genes. The various platforms developed from these have been refined, shared, and
applied in international and national breeding programs, including private
organizations. These organized partnerships continue in breeding networks in Asia
and Africa. Productive collaborations with breeders have resulted in the release of
better combinations of Xa genes in popular varieties and elite backgrounds, and
effective combinations of Xa genes with other disease R genes and abiotic stress
tolerance genes/QTL. With precise diagnostic SNP markers for both rice and Xoo,
resistances are strategically deployed more efficiently and effectively in real-time at a
global scale.
On the pathogen side in the mid-2000s, the availability of published Xanthomonas
genome sequences led to exciting discoveries of transcription activator-like (TAL)
effectors in Xoo, and the corresponding susceptibility targets, SWEET sucrose
transporters, in rice. Modification of the SWEET genes through genome editing
technologies is being used to enhance resistance in a highly precise and targeted way
and will be reported in this conference by partners in the US and Europe.
The 6th International Conference on Bacterial Blight of Rice
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Finally, enriching our partnerships will continue to address the challenges in
sustaining a healthy rice production environment. Pursuing our goal, the 6th ICBB
provides an excellent opportunity to share progress and identify research areas for Xoo
and BB as a focus for the next 10-20 years.
Keywords: Xanthomonas oryzae pv. oryzae races, fitness, near-isogenic lines, gene
pyramids
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Managing Rice Bacterial Blight in a Changing Climate
Jan E. Leach, Stephen Cohen and Jennifer Shipp
Colorado State University, Fort Collins, CO, USA
Phenotypic responses of plants to biotic and abiotic stresses are frequently studied as
the outcome of interactions between plants and one or two species of microbes or a
single abiotic stress. However, in the phytobiome, plant health and productivity are
impacted by simultaneous interactions among multiple organisms and the
environment, and frequently, the responses to these interactions are distinct and would
not be predicted from studying less complex systems. Many plant diseases are
predicted to intensify as environmental temperatures increase, and, to compound the
problem, many widely used sources of disease resistance fail to control disease at high
temperatures. The molecular mechanisms for how plants respond to simultaneous
heat- and pathogen-imposed stresses, however, are not known. From a meta-analysis
of publicly available rice stress response transcriptome data, we demonstrated that rice
generally up-regulates hormone-responsive genes during stress responses, most
notably genes in the abscisic acid (ABA) pathway. This is consistent with our findings
on the impacts of high temperature on bacterial blight (BB) disease and resistance.
Heat stress increases susceptibility of rice to Xanthomonas oryzae pv. oryzae (Xoo),
and most BB resistance genes are not effective at high temperatures. Of seven BB
resistance genes tested so far, only one, Xa7, is more effective at elevated
temperatures. A transcriptomics experiment involving rice plants infected with Xoo
during high temperature stress revealed an upregulation of ABA pathway genes,
consistent with higher levels of disease. In plants expressing Xa7-based resistance at
high temperature, however, the ABA pathway genes were downregulated. This trend
suggests that during simultaneous heat and disease stresses, plants undergoing an Xa7-
based resistance prioritize response to pathogen over the response to abiotic stress.
Ongoing research is focused on understanding how these pathways contribute to
increased plant disease at high temperature, the impact of other abiotic stresses on
disease and resistance, and how we can translate this information to develop more
effective control of bacterial diseases in the face of a changing climate.
Keywords: biotic stress, abiotic stress, climate, ABA, phytobiome
The 6th International Conference on Bacterial Blight of Rice
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Engineering Pathogen Resistance Faster Than Pathogens Can Evolve New
Virulence Mechanisms?
Joon Seob Eom1, Ricardo Oliva3, Frank F White4, Bing Yang5 and Wolf B Frommer12
1Institute for Molecular Physiology, Heinrich Heine Universität Düsseldorf and Max
Planck Institute for Plant Breeding Research, Köln, Germany 2Department of Plant Biology, Carnegie Science, Stanford, CA 94305, USA 3International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines 4Department of Plant Pathology, University of Florida, 32611, USA 5Division of Plant Sciences, University of Missouri – Columbia, MO65211, USA
At present, we only partially understand how assimilates are translocated from leaves
into seeds. We identified a new class of transporters for cellular uptake and efflux of
sugars (SUTs and the SWEETs). They were identified in Arabidopsis and we
analyzed their roles in the physiology of both Arabidopsis and crop plants. We found
that three SWEET13 paralogs play critical roles in phloem loading in maize and
identified SWEET4c as a hexose transporter in the basal endosperm transfer cell layer
of maize kernels. We identified SWEET11 and 15 as key transporters during seed
filling in rice. We try to establish the complete path of sugars from the site of
synthesis to the ultimate storage site. We develop fluorescent biosensors for sugars
and transporter activity and are exploring the regulation of the transport processes.
Surprisingly, we found that SWEETs function as pathogen susceptibility factors.
Xanthomonas oryzae pv oryzae (Xoo), the causative agent of leaf blight in rice, uses
TAL effectors to ectopically induce the expression of specific sets of SWEET genes.
If SWEET gene induction is blocked, e.g. by genome editing of effector binding sites,
the resulting plants are resistant. We engineered a large number of R gene variants
that can be deployed in intelligent manner possibly at a pace relative to the spread of a
pathogen that created a new TAL effector for inducing alternative SWEETs. We have
implemented these R gene variants in elite rice varieties and intend to provide them to
breeders for dissemination, in particular to subsistence farmers. To be able to deploy
the best possible R gene combination, we also developed a diagnostic kit that allows
rapid testing of new Xoo isolates. The simplest hypothesis is that SWEETs serve in
pathogen nutrition, we can however not exclude that the consequence of SWEET
induction is priming of defense pathways. We have begun now exploring the SWEET-
related disease mechanism.
Keywords: effector, sugar transporter, R gene, SWEET
The 6th International Conference on Bacterial Blight of Rice
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Oral Presentations’ Abstracts
Session I: Current Assessment of Bacterial Blight Disease
Genotyic and Pathotypic Diversity of Xanthomonas oryzae pv. oryzae
Causing Rice Bacterial Leaf Blight in the Mekong Delta of Vietnam
Nguyen Thi Phong Lan, Tran Thi Nam Ly, Tran Ha Anh, Nguyen Thi Xuan Mai, Tran
Phuoc Loc, Vo Thi Thu Ngan, Tran Thi Kieu, Vo Thi Da Thao, Nguyen Duc Cuong
Plant Protection Department, Cuu Long Delta Rice Research Institute, Vietnam
Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a
major rice disease which reduces grain quality and yield of rice. Bactericides, culture
practices and resistant varieties have been developed for BLB management. Among
control measures, planting resistance varieties has been considered as the most
effective, sustainable and ecofriendly approach. Development of good resistance
varieties depends on knowledge of BLB resistance gene and pathotypes diversity of
Xoo population. The virulent study was conducted on 12 near-isogenic lines (IRBB1,
IBB2, IRBB3, IRBB4, IRBB5, IRBB7, IRBB8, IRBB10, IRBB11, IRBB13, IRBB14,
IRBB21), each harboring a single resistance gene together with IR24 and Xoo strains
collected from 8 provinces in the Mekong delta of Vietnam from 2017 - 2018. All
strains of Xoo were virulent to the resistance genes (Xa1, Xa2, Xa10, Xa11, Xa13), in
contract Xa5 was effective against almost strains of Xoo population. Total 13
pathotypes were identified regarding reaction between Xoo strains and the differential
lines. Among these, P10 was highly virulent which showed susceptible to all single
BLB resistance genes. In addition, P9 was found as the most popular pathotype and
was distributed throughout 6 provinces in the region. For genetic characterization, 34
strains of Xoo were analyzed by polymerase chain reaction (PCR) using two PCR-
based assays. A high level of genetic polymorphism was found and the strains were
grouped into 2 clusters. Evaluation of 30 widely grown and promising rice varieties
(original from Vietnam and IRRI) for its reaction against Xoo strains belonging to
different pathotypes was conducted under greenhouse conditions. All of Vietnamese
and IRRI improved varieties were susceptible to the pathotypes that were inoculated.
This study indicated that, there was no correlation between pathotypes and genetic
clusters because each genetic cluster involves Xoo strains regarding different
pathotypes. Single resistance gene could not give broad-spectrum resistance against
Xoo population in the Mekong delta, except Xa5 is widely effective.
Keywords: bacterial leaf blight of rice, near isogenic line(s), resistance gene,
pathotype
The 6th International Conference on Bacterial Blight of Rice
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Monitoring of Bacterial Blight Populations in the Field
Ricardo Oliva
Rice Breeding Platform, International Rice Research Institute
The emergence of highly aggressive clones of plant pathogens in agricultural
ecosystems represents an important threat to food security. Bacterial blight, caused by
Xanthomonas oryzae pv. oryzae (Xoo), is the most important bacterial disease of rice
in Asia. The pathogen appears to evolve a number of populations showing distinctive
patterns of interaction with rice resistance gene (Xa). In that scenario, knowledge on
the distribution of populations may be critical to predict seasonal disease outcomes
and reduce the risk of yield loss. Using genomic and phenotypic information on a
large set of Xoo strains, we developed stable molecular markers that can distinguish
pathogen populations. Moreover, the markers appear to be highly sensitive in a wide
range of samples, from DNA to infected-leaf samples. Using field experiments, we
demonstrated that real-time surveillance of Xoo populations is possible during the
cropping season. More importantly, the markers have been transferred to a
commercial platform, allowing other users to benefit from this technology. We expect
in the near future that high-throughput and rapid monitoring of rice-growing areas in
Asia will drive deployment and genetic improvement effort in the region.
Keywords: disease outbreaks, host plant resistance, surveillance, race-specificity
The 6th International Conference on Bacterial Blight of Rice
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Diversity of Xanthomonas oryzae pv. oryzae Strains Causing Bacterial
Blight of Rice in Northern Vietnam
Hai Tong Van, Trung Nguyen Quoc, Chau Nguyen Thi Cam, Hien Phan Thi and
Hanh Nguyen Thi Thuy
Faculty of Biotechnology, Vietnam National University of Agriculture, Ha Noi,
Vietnam
Bacterial leaf blight disease caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of
the most severe diseases in rice – cultivating areas of Vietnam. Recently, it not only
caused damage season crop but also in spring season and resulted in great loss of yield
and quality. To prevent this disease, the use of resistance varieties offers the most
economical efficiency. In order to breed resistant varieties, it is necessary to study on
diversity of Xoo strains, as well as the distribution of each strain and identify to
resistance genes for each strain.
In this study, we conducted the collection, isolation and identification of bacterial leaf
blight diseases strains through reaction with near isogenic lines and comparing the
diversity of current strains with 2012 strains. Seventy-two disease samples were
collected on 29 rice varieties in 15 provinces in North Vietnam. In these samples, 146
isolates were screened and isolated by XORF & XOR marker. Seven strains were
identified by inoculation in near isogenic lines are 2A, 3A, 4, 5A, 7, 11 and 12 strain.
2A, 3A and 5A strain were most common. Strain 12 had highest pathogenicity. Xa5
and Xa7 gene were the most resistant genes. The distribution of Xoo strains was
mapped. Comparing the current strains with the strains of 2002 found that the strains
composition was less, but strains 5A was more widely distributed.
Keywords: bacterial leaf blight, isogenic, isolate, Xanthomonas oryzae pv. oryzae,
inoculation, resistance genes.
The 6th International Conference on Bacterial Blight of Rice
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Session II: Epidemiology and Population Biology of Bacterial Blight
The Evolutionary Ebb and Flow of Tissue-Specificity and Xanthomonas
Vascular Pathogenesis
Jonathan M. Jacobs
Department of Plant Pathology and Infectious Disease Institute, Ohio State University,
Columbus, OH, USA
Plant pathogenic Xanthomonas bacteria cause vascular and non-vascular diseases of
over 200 plant species. The factors that contribute to Xanthomonas evolution for
niche-specific, vascular or non-vascular behavior remain unclear. We examined the
molecular and evolutionary basis for vascular pathogenicity in Xanthomonas species.
We found a single gene cbsA, which distinguishes vascular from non-vascular Gram-
negative plant pathogens. Among all sequenced plant-associated microbes, cbsA,
which encodes a cellobiosidase, was conserved in vascular pathogens from three
distinct genera: Xanthomonas, Xylella, and Ralstonia. Heterologous expression of
cbsA in non-vascular Xanthomonas species resulted in pathotype conversion allowing
for xylem colonization, while its deletion in vascular species resulted in the loss of
xylem colonization, demonstrating that cellobiosidase activity is both sufficient and
necessary for vascular colonization. Notably heterologous expression of CbsA
permitted pathotype conversion, enabling apoplast barley and rice Xanthomonas
pathogens to cause xylem, blight pathogenesis. We inferred several instances of
concomitant gain and loss of cbsA and vascular pathogenicity in Xanthomonas, where
cbsA was acquired through horizontal gene transfer in what are now vascular lineages,
and alternatively lost through transposon mediated insertion in non-vascular lineages.
The dynamic evolution of cbsA suggests that rather than representing evolutionary
endpoints, vascular and non-vascular modes of infection exist on a continuum, and
populations easily flow from one end to another depending on the selective
environment.
Keywords: evolution, vascular, xylem, pathogen, Xanthomonas
The 6th International Conference on Bacterial Blight of Rice
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Molecular Identification and Characterization of Xanthomonas oryzae pv.
oryzae Isolated from Different Rice Growing Areas of Pakistan
Sumera Yasmin1, Ali Faiq1, Khansa Ejaz1, M. Asif1, M. Asif1, M. Hanna Nguyen2,
C.M. Vera Cruz2, Ricardo Oliva2 and M. Arif1
1National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad,
Pakistan 2 International Rice Research Institute (IRRI) Los Banos, Philippines
Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of
the major threats to rice as it reduces yield and grain quality in all rice growing areas.
The study has been conducted for molecular characterization and screening of
Pakistani strains of Xoo against different varieties of rice. Molecular detection of the
pathogen was carried out using species and pathovar specific primers. LAMP was
used to study genetic relatedness of newly isolated Xoo strains. Different isolates of
the pathogen were confirmed in vivo by pathogenicity tests using clip inoculation
method under net house conditions. Screening of different Xoo isolates against
different varieties of rice was carried out to determine the most effective R gene or
combination of R genes against Xoo and to identify the most virulent strain. The
present study provided significant information to find the best combination of R genes
to develop BLB resistant rice varieties.
Keywords: pathogen, strain, R genes, Xanthomonas oryzae
The 6th International Conference on Bacterial Blight of Rice
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Pathogenic and Molecular Diversity of Xanthomonas oryzae pv. oryzae
Population Affecting Rice Granaries in Malaysia
Kogeethavani R1, Suzianti I.V1, Fatin Nurliyana A1, Nurshamiza M.Y1
1Rice and Paddy Research Centre, Malaysian Agriculture and Development Institute,
Selangor 43400, Malaysia
The bacterial blight disease (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is
one of the major diseases of economically importance in Malaysian rice production. It
became increasingly evident in recent years due to its severe outbreaks in 2013 -2017
in most rice growing states in the country. No local varieties were found resistance to
this disease. Breeding for resistance is the most practical and cost-effective approach
for sustainable management. The purpose of this study is to obtain information on the
pathogenic and haplotypic variability of Xoo to develop an effective breeding strategy
for BB resistance. Among forty-two isolates assessed for their interactions with 10
near-isogenic rice lines (NILs) with known single resistance genes (Xa genes), 16
pathotypes (Pxo-1 to Pxo-16) were identified. Pathotype Pxo-1 showed incompatible
interaction with all the Xa genes and was the predominant with highest pathotype
frequency (21%). Pathotypes Pxo-14, Pxo-15, and Pxo-11 also considered as a major,
containing pathotype frequency between 11-14%. In rest of designated pathotypes,
Xoo isolates had incompatible interaction with one or more Xa genes except for Xa5
gene which had incompatible interaction to all the Xoo isolates. Conferring resistance
against 100% of the isolates, Xa5 emerged as the most effective gene, followed by
Xa7 (92 %), Xa14 (76 %) and Xa21 (69 %). Thirty haplotypes were detected among
the Xoo population at 58% similarity using rep-PCR fingerprinting. However, a weak
correlation was observed between the pathotypes and these haplotypes. This suggests
a high degree of DNA polymorphism among strains within many pathotypes. Lowest
disease severity and virulence frequency were observed on NILs carrying Xa5, Xa7,
Xa14 and Xa21 genes indicating their potential use as donor parent in a breeding
program. Incorporation of these four genes appears to be the most suitable Xa gene
combination to be deployed in Malaysian rice cultivars.
Keywords: pathotypes, haplotype, Xa gene effectiveness, Xanthomonas oryzae, near
isogenic lines
The 6th International Conference on Bacterial Blight of Rice
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Session III: Host Resistance: Genetics and Molecular Biology
Evaluation of the Resistance of Rice Lines/Varieties to bacterial leaf blight
(Xanthomonas oryzae pv. oryzae) in the North of Viet Nam
Nguyen Huy Chung, Nguyen Tien Hung, Nguyen Thi Tho, Le Thi Phuong Lan,
Lam Thi Nhung
Plant Protection Research Institute, Hanoi, Vietnam
Bacterial leaf blight (Xanthomonas oryzae pv. oryzae), is a major disease of rice in the
tropics and subtropics of Asia countries (Mew.1987). Bacterial leaf blight can cause
severe yield loss of up to 50% - 70% in severely infected fields (Mew.1987). In Viet
Nam, Bacterial leaf blight (BLB) is one of the destructive diseases and occurs year-
round depending on the regions. In the North, the disease usually appears in the
summer crop season. However, it occurs more and more often and can cause serious
damage in the winter-spring crop season. The effectiveness of control BLB is limited.
Thus, utilizing resistant varieties is a good strategy for disease management. Study on
population diversity of pathogen, varieties tolerance/ resistance has been focused in
many countries (Maryam, et al.2012, Lu, et al.2014, Liu et.al.2017). This research will
focus on the evaluation the resistance of near isogenic lines (NIL) to BLB and
screening the resistance of rice varieties to BLB in the North of Viet Nam.
Twenty-eight NIL lines conferring one or more resistant genes were inoculated with
twenty-eight isolates of X. oryzae pv. oryzae collected from 15 provinces using
clipping inoculation method. One hundred and fifty traditional rice varieties and forty-
four popular cultivated varieties were also screened for BLB resistance. Scores were
recorded following the Standard Evaluation System for Rice (IRRRI, 2014).
The result shows that among NIL lines, IRBB4, IRBB5, IRBB21 were the lines with a
single gene (Xa4, xa5, Xa21 respectively) more resistant to BLB. These lines were
resistant/medium resistant to 54-87% isolate inoculated. In addition, NIL lines
conferring multiple genes revealed more resistant to BLB than the single gene NIL.
Ten lines were resistant to more than 50% isolate inoculated, in which IRBB53
(xa5/xa13), IRBB50 (Xa4/xa5), IRBB54 (xa5/Xa21) were resistant to 85%, 66% and
64% isolate of BLB pathogen in this study. In the traditional varieties group, there
were 18 resistant varieties (score 3), 64 medium resistant varieties (Score 5), and 24
susceptible varieties (Score 7-9) account for 12 %, 64% and 24% of the total
respectively. There was a high percentage (62%) of susceptible varieties within
popular varieties, whereas 18 % resistant, and 20% medium resistant varieties
recorded.
This study indicates that resistant genes Xa4, xa5, Xa21 and resistant traditional
varieties can be used for breeding for BLB resistance in the North of Viet Nam and
more research on pathotype of BLB need to be conducted.
Keywords: Bacterial leaf blight, Xanthomonas oryzae pv. oryzae, NIL, resistant gene.
The 6th International Conference on Bacterial Blight of Rice
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Characterization of the Bacterial Blight and Bacterial Leaf Streak
Resistance Locus Xo1 in Carolina Gold Select Rice by Nanopore-based
Whole Genome Sequencing
Andrew C. Read1, Matthew J. Moscou2, Aleksey V. Zimin3, Geo Pertea3, Rachel S.
Meyer4†, Michael D. Purugganan4,5, Jan E. Leach6, Lindsay R. Triplett6††, Steven L.
Salzberg3,7, and Adam J. Bogdanove1*
1Plant Pathology and Plant Microbe Biology Section, School of Integrative Plant
Science, Cornell University, Ithaca, NY USA 2The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH UK 3Center for Computational Biology, McKusick-Nathans Institute of Genetic Medicine,
Johns Hopkins School of Medicine, Baltimore, MD, USA 4Center for Genomics and Systems Biology, New York University, New York, NY USA 5Center for Genomics and Biology, New York University Abu Dhabi, Saadiyat Island,
Abu Dhabi, United Arab Emirates 6 Department of Bioagricultural Sciences and Pest Management, Colorado State
University, Fort Collins, CO USA 7 Departments of Biomedical Engineering, Computer Science, and Biostatistics, Johns
Hopkins University, Baltimore, MD USA
We recently mapped the Xo1 locus for resistance to bacterial blight and bacterial leaf
streak, found in the American heirloom rice variety Carolina Gold Select, to a region
that in the Nipponbare reference genome is rich in NLR genes. NLR genes are often
clustered, evolving via duplication, contraction, and transposition. This complexity
makes NLR gene-rich regions of a genome challenging to assemble by short-read
sequencing. Sequence capture by hybridization approaches, such as RenSeq, have
been used to catalog NLR genes in several plant species, but these can miss structural
variants and do not reveal genomic location or arrangement. Toward the identification
of the Xo1 gene, we combined long (Nanopore) and short (Illumina) reads to generate
a high-quality genome assembly for Carolina Gold Select. We identified 529 full or
partial NLR genes and discovered, relative to the reference, an expansion of NLR
genes at the Xo1 locus. One NLR gene at Xo1 has high sequence similarity to the
cloned, functionally similar Xa1 gene. Both harbor an integrated zfBED domain and
near-identical, tandem, C-terminal repeats. Across diverse Oryzeae, we identified two
sub-clades of such NLR genes, varying in the presence of the zfBED domain and the
number of repeats. In addition to the Xo1 candidate, the genome sequence also
revealed the blast resistance gene Pi63 at the Xo1 locus. Our results show that genome
sequencing combining Nanopore and Illumina reads effectively resolves NLR gene
loci, providing context as well as the content. Our identification of an Xo1 candidate is
an important step toward mechanistic characterization, including the role(s) of the
zfBED domain. And, the Carolina Gold Select genome assembly will facilitate
identification and exploitation of other useful traits in this historically important rice
variety.
Keywords: genome sequencing, NLR gene, Xo1 locus, zfBED domain
The 6th International Conference on Bacterial Blight of Rice
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Introgression of Bacterial Leaf Blight Resistance Genes into Indica
Cultivar BT7 through Marker-Assisted Backcrossing
Pham Thien Thanh, Nguyen Tri Hoan, Tang Thi Diep, Phan Thi Thanh
Field Crops Research Institute, Vietnam
Rice bacterial leaf blight disease caused by Xanthomonas oryzae pv. oryzae (Xoo) is
the most serious threat to rice production in the North of Vietnam. An Indica cultivar,
BT7, is a popular rice variety with farmers of Northern Vietnam because of its good
eating quality. However, the variety is highly susceptible to bacterial blight disease.
The development of resistant cultivar has been the most effective and economical
strategy to control the disease. Three resistance genes (xa5, Xa7, Xa21) considered to
be resistance to virulent bacterial strains from Northern Vietnam were transferred
from near-isogenic line, IRBB66, using a marker-assisted backcrossing breeding
strategy, into the BT7. An advance backcross line, BT7KBL-03, of BC5F4 generation
was evaluated after inoculation with two isolates of the pathogen from the Northern
Vietnam. The combination of three genes in BT7KBL-03 line provided a wider
spectrum of resistance to the pathogen population prevalent in the region. The
morphological, yield, grain quality, and yield-contributing characteristics of
BT7KBL-03 were significantly similar to those of BT7 cultivar. The newly developed
leaf blight resistant improved line will contribute to widening cultivation area of the
highly adoptable BT7 by farmers.
Keywords: Rice, bacterial blight gene pyramiding, marker-assisted backcrossing
The 6th International Conference on Bacterial Blight of Rice
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Detection and Grouping Rice Cultivars Based on the Presence of Xa-genes
in Situbondo and Jember, Indonesia
Addy, HS1,2,3*, Rasmiyana1,2, Narulita, E1,2
1Post-Graduate Program, Study Program of Magister Biotechnology. University of
Jember, Jember, Jawa Timur 68121, Indonesia. 2Division of Biology Molecule and Biotechnology, Center for Development of
Advanced Sciences and Technology, University of Jember 3Study Program of Plant Protection, Faculty of Agriculture, University of Jember
A destructive pathogen that significantly affects rice production is Xanthomonas
oryzae pv. oryzae, causing bacterial leaf blight. The use of resistant variety is the most
effective and economic technique to reduce the impact of the disease. This study aims
to analyze the genetic status of rice (Oryza sativa) related to their resistance to X.
oryzae pv. oryzae. The disease and severity of bacterial leaf blight were assessed in
the field through a diagonal random sampling method. Detection of rice resistant
genes was done by polymerase chain reaction (PCR) with eight Xa specific primers.
Its molecular trait and environmental condition were statistically analyzed to
determine the correlation between the average temperature and rain intensity against
disease incidence and disease severity. The average value of disease incidence and
severity in the generative stage were higher than in the vegetative stage. About four
groups of rice were grouped based on the presence of Xa genes sequences, mostly
Xa10 and Xa13, including a cultivar with five Xa genes. There was a weak correlation
between the presence of resistance genes with disease incidence and severity of
bacterial leaf blight. Environmental factors showed a weak correlation with disease
incidence or disease severity. Rice varieties cultivated in the regency of Jember and
Situbondo carry mostly Xa10 and Xa13 resistance genes, with a less significant role
on disease severity.
Keywords: Bacterial leaf blight, Xa genes, Xanthomonas oryzae, PCR detection, Xa
specific primers
The 6th International Conference on Bacterial Blight of Rice
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Overexpression of Antisense MIR396e Confers Bacterial Blight Resistance
through Interfering Accumulation of miR396e/f-3p in Rice
Hu JX, Zhu XM, Cao YQ, Chen YT, Yu C, Yang FH, Chen HM, He CY
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant
Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
miRNAs, a class of 20- to 24-nucleotide-long endogenous regulatory RNAs, are
involved in the response to environmental stresses including biotic and abiotic stresses.
miRNAs inhibitors are extensively used for curing certain miRNA-mediated diseases
based on the introduction of an antisense oligonucleotide in the animal. However,
antisense miRNAs research was hardly reported in plant miRNAs. miR396 family is
very conserved in more than 50 plant species including rice. The biological functions
of miR396 in growth, development, and responses to pathogen attacks and abiotic
stress through controlling the transcription of the target GRFs (growth-regulating
factors, GRFs). Our previous work showed that miR396e/f -3p were downregulated
by bacterial infection by Xanthomonas oryzae pv. oryzae. To further elucidate the
biological functions of miR396e/f-3p, antisense MIR396e driven by 35S promoter for
constitutive expression was transformed into the rice. The transgenic rice plants
showed significant bacterial blight resistance. Further work showed that the
accumulation of mature miR396e/f-3p but not miR396e-5p was decreased
significantly in transgenic plants compared with that in wildtype. The predicted
miR396f-3p target EXO70 (exocyst complex subunit family protein) and miR396e-3p
target EH (hydrolase, alpha/beta fold family domain-containing protein) were
upregulated in antisense MIR396e transgenic plants. Transient expression assay
showed that overexpression of either EXO70 or EH in rice protoplast, induced the
transcript of defense genes such as PR1a, PR1b, PR5, and WRKY45. Therefore, these
results demonstrate that miR396e/f-3p play key regulatory roles in the response to
bacterial infection. In addition, the current study provides an example for the
application of antisense nucleotide in functional analysis of miRNAs in rice.
Keywords: miR396e; antisense MIR396e; bacterial blight of rice
The 6th International Conference on Bacterial Blight of Rice
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Advances in Bacterial Blight of Rice: R Genes versus Pathogen Population
Structure in South and South-East Asia
J.S. Lore1, J. Jain1, M. S. Hunjan1, R. Kaur1, G. S. Mangat1, G. S. Laha2, N. W. Zaidi3,
O. Ricardo3, C. M. Vera Cruz3
1Punjab Agricultural University, Ludhiana, India,2Indian Institute of Rice Research,
Hyderabad, India,3International Rice Research Institute, DAPO Box 7777, Metro,
Manila, Philippines
Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae [(Ishiyama),
Swing et al.1990], (Xoo) is one of the most widely distributed diseases in different
parts of Asia. BB outbreak can cause up to 50% losses depending on crop stage,
weather, location and the cultivars. The pathogen is highly variable and possesses a
number of virulence factors responsible for its pathogenicity and race differentiation.
A number of Xoo races have been identified based on near-isogenic lines in South and
South-East Asia. The majority of Xoo strains from South Asia became virulent to xa5
while the strains from South-East Asian countries like Korea, Indonesia, Philippines,
Thailand, Malaysia, and Taiwan became avirulent to this gene. Earlier, BB resistance
gene Xa21 showed moderate to a high level of resistance in most of the Asian
countries however, the gene has also been broken down by the new virulent races of
the pathogen. Till date 43 Xa/xa genes for resistance to bacterial blight have been
identified. Some of the new R genes, such as Xa23, Xa33, and Xa38 show broad-
spectrum resistance to BB in India and China. The infection of individual plants by
pathogenic organisms is governed by complex interactions between the host and
pathogen. The pathogen injects transcription activator-like effectors (TALEs) that
bind and activate host susceptibility (S) genes important for the disease. The contrast
phenotypic virulence interaction between Xoo strains and recessive R genes (xa5 and
xa13) has been reported. The pyramided lines carrying xa5+xa13+Xa21 showed
broad-spectrum resistance to the majority of the Xoo strains in South and South-East
Asia. This gene combination has been predominantly deployed in high yielding rice
cultivars. This study can explore the knowledge about the current scenario of
pathogen population structure, phenotypic virulence interaction between host and
pathogen, the effectiveness of new R genes and pyramiding of R genes in South and
South-East Asian countries for the development of high yielding rice cultivars with
durable resistance to bacterial blight.
Keywords: Bacterial blight, R gene, race, Xanthomonas oryzae pv. oryzae
The 6th International Conference on Bacterial Blight of Rice
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Identification of QTLs Associated with Bacterial Leaf Blight Resistance in
Khangdan18 Cultivar
Trung Nguyen Quoc, Hai Tong Van, Chau Nguyen Thi Cam, Hien Phan Thi
Faculty of Biotechnology, Vietnam National University of Agriculture
Bacterial leaf blight (BLB) is one of the most destructive diseases in rice, especially in
a tropical country like Vietnam. Khangdan18 (KD18) is popularly grown cultivar with
the nationwide adaptation, high yield, and stable BLB resistance. In this study, the F2
population of 93 individuals from a cross between KD18 and IR24 variety was used to
identify QTLs associated with BLB resistance. Artificial inoculation method was used
with newly isolated Xanthomonas oryzae pv. oryzae X14.7. Eighty polymorphic SSR
markers distributed on 12 chromosomes were developed by using 2004 DNA markers
to survey parental genomes. Result of QTL analysis based on Composite Interval
Mapping approach with the logarithm of odds score (LOD > 3.0) showed 3 QTLs
associated with BLB resistance: qBLB1, qBLB2, and qBLB7 located on chromosome 1,
2 and 7 respectively. Applying marker-assisted selection, 18 recombinant inbred lines
were developed for further mapping and identifying potential novel BLB resistant
QTLs.
Keywords: QTL analysis, bacterial leaf blight, resistance gene, SSR marker.
.
The 6th International Conference on Bacterial Blight of Rice
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Session IV: Disease Management and Breeding
Development of Bacterial Leaf Blight Resistant Hybrids for Sustainable
Rice Farming
Deo Mishra and Yog Raj
Bayer BioScience, Plot No. 13, Software Layout, Madhapur, Hyderabad-500081,
India
Rice farming community faces a lot of challenges during crop cultivation including
many biotic and abiotic stresses that cause huge economic loss annually. Among them,
bacterial leaf blight (BLB) is a serious devastating biotic stress accounting ~5%
annual loss of rice production. For this disease, an effective and long-lasting solution
has been a challenge. With the aim of having in-built protection in the crop against
BLB, we bred and developed rice hybrids by incorporating native genes for strong
resistance to protect crop yield in a sustainable way. We characterized BLB pathogen
(Xanthomonas oryzae pv. oryzae), screened rice germplasm and improvised the
breeding methodologies. This helped in understanding of pathogen population
structure and deploy effective genetics for broad-spectrum resistance suitable for
affected geographies. Developed products have been vigorously tested and
commercially launched in Asia and are providing big relief from BLB damage to rice
farming community.
Keywords: bacterial leaf blight, pathogen diversity, resistance breeding, gene
pyramiding
The 6th International Conference on Bacterial Blight of Rice
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Marker-assisted Breeding for Resistance to Bacterial Leaf Blight in DT82 Rice
Variety
Vo Thi Minh Tuyen, Nguyen Thi Minh Nguyet, Pham Xuan Hoi
Agricultural Genetics Research Institute, Hanoi, Vietnam
Bacterial leaf blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of
the most destructive diseases in rice (Oryza sativa L.). The introgression of efficiently
resistance genes into high-quality rice varieties will be useful for enhancing the ability
of the durable resistance to BB disease. In this study, Marker-assisted breeding and
artificial inoculation were used to select bacterial leaf blight resistance rice lines. The
result indicated that the promising DT82 variety carried 3 BB resistance genes (Xa4,
Xa7 and Xa21) and showed high resistance to the Xoo races in the field. The new rice
variety had short growth duration (105-110 day in summer season), high quality, easy
cultivation and higher yield than the origin cultivar (Bacthom 7). DT82 variety was
approved by MARD as a potential rice variety, producing on a large scale in the
northern provinces from 2019.
Keywords: bacterial leaf blight, marker-assisted breeding, resistance gene,
Xanthomonas oryzea pv. Oryzea.
The 6th International Conference on Bacterial Blight of Rice
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Profiling Endophytic Microbiome in Bacterial Blight Diseased Leaves of
Rice Identifies Bacterial Endophytes with Pathogen Antagonism and
Disease Suppression
Yang FH,1 Zhang J,1 Zhang HY,2 Ji GH,3 Zeng LX4, Chen W,2 He CY1
1State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of
Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; 2Ottawa Research & Development Centre, Agriculture and Agri-Food Canada,
Ottawa, Ontario, Canada; 3College of Plant Protection, Yunnan Agricultural University, Kunming 650201,
China; 4Plant Protection Research Institute, Guangdong Academy of Agricultural
Sciences, Guangzhou 510640, China
The endophytic microbiome plays an important role in plant health and pathogenesis;
however, little is known about its relationship with bacterial blight (BB) disease of
rice caused by Xanthomonas oryzae pv. oryzae (Xoo). The current study characterized
the compositional structure of microbial endophytic communities in the naturally
occurred BB leaves of rice, collected from Yunnan and Guangdong provinces, China,
through metabarcoding the fungal internal transcribed spacer (ITS) and bacterial 16S
rRNA gene V4 regions. Overall, Ascomycota and Basidiomycota spp. Dominated the
endophytic fungal community, while Basidiomycota spp. Were significantly less
abundant in BB leaves. At the genus level, Khuskia, Pseudopithomyces,
Leptosphaerulina, Trichoglossum, Aureobasidium, Epicoccum, Myrothecium, and
Paraphaeosphaeria were enriched in BB diseased leaves of rice. The endophytic
bacterial community of diseased leaves was significantly enriched with
Gammaproteobacteria spp., Enterobacteriaceae spp., Pantoea spp. And
Pseudomonas spp. (belonging to Proteobacteria), and Curtobacterium spp.
(belonging to Actinobacteria) relative to that in healthy leaves. Among 30 bacterial
strains of endophytes isolated from the diseased leaves, nine Pantoea strains showed
significant inhibition of Xoo. Rice leaves co-inoculated with Xoo and selected
Pantoea strains led to significantly short lesion lengths compared to those inoculated
with Xoo only, suggesting BB suppression by these Pantoea strains. Furthermore,
three Pantoea isolates showed activities in indoleacetic acid (IAA) synthesis, nitrogen
fixation, and active ACC deaminase production, indicating potential plant growth
promotion-related effects. In summary, our study revealed the community structure of
endophytic microbiome in the BB leaves of rice and characterized an array of
endophytic bacterial strains active in Xoo antagonism, BB disease suppression, and
plant growth promotion.
Keywords: bacterial blight of rice, endophyte, microbiome, Pantoea species,
biocontrol
The 6th International Conference on Bacterial Blight of Rice
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Checkmating the Rice Bacterial Blight -PAU Success Story
G S Mangat, Rupinder Kaur, Jagjeet Singh Lore and Renu Khanna
Department of Plant Breeding and Genetics, Punjab Agricultural University,
Ludhiana-141004, Punjab, India
Rice is the staple food for majority of people in the world. Asia accounts for 90% of world’s
rice production. Among India’s different rice-producing states, the highest average rice
yields are obtained in Punjab. Rice was cultivated on around 3.0 million ha in Punjab, with
total paddy production of 19.9 million tons and productivity above 6.5 t/ha during Kharif
2017.
Ongoing climate change is posing a major challenge for sustainable rice production in India.
Though rice production is threatened by a number of biotic stresses, but bacterial blight
(BB) caused by Xanthomonas oryzae pv oryzae (Xoo) is a serious disease as there is no
chemical control is available against the Xoo pathogen. In view of this, deployment of host
plant resistance is the only approach for the management BB. As many as 10 pathotypes of
Xoo are prevalent in the Punjab state. Moreover, a single gene is not effective against all the
prevalent pathotypes. The quick neutralization of the resistance by the fast evolving bacteria
necessitated the augmentation of BB resistance
Recent biotechnological developments involving the use of DNA markers for efficient and
precise selection offer ways to pyramid resistance genes in desired backgrounds. In view of
the above scenario, efforts were directed towards development of rice varieties possessing
durable BB resistance (gene pyramiding), high yield, shorter growth duration and
acceptable grain quality in a sequential manner. The different BB pyramided gene
combination lines (xa5+xa13, xa5+Xa21, xa13+Xa21 and xa5+xa13+Xa21) in the
background of landmark rice cultivar PR 106 (developed under the ARBN funded
programme) were used as donors for BB resistance breeding. The segregating generations
were thoroughly phenotyped under artificial inoculation conditions using well characterized
virulent pathotypes in the field for BB and also selections were made for other
morphological traits. The systematic BB resistance breeding efforts were initiated in the late
70’s and continued later, resulted in the development and release of series of varieties which
kept the pathogen at bay for the last more than three decades. Through conjunctive use of
conventional and biotechnological techniques, bacterial blight resistance materials were
developed.
As a result of concerted and systematic breeding efforts, since 2013, five varieties of non-
Basmati rice (PR121, PR122, PR123, PR124, PR126 and PR127) and three of Basmati rice
(Punjab Basmati 3, Punjab Basmati 4 and Punjab Basmati 5) have been developed and
released in the Punjab state. All these varieties except PR126 resists the attack of all the 10
presently prevalent pathotypes of BB pathogen in the Punjab state. These varieties have
collectively covered an area of 68.5 percent in the state with PR121 being the most popular
variety covering 32 percent. All these varieties on account of shorter duration and high yield
possess higher per day productivity thereby yielding mor per unit area per unit time and per
unit of inputs and resources which is benefitting the farmers as well as the agro-ecosystem.
These have less biomass, thus paddy residue management is easier.
Key words: bacterial blight, gene pyramiding, resistance, MAS.
The 6th International Conference on Bacterial Blight of Rice
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Isolation and Screening of Promising Bacteriophages to Control Bacterial
Leaf Blight Disease on Rice Caused by Xanthomonas oryzae pv. oryzae,
Nguyen Thi Thu Nga1, Nguyen Thi Truc Giang1, Tran Minh Nho1, Dan Van Bao1,
Doan Thi Kieu Tien1, Pham Van Kim1, Kaeko Kamei2, Jeffrey B. Jones3
1College of Agriculture, Can Tho University, Viet nam; 2Kyoto Institute of Technology, Japan 3Department of Plant Pathology, University of Florida, USA
Bacterial leaf blight disease caused by Xanthomonas oryzae pv. Oryzae (Xoo), is a
serious disease on rice which causes yield loss up to 50% (Mew, 1992). In the world,
using bacteriophages (phages) as biocontrol agents (BCAs) to pathogenic bacteria
have been studied broadly (Gill and Abedon, 2003; Balogh and Jones, 2003;
Obradovic et al., 2004; Iriarte et al., 2007). The aims of study survey the presence of
phage in the nature such as soil and leave to improve methods for bacteriophage
isolation and survey the parasitic efficiency to host bacterium Xoo in vitro as well as
test the effect of bacteriophage in controlling disease in the net-house and field
condition. The results show that: 1) Using the direct and enrichment method for
bacteriophage isolation, there were 107 bacteriophages isolated from 62 Xoo strains
from 6 provinces of the Mekong delta of Vietnam (i.e. An Giang, Dong Thap, Kien
Giang, Can Tho, Hau Giang, and Soc Trang); 2) Evaluation of the host range of
phages on 62 strains of Xoo, the result indicated that phages with coded ΦxaVL12,
ΦxaDT63c, ΦxaHG48b, ΦxaDT60b, ΦxaAG68a could lysis more than 45 Xoo strains,
and the bacterial strain XaAG73 revealed the most sensitive strain which is lysed by
almost isolated bacteriophages; 3) Comparison of the plaque diameters of ΦxaVL12,
ΦxaDT63c, ΦxaAG68a, ΦxaHG48b, ΦxaDT60b on the bacterial strain XaAG73,
phage ΦxaDT60b showed the largest plaque than other phages; 4) Evaluation of the
effect of bacteriophage in controlling bacterial leaf blight disease caused by Xoo in the
net house conditions, five phages (ΦxaVL12, ΦxaHG48b, ΦxaĐT60b, ΦxaĐT63c,
ΦxaAG68a) showed effect in reduction of bacterial leaf blight infection, and phage
ΦxaDT60b exposed the most effect in disease reduction by spraying phage suspension
(108 pfu/ml) on the leaf surface before and after pathogen inoculation; 5) In field
condition, comparison of the efficacy of 4 phage treatments i.e ΦxaDT60b (107
pfu/ml), ΦxaDT60b (108 pfu/ml), phage mixture (107 pfu/ml and 108 pfu/ml) with
bactericide (Starner) and control treatment, the data revealed that all phage treatments
showed efficacy in disease reduction, and the treatment ФxaDT60b (108 pfu/ml), Mix
(108 pfu/ml) expressed better disease protection and higher yield than those of the
treatment ФxaDT60b (107 pfu/ml) and Mix (107 pfu/ml), and similar to the
bacteriocide treatment Starner 20WP.
Keywords: bacterial leaf blight, bacteriophage, rice, Xanthomonas oryzae pv. Oryzae
The 6th International Conference on Bacterial Blight of Rice
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Characterization of Bacteriophages Infecting Xanthomonas oryzae pv.
oryzae
Rejeki, Desi1,2, Addy, Hardian Susilo2,3, Narulita, Erlia2,4
1Graduate School of Biotechnology, University of Jember 2Center for Development of Advanced Sciences and Technology (CDAST), University
of Jember 3Department of Plant Protection. Faculty of Agriculture, University of Jember 4Department of Biology Education, Faculty of Teacher Training and Education,
University of Jember
Bacterial leaf blight (BLB) is a disease of rice in rice-producing countries including
Indonesia and attack rice in all stages of growth. The BLB is caused by Xanthomonas
oryzae pv. oryzae (Xoo) with the symptoms of grayish color and slightly wet on both
sides of the leaf and part of the side. In the advanced, crop production will be
decreased up to 50-70%. Recently, the effective efforts to overcome the problem by
using resistant varieties, antibiotics, sanitation, and antagonistic combinations;
however, the ability of the pathogen to forms new virulent pathotypes is noteworthy.
An alternative by utilizing bacteriophages as biological control agents could be used
because of their specific characteristics to their bacterial hosts. This research aimed to
obtain some information about the characterization of bacteriophage particles and
bacteriophage biological characters. The result showed that two bacteriophages had
been isolated from soil in Arjasa Jember and soil in Gadingan Situbondo, namely
phage XooAT (from Arjasa), and phage XooGT (from Gadingan) with similar plaques
morphology. The two phage isolates were inactivated at 80 ºC, and stable at pH within
the range of 6 to 8. The phage XooAT has a genome size of approximately 39 kb,
while phage XooGT had a genome size 38 kb and were differentiated into some types
by their EcoRV and XbaI restriction fragment patterns. According to the nuclease
pattern of nucleic acid, both phages are double stranded deoxyribose nucleic acid
(dsDNA) viruses. Moreover, protein profile on SDS-PAGE showed that similar
protein bands were appear on polyacrylamide gel. Phage biocontrol in vitro assay
showed that both phages significantly reduced the growth of BLB pathogen in the
liquid culture at MOIs between 0,01 and 10 indicating that both phages potentially,
are able to biological control BLB disease in rice.
Keywords: bacteriophage, Xanthomonas oryzae pv. oryzae, bacterial leaf blight,
phage therapy
The 6th International Conference on Bacterial Blight of Rice
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Biological Control of Bacterial Leaf Blight of Rice by Bacillus Strains in the
Mekong Delta: Current Status and Future Prospects
Tran Vu Phen1, Tsutomu Arie2, Huynh Van Nghi1, Nguyen Chi Thuc1,
Do Van Chung1, Nguyen Huu Thinh1, Tran Bao Ngan1
1Department of Plant Protection, College of Agriculture, Can Tho University, Vietnam 2Tokyo University of Agriculture and Technology, Japan
Bacterial leaf blight (BLB) of rice caused by Xanthomonas oryzae pv. Oryzae (Xoo) is
among the most devastating rice diseases that occur globally, including the Mekong
Delta of Vietnam. Farmers who are well aware of the harmful effects of pesticides still
heavily rely on plant protection chemicals. Among many efforts to manage this
disease, biological control using beneficial bacteria, especially Bacillus spp. Has been
considered as a prospective tool.
During 2012-2018, the research results at Can Tho University have recorded some
promising Bacillus strains, belong to B. subtilis, B. Amyloliquefaciens, Brevibacillus
brevis, ... which have been showed high antagonistic potential in vitro (radius of
inhibition zone 11-13.5 mm) and effective in suppressing BLB under net house
conditions or farm level field plots (BLB disease suppression 60-70%, equivalent to
common chemical bactericides, i.e. oxolinic acid, pronopol, at recommended
concentration). The promising Bacillus strains have been mass multiplied and
processed to powder (talc based substrate) or liquid (DSM-PVP) formulations. Shelf-
life stability tests of formulated bacteria were performed under room temperature
storage conditions showed that Bacillus spp. Remained stable over the period of four
to six months (5x108 cfu/ g or ml). The formulation was then tested against Xoo in in
vitro or net house conditions and the efficacy results revealed that the formulation
process did not affect the biocontrol potential of these strains. The evaluation of
formulations against BLB under field conditions showed that when applying leaf
sprays, 3 day intervals from 5% heading (seven sprays in total) resulted in reducing
bacterial leaf blight severity 63.40-73.48 %, equal to that of farmers’ practices
(Starner 20WP, 1.25‰, four sprays) and increase of grain yield over non-inoculated
plots.
Bacillus spp. Which is known to own diverse antagonistic mechanisms against Xoo,
can survive unfavourable conditions as endospores and are expected to be long-term
survival in the natural environment after being applied. The bioformulation based on
Bacillus spp. Can be stored long-term and maintain stable effectiveness. Additionally,
the suitability of technology should be taken into account to develop a stable and
effective and Bacillus spp. Should be a potential biocontrol agent for
commercialization to eco-friendly manage the BLB in the near future in the Mekong
Delta.
Keywords: Bacillus, bacterial leaf blight, biocontrol, bioformulation
The 6th International Conference on Bacterial Blight of Rice
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Eco-friendly Management of Bacterial Leaf Blight Disease of Rice in
Kuttanadu
Zacharia, R.M and Yohannan, A
Rice Research Station, Moncompu, Alappuzha, Kerala, India
The bacterial disease of rice caused by Xanthomonas oryzae p.v. oryzae remains as a
major production constraint causing a grain loss of 6-60%, in the below mean sea level
tracts of Kuttanadu, the rice bowl of Kerala state, India. This disease is known to occur in
an epiphytotic proportion almost every year in the additional crop season from June to
August due to the conducive weather condition with an annual mean temperature of
26.6C, annual rainfall of 3000 mm and mean relative humidity of above 85%. Annual
flooding also favours its occurrence.
Development of resistant strains of the pathogen is causing serious problems in
formulating full proof control. The policy of the State government to promote organic
cultivation of all crops is not permitting cultivation of transgenic crops. Improper and
untimely use of antibiotics like streptocycline seems to be less effective under field
conditions. It has become necessary to search an option for antibiotics for BLB control.
Mary (1996) reported the effectiveness of a curative spray with cowdung supernatant @
20g/l. Thus, a study was framed using several organic solutions, chemicals with
sterilizing effect, plant extracts, homoeopathic drugs with bactericidal properties.
In vitro studies were conducted using the agar diffusion method. Treatments showing
higher zone of inhibition were selected for the first in vivo pot culture study under CRD.
Highly susceptible variety MO-4 (Bhadra) that gave a score of 9 under artificial
inoculation was selected as the variety. Leaf clipping method was used for artificial
inoculation. Common checks were maintained with Strepto G (recommended control) and
Streptomycine sulphate (check). Two post inoculation sprays were given at 42 DAS and
62 DAS for the first experiment. In the second experiment with 16 treatments, one pre
inoculation spray and a post-inoculation spray were given at 38 DAS and 60 DAS.
Disease severity and yield were recorded at 120 DAS.
The treatments were found to be significantly different for both experiments. For the first
one, Thuja 30P (homeopathic drug) gave the highest disease control. This was on par
with Panchagavya (organic solution), potassium permanganate 20% and Pseudomonas+
cowdung supernatant. In the case of yield, the first two treatments were on par with
potassium permanganate 20%. In the nutrient analysis of harvested straw boron content
was increased in all the treatments and was indirectly related to chaffness of grains. In the
second experiment, disease severity was found to be significantly reduced in all the
treatments. Thuja 30P, potassium permanganate 20%, neem leaf extract, Pseudomonas,
Pseudomonas+ cowdung supernatant, Panchagavya, Badi Aga, cowdung supernatant
were found to be effective in reducing disease severity. Thuja gave the highest yield.
Treatments like Panchagavya, potassium permanganate 20%, Pseudomonas,
Pseudomonas+ cowdung supernatant, Asafoetida, Jeevamrutham also gave a good yield.
Panchagavya (organic solution) and Thuja 30P (homeopathic drug) were found to be
promising for reducing the disease severity of BLB and for getting higher yield in rice.
Keywords: Bacterial, disease, rice
The 6th International Conference on Bacterial Blight of Rice
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Defense Biochemical Alterations in Rice Leaves on Induced Resistance
against Xanthomonas oryzae pv. oryzae
Toan Le Thanh1,2, Kanjana Thamanu3, Hideo Nakashita4, Sopone Wongkaew2 and
Natthiya Buensanteai2
1Department of Crop Protection, College of Agriculture, Can Tho University, Viet
Nam; 2School of Crop Production Technology, Institute of Agricultural Technology,
Suranaree University of Technology, Thailand; 3Synchrotron Light Research Institute, Thailand; 4Faculty of Bioscience, Fukui Prefectural University, Japan
Bacterial leaf blight (BLB) disease caused by Xanthomonas oryzae pv. Oryzae (Xoo)
is the most frequent disease in rice fields. BLB management is mainly focused on
methods of using agrochemicals and resistant cultivars to reduce the initial inoculum
and enhance rice health. Induced resistance, based on the increased expression of
genes in rice plants, could elicit natural defense mechanism in rice. The induced rice is
able to resist an attack of virulent pathogens by enhancing an array of rapidly
expressed defenses upon infection. The elicitors including SA, ascorbic acid (AA),
benzo (1,2,3)-thiadiazole-7-carbothionic acid S-methyl ester or acibenzolar-S- methyl
(ASM), chitosan, BTH, ZnSO4.7H20, soluble silicon have been extensively evaluated
against several plant diseases. The induced resistance of rice against Xoo by priming
with exogenous 1,2-Benzisothiazol-3 (2H)-one 1,1-dioxide (BIT) has not yet been
characterized. Therefore, the objective of the study was to characterize the defense
responses of rice plants against LB after treatment with exogenous BIT at a
concentration of 2 mM and challenge inoculation with Xoo by monitoring
biochemical changes associated with plant defense mechanisms. The experiment was
conducted with a completely randomized design, five replications. Rice seeds cv.
KDML105 were soaked thoroughly with 100 ml of the solution of BIT at a
concentration of 2 mM. Rice seeds treated were planted in 35 cm-plastic pots
containing soil. The rice plants were further treated by foliar sprays with the solution
of 2 mM BIT until it ran off, at 15, 30 and 45 days after planting (DAP). Six matured
leaves of fifty-day-old rice plants per one pot were randomly chosen and inoculated
by cutting leaf tips, approximately 3 cm from the leaf tip, and dipped into a Xoo
suspension at the density of 1x108 cfu ml−1. Leaf samples including above or below
leaf were collected at 7 DAI and put into an oven at 60oC for 2-3 days, then ground
into fine powder by mortars and pestles. Equal weights of powder samples were taken
The 6th International Conference on Bacterial Blight of Rice
39
and analyzed by ATR-Fourier transform infrared (ATR-FTIR) spectroscopy. The
results showed that BIT-induced rice leaves had many intense peaks which
represented defensive carbohydrates, proteins, and lipids. At leaves above the Xoo-
inoculated leaf, exogenous BIT treatment had importantly spectral shifts than those of
BIT-non treated control at the peaks of lipid and protein, such as 2920, 2851, 1736
cm-1, and the structural change of amide I from alpha helix type at the peak of 1655
cm-1 to β-sheet type at 1636 cm-1. At rice leaves below the Xoo-inoculated leaf, its
Fourier transform infrared peak assignments of the BIT-induced treatment had
significantly spectral peaks than those of the control treatment at some vibrational
peaks of lipid and carbohydrate, such as 2920, 2851, 1319, 1103 and 1040 cm-1. Three
vibrational peaks such as 1319, 1103 and 1040 cm-1 could be used as biomarkers of
induced resistance in rice. In this study, the elicitor of BIT reduced leaf blight severity
in rice plants by approximately 34.82%.
Keywords: BIT, leaf blight, Fourier transform infrared spectroscopy, and induced
resistance.
The 6th International Conference on Bacterial Blight of Rice
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Session V: Molecular Interaction Between Host and X. oryzae pv. oryzae
Xanthomonas oryzae – Triggered Production of Atypical Rice Small RNAs
During Infection
Reshetnyak G.*1, Jacobs J.*1-2, Auguy F.1, Claude L.1, Sciallano C.1, Medina C.1,
Perez-Quintero A.1, Thomas E.1 , Rivas JC.1, Bogdanove A.3, Dievart A.4 , Koebnik
R.1, Szurek B.1, Brugidou C.1, Lacombe S.1, Cunnac S.1
1IRD,CIRAD, Univ Montpellier, IPME, Montpellier, France 2Department of Plant Pathology, Infectious Disease Institute, Ohio State University,
Columbus, OH, United States. 3Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant
Science, Cornell University, Ithaca, NY, United States 4CIRAD, UMR AGAP, Montpellier, France
Eukaryotic regulatory small RNAs (sRNA) range from 20 to 24 nucleotides and are
ubiquitous in plants. As mediators of transcriptional and post-transcriptional gene
silencing, they play are important in regulating growth, development and stress
responses. In the plant cell, sRNAs are mostly endogenous but can derive from viral
sequences or be delivered by interacting organisms. sRNA biogenesis begins with the
cleavage of double-stranded RNA precursors by a dicer-like enzyme (DCL). The
resulting sRNA duplexes are then protected from degradation by HEN1-mediated
methylation, and the mature guide sRNA strand is incorporated into the RNA-induced
silencing complex (RISC). RISC targets complementary nucleotides to dampen gene
expression. Early insight on sRNAs in plants revealed their role in antiviral defense
and they are now extensively studied in response to diverse pathogens. Here we
describe a novel class of sRNA in rice (Oryza sativa) associated with foliar diseases
caused by Xanthomonas oryzae pathovars. Analysis of our high-throughput sRNA
sequencing data suggests that Xanthomonas-induced small RNAs (xisRNAs) possess
features of regulatory sRNA and may target genes involved in plant immune signaling
or sRNA production. xisRNAs biogenesis is still enigmatic but we showed that it
depends on some canonical sRNA pathways components. In addition, transcription of
protein-coding loci overlapping the genomic sequences of xisRNAs is required for
their accumulation. Our results further indicate that X. oryzae uses its virulence
arsenal of type III effectors for maximal xisRNA accumulation. Finally, we will report
on our efforts to address the significance of these xisRNA during disease.
Keywords: small RNAs, RNA silencing, RLCK, Xanthomonas oryzae, rice
The 6th International Conference on Bacterial Blight of Rice
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The RpoN2-PilRX System Regulates Type VI Pilus-dependent Motility and
is Required for Virulence in Xanthomonas oryzae pv. Oryzae
Yu C1, Yang C-H2, He CY1
1State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of
Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; 2Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee,
WI 53211, USA
Type IV pili (T4P), a special class of bacterial surface filaments plays a crucial role in
bacterial interactions with host and pathogenesis, surface adhesion, motility, and
biofilm formation. The T4P secretion machinery is made up of 4 subcomplexes: (i)
the outer membrane subcomplex formed by the dodecameric ring of PilQ and the pilot
in PilF, (ii) the inner membrane platform, made up of PilC, PilM, PilN, PilO and PilP,
(iii) the ATPases PilB, PilT and PilU, and (iv) the pilus filament, a polymer of the
major pilin, PilA, and minor pilins. The genomic sequence of Xanthomonas oryzae pv.
oryzae (Xoo) strain PXO99A showed 13 regulons containing 26 genes (PilAX-PilZX)
coding for T4P structural components and putative regulators. How the T4P system is
regulated and how it is related to bacterial pathogenesis are not well understood. Our
previous studies showed that alternative σ54 RpoN2 worked together with its
transcriptional activator FleQ to regulate flagellar motility through affecting flagellar
gene transcription, whereas RpoN2 regulated bacterial virulence in rice through a
FleQ-independent manner. In this study, the yeast two-hybrid (Y2H) and GST pull-
down assays revealed that RpoN2 directly and specifically interacted with PilRX, a
homolog of the response regulator PilR of the two-component system (TCS) PilS/PilR.
A consensus RpoN2 binding sequence NNGGN10GCNN was identified in the
promoter sequences of 13 T4P gene transcriptional units that were determined by RT-
PCR analysis. EMSA assays confirmed direct binding of RpoN2 to the promoters of
pilAX, pilCX and pilRX. Each gene deletion in pilAX, pilCX, and pilRX resulted in
significantly reduced sliding and swimming motility and virulence in rice. Taken
together, the findings from the current study suggest that RpoN2-PilRX system
regulates bacterial motility and pathogenesis which might be via regulating T4P gene
transcription in Xoo.
Keywords: σ54, PilRX, motility, type VI pilus, virulence, transcriptional regulation
The 6th International Conference on Bacterial Blight of Rice
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Cyclic Di-GMP Signaling Regulation of Virulence in Xanthomonas oryzae
pv. oryzae
Yang FH1, Xue DR1, Tian F1, Hutchin W2, Yang C-H3, He CY1
1State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of
Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; 2Department of Biology, Carthage College, Kenosha, WI 53140-1994, USA; 3Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee,
WI 53211, USA
Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight of rice, one of the
most devastating bacterial diseases of this staple crop worldwide. Xoo produces a
range of virulence factors to facilitate its pathogenesis in rice, however, the regulatory
mechanisms of Xoo virulence expression have been not fully elucidated. Further
insight into signaling pathways involved in regulation of virulence will contribute to
the understanding of Xoo pathogenesis, and effectively allow the development of
prevention strategies and control of pathogenic infection in rice. Our recent studies
showed that virulence factor production in this pathogen was mediated by the
regulation of the second messenger nucleotide cyclic dimeric guanosine
monophosphate (c-di-GMP). The genome encodes a set of GGDEF, EAL, HD-GYP,
and PilZ domain containing proteins with diverse signal sensory domains for c-di-
GMP synthesis, hydrolysis, and binding. Bioinformatic, genetic, and biochemical
analysis has identified an array of diguanylate cyclases (DGCs) and
phosphodiesterases (PDEs), as well as degenerate GGDEF/EAL and PilZ domain
proteins, along with a transcription regulator. These signaling components have been
characterized to regulate various bacterial cellular processes, such as virulence,
exopolysaccharide (EPS) production, biofilm formation, and motility, at
transcriptional, post-translational, and protein-protein interaction levels. In this present
review, we summarized the findings that have revealed the importance and complexity
of c-di-GMP signaling in regulating bacterial virulence in Xoo, highlighting key
signal elements also found in other close Xanthomonas species, also discussing the
possible existence of a complicated multifactorial network between the DGCs, PDEs,
receptors and effectors. These findings lay the groundwork for future experimentation
to further elucidate c-di-GMP regulatory circuits involved in the regulation of
bacterial pathogenesis.
Keywords: c-di-GMP; signaling; regulation; virulence; Xanthomonas species
The 6th International Conference on Bacterial Blight of Rice
43
Combined Transcriptome and Proteome Analysis of the Pathogenicity-
Activated Xanthomonas oryzae pv. oryzae
Kim S1, Kim JG1, and Kang LW2
1Genomics Division, National Institute of Agricultural Sciences, Rural Development
Administration (RDA), Jeonju 03016, Republic of Korea; 2Department of Biological Sciences, Konkuk University, 120 Neungdong-ro,
Gwangjin-gu, Seoul 05029, Republic of Korea
Our group developed the in vitro assay system to study time-resolved genome-wide
gene expression of Xoo. The in vitro assay system was used for the combined
transcriptome and proteome study of Xoo upon the pathogenicity activation via the
initial interactions with rice leaf extract (RLX). Genome-wide gene expression of Xoo
upon pathogenicity activation was systematically studied in both transcription and
translation at multiple time points, which provides a useful tool to study pathogenic
gene expression at the initial stage of pathogen-host interaction. Chemotaxis and
flagella biosynthesis-related genes showed simultaneous expression of mRNA and
protein, in which transcription and translation are tightly coupled. Genes related to
inorganic ion transport and metabolism including iron and phosphate showed 30 – 120
min delayed translation after transcription. Although transcription and translation
could occur simultaneously in bacteria, genes of different functional categories
showed variable time gaps between the peaks of transcriptional and translational gene
expression.
Keywords: plant–pathogen interactions, proteomics, transcriptome, time-resolved
genome-wide gene expression, Xanthomonas oryzae pv. oryzae, pathogenicity
The 6th International Conference on Bacterial Blight of Rice
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Xanthomonas oryzae pv. oryzae T3SS-effector XopF Interacts with Multiple
Rice Targets to Subvert the Immune Responses during Bacterial Blight
Development
Kalyan K. Mondal and Aditya Kulshreshtha
Division of Plant Pathology, ICAR-Indian Agricultural Research Institute, New Delhi
110012, India
Bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo), severely affects rice
production globally. Xoo depends on effector proteins for its successful proliferation
into the rice plants. These effectors are secreted directly into the rice cells through a
type 3 secretion system (T3SS). We previously documented that XopF effector is
essential for bacterial virulence, spread inside the plant and suppresses the rice PTI.
Now it is important to know the possible interactor(s) for the XopF in rice. The
present study is thus aimed at searching the rice interactor(s) for XopF employing
yeast two-hybrid (Y2H) system. The full-length xopF gene (accession: KF939317)
was PCR amplified and subsequently cloned into yeast bait vector in fusion with
GAL4 DNA binding domain. Before library screening, we verified the non-toxic and
non-autoactivating nature of XopF on the nutritional dropout medium. In order to
develop the cDNA library, total RNA was extracted from healthy and infiltrated (with
Xoo race 4) rice leaves (cv pusa basmati 1) and pooled together before cDNA
preparation. The cDNA library was cloned into yeast prey vector pGADT7 in fusion
with the GAL4 DNA-activation domain. The library was transformed into yeast Y187
strain. The transformed library was screened using XopF as bait. The mated positive
colonies were selected, and the serial dilution was performed on QDO medium. The
cDNA library fragments from the positive colonies were PCR amplified, cloned and
sequenced. Based on sequence data, we identified two key interactors, namely
chloroplastic photosystem I subunit V (Accession No. XP_015611871) and
cyclophilin II (Accession No. GQ848065). Both these interactors are known to play a
role in the suppression of immune responses in plant. XopF targets the plant
photosystem I supercomplex (with light-harvesting complexes I and II) to interfere
with the normal photosynthesis leading to breakdown of resistance. Whereas, plant
cyclophilin is a well-known target for bacterial pathogens to suppress plant immunity.
The present study is thus concluded that XopF targets multiple interactors with the
primary aim to subvert the immune responses of plants through suppressing
photosynthate via photosystem I as well as through compromised immune protection
system like cyclophilin in plants. This insight will be useful in exploring strategies for
disease resistance.
Keywords: Xanthomonas, T3SS, XopF, effector
The 6th International Conference on Bacterial Blight of Rice
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Xylose-dependent hrp Gene Expression in Xanthomonas oryzae pv. oryzae
Tsuge, S. and Ikawa, Y.
Kyoto Prefectural University, Kyoto, Japan
hrp genes encoding components of the type III secretion system are indispensable for
virulence of Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight
of rice. Expression of hrp genes is induced only in plants or certain nutrient-poor
media, so called hrp-inducing media. The expression of hrp genes is regulated by two
key hrp regulators, HrpG and HrpX; HrpG, predicted to be an OmpR-type response
regulator of a two-component signal transduction system, regulates hrpX, and HrpX, a
member of an AraC-type transcriptional activator family, regulates other hrp genes.
Besides them, several regulators or regulatory cascades that are involved in the
regulation of hrp genes have been reported, though the whole feature of the regulatory
network still remain unclear. We found that hrp gene expression of X. oryzae pv.
oryzae is specifically induced when xylose is added in the hrp-inducing medium, and
that the second key hrp regulator HrpX abundantly accumulated only in the presence
of xylose, which causes the induction of HrpX-regulated hrp gene expression,
although hrpX expression is independent on sugar source. Random transposon
mutagenesis revealed that a LacI-type transcriptional repressor XylR is involved in the
negative regulation of hrp gene expression. In the mutant lacking xylR HrpX
accumulation and the expression of hrp genes were highly induced even under the
xylose-free condition. XylR also negatively regulated xylan/xylose metabolism-
related genes by binding to the cis element located upstream of the target genes, and
the negative regulation was cancelled in the presence of xylose or in the absence of
XylR. The mutant deficient in xylose isomerase, which converts xylose to xylulose in
the first step of the xylose metabolism, showed similar hrp gene expression to the wild
type in the medium containing xylose, suggesting that xylose, not its metabolites,
functions as the substrate to inactivate XylR. Furthermore, the introduction of amino
acid substitution in the substrate-binding domain of XylR caused less hrp gene
expression even in the presence of xylose, and the virulence of the mutant in rice
plants was weaker than that of the wild type. The results suggest that, in X. oryzae pv.
oryzae, expression of hrp genes and xylan/xylose metabolism-related genes are
concomitantly and negatively regulated by XylR, and that, by inactivating XylR,
xylose plays an important role in virulence of the bacterium.
Keywords: Xanthomonas oryzae pv. oryzae, hrp, type III secretion system,
transcriptional regulator, xylose
The 6th International Conference on Bacterial Blight of Rice
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Session VI: Integrative Genomics, Proteomics – Effectors, Epigenetics
of X. oryzae pv. oryzae
Bioinformatic Approaches to Uncover Genetic Acquisitions Associated
with Epidemic Populations of Xanthomonas oryzae pv. oryzae
Alvaro L Perez-Quintero1, Rex Steele1, Jonathan Jacobs,1,2 Jan Leach1
1.Department of Bioagricultural Sciences and Pest Management, Colorado State
University, Fort Collins, CO, United States
2.Department of Plant Pathology, Infectious Disease Institute, Ohio State University,
Columbus, OH, United States
The sudden appearance and rapid spread of pathogen populations can be associated to
changes in environmental conditions or to exposures to susceptible hosts (as when
introduced to a new geographical region). However, often, these spreads are also
associated to genetic changes in the population: mutation or acquisition of new
genetic features, that confer the population a fitness advantage. Currently, bacterial
genomic data is being generated at exponential proportions, and much of it is
underexploited. We are developing strategies to integrate methods for genomic
analyses in a way that given a set of bacterial genomes and any trait of interest, a user
can obtain possible genes or genomic regions associated to said trait. We used this
approach to study a population of Xanthomonas oryzae pv oryzae (Xoo) obtained from
field experiments where breakdown of resistance mediated by the R genes Xa7 and
Xa1 was shown. Particularly, some strains of race 9b were able to infect Xa7-carrying
plants without losing the cognate avrXa7 gene. We applied our genome association
pipeline to a set of newly sequenced genomes from this population as well as all
available Xoo genomes, thus identifying candidate genes associated with resistance
breakdown, including a candidate interfering TAL effector. We are currently applying
this pipeline to other emerging and epidemic populations of Xanthomonas.
Keywords: Xanthomonas, Xa gene, TAL effector, genomic analyses
The 6th International Conference on Bacterial Blight of Rice
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BDSF is the Predominant In-Planta Quorum-Sensing Signal Used During
Xanthomonas campestris Infection and Pathogenesis in Chinese Cabbage
Diab Abdelgader Abdeen, Cao Xue-Qiang, Song Kai, Zhou Lian, He Ya-Wen
State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of
Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai
Jiao Tong University, Shanghai 200240, China
Molecules of the diffusible signal factor (DSF)-family are a class of quorum sensing (QS)
signals used by diverse Gram-negative bacterial pathogens. Studies during the last two
decades have outlined the structural, signaling, biosynthetic pathway and natural turnover
properties of DSF-family signals in the phytopathogen Xanthomonas campestris pv.
campestris (Xcc). However, all of the DSF-family signals characterized from Xcc to date
were derived from in vitro laboratory-based cell culture. The in planta QS signal used
during Xcc infection and pathogenesis remains to be elucidated. To answer this question, we
presented the following results in this study: (1) We first utilized XYS medium
supplemented with cabbage hydrolysate to mimic Xcc growth conditions in planta. We
found that the dominant signal produced in these conditions was BDSF, a member of DSF-
family signals. (2) We then examined the effects of various plant-derived compounds (15
non-branched-chain amino acids, 3 branched-chain α-ketoacids, 3 carboxylic acids, 5 plant-
derived organic acids, 6 plant hormones, and 8 plant-derived phenolic compounds) on the
biosynthesis of DSF-family signals in vitro. Several compounds were found to promote
BDSF biosynthesis. (3) The further Western blotting analysis showed that plant hormone
ABA and trans-2 hydroxycinnamic acid significantly affected the expression of BDSF
synthase RpfF. The other compounds probably are used as a carbon source to promote
BDSF biosynthesis. (4) We established an Xcc ΔrpfB-Chinese cabbage infection model and
a UPLC-TOF-MS-based assay optimized for DSF-family signals. We found that BDSF
comprised more than 70% of the DSF-family signals present in infected cabbage tissue.
Further analysis showed that BDSF is functional quorum sensing signal in Xcc. BDSF at a
concentration of 2.0 μM induced both protease activity and engXCA expression. The
induction is dependent on the signal receptor RpfC.
This is the first report to directly show that BDSF is the major in planta QS signal used
during the Xanthomonas infection process. It provides a better understanding of the
molecular interactions between Xcc and its cruciferous hosts during infection, and also
identifies the logical target for designing strategies to counteract BDSF signaling and thus
infection.
Keywords: Xanthomonas, quorum sensing, BDSF.
The 6th International Conference on Bacterial Blight of Rice
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Getting into the Weeds: How Monitoring Xanthomonas Species Outside the
Paddy can Inform Crop Management and Our Understanding of Pathogen
Evolution
Lang, J.M.1,2, Pérez-Quintero, A.L.1,2, Koebnik, R.2, DuCharme, E.1, Sarra, S.3,
Doucoure, H.4, Keita, I.4, Ziegle, J.5, Jacobs, J.M.1,2,6, Oliva, R.7, Koita, O.4, Szurek,
B.2, Verdier, V.1,2**, Leach, J.E.1
1Department of Bioagricultural Sciences and Pest Management, Colorado State
University, Fort Collins, CO, USA; 2IRD, Cirad, Université de Montpellier, IPME,
Montpellier, France; 3Centre Régional de Recherche Agronomique de Niono, Institut
d’Economie Rural (IER), Bamako, Mali; 4Laboratoire de Biologie Moléculaire
Appliquée, Université des Sciences Techniques et Technologiques, Bamako, Mali; 5Pacific Biosciences, Menlo Park, CA; 6Department of Plant Pathology, Infectious
Disease Institute, Ohio State University, Columbus, OH, USA; 7International Rice
Research Institute, Los Baños, Philippines.
Xanthomonas oryzae (Xo) are globally important rice pathogens. Virulent lineages
from Africa and Asia and less virulent strains from the US have been well
characterized. X. campestris pv. leersiae (Xcl), first described in 1957, causes bacterial
streak on the perennial grass, Leersia hexandra, and is a close relative of Xo. L.
hexandra, a member of the Poaceae, is highly similar to rice phylogenetically, is
globally ubiquitous around rice paddies, and is a reservoir of pathogenic Xo. We used
long read, single molecule, real time (SMRT) genome sequences of five strains of Xcl
from Burkina Faso, China, Mali and Uganda to determine the genetic relatedness of
this organism with Xo. Novel Transcription Activator-Like Effectors (TALEs) were
discovered in all five strains of Xcl. Predicted TALE target sequences were identified
in the L. perrieri genome and compared to rice susceptibility gene homologs.
Pathogenicity screening on L. hexandra and diverse rice cultivars confirmed that Xcl
are able to colonize rice and produce weak but not progressive symptoms. Overall,
based on average nucleotide identity, type III effector repertoires and disease
phenotype, we renamed Xcl to X. oryzae pv. leersiae (Xol) and propose using this
parallel system to improve understanding of the evolution of bacterial pathogenicity in
rice agroecosystems.
Keywords: Xanthomonas oryzae, Transcription Activator-Like Effectors (TALEs),
agroecosystem, cutgrass, rice
The 6th International Conference on Bacterial Blight of Rice
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Session VII: Biotech and Genome/Gene Editing
OsERF#123, a New Susceptibility Gene for Bacterial Blight of Rice
Hutin M1,3, Tran TT1, Belanto JJ2, Wang L3, Perez-Quintero AL14, Thomas E1,
Willmann MR3, Voytas DF2, Szurek B1, Bogdanove AJ2
1UMR IPME, IRD-CIRAD-Université Montpellier, Montpellier, France 2Department of Genetics, Cell Biology & Development and Center for Genome
Engineering, University of Minnesota, Mineapolis, United States of America 3Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant
Science, Cornell University, Ithaca, New York, United States of America 4Department of Bioagricultural Sciences and Pest Management, Colorado State
University, Fort Collins, CO, United States
Bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is a devastating
disease of rice, a crop that feeds more than half of the world’s population. Xoo
virulence critically depends on the transcription activator-like effector (TALE)-
dependent activation of specific host genes called susceptibility (S) genes. The number
of TALEs per strain varies from 9 to 16, with African strains, which form a distinct
genetic lineage, typically having fewer TALEs than Asian strains. While one or two
TALEs per strain generally act as major virulence factors, the relative contributions of
the other TALEs to Xoo pathogenicity is unclear. We sequenced the entire genomes
and compared the TALE repertoires of three African Xoo strains. We assessed the
individual contribution to pathogen virulence of 13 TALE variants represented in the
three strains and identified TalB as a new, major virulence factor. RNA profiling and
in silico prediction of TalB binding sites in rice revealed OsTFX1, a bZIP
transcription factor previously identified as a bacterial blight S gene, and OsERF#123,
which encodes a subgroup Ixc AP2/ERF transcription factor, as candidate targets.
Activation of OsERF#123 using gene-specific designer TALEs restored virulence to a
talB knockout strain, confirming OsERF#123 as a new bacterial blight S gene. We
have generated and are currently characterizing OsERF#123 promoter-edited and
OsERF#123 CDS deletion lines to further probe the role of OsERF#123 in
susceptibility and to understand its function in other contexts.
Keywords: Susceptibility genes, TAL effectors, Resistance, African Xoo
The 6th International Conference on Bacterial Blight of Rice
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Legal Framework for Genome Editing Approaches in Agricultural
Development
Sarah M Schmidt1, Boris Szurek2, Bing Yang3, Frank White4, Ricardo Oliva5, Wolf
Frommer1
1Heinrich Heine University, Düsseldorf, Germany, 2 Institut de Recherche pour le
Développment (IRD), Montpellier, France, 3 University of Missouri, St. Louis, US, 4
University of Florida, US, 5 International Rice Research Institute (IRRI), Los Banos,
Philippines
Genome editing, and especially CRISPR technology, are said to democratize and
revolutionize agricultural research. Many people believe in the potential benefits of
genome editing for food security. But what does it take to develop a genome edited
crop? Which legal requirements need to be followed? And what is the legal
framework for releasing a genome edited crops in countries in America, Europe, Asia
and Africa? Within the Healthy Crops research consortium, we are developing rice
varieties that are resistant against Bacterial Blight by genome-editing of the SWEET
promoters for smallholder farmers in Asia and Africa. One difficulty for developing
resistant crops using genome editing approaches is IP (Intellectual Property). I will
discuss our approach to obtain Freedom to Operate, that is to use patented technology,
within a humanitarian research project. Furthermore, I will present the regulatory
strategy for our research-for-development project as well as an overview of the current
legal frameworks for genome-editing in the EU, US, Australia, Argentina, Colombia,
Japan and other countries. Finally, I will provide insights into the ongoing decision
process in several Asian and African countries and discuss the difficulties of creating
a globally harmonized legislation on genome editing.
Keywords: Genome editing, CRISPR, bacterial blight, resistance, agriculture for
development
The 6th International Conference on Bacterial Blight of Rice
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Poster Presentations’ Abstracts
P01: Characterization of Xanthomonas oryzae Strains Causing Rice
Bacterial Diseases in Senegal: Towards the Identification of Genetic
Sources of Resistance to BLB and BLS
Hamidou Tall1,3, Kandioura Noba2, Boris Szurek3, Mathilde Hutin3 , Sébastien
Cunnac3, Valérie Verdier3
1Institut Sénégalais de Recherches Agricoles (ISRA), Bel Air, Dakar Sénégal 2 Département de Biologie végétale, Université Cheikh Anta DIOP de Dakar 3IRD, Cirad, Univ Montpellier, IPME, Montpellier, France
Bacterial diseases limit rice yield in Africa and thus threaten food security. Bacterial
Leaf Blight (BB) and Bacterial Leaf Streak (BLB) caused by Xanthomonas oryzae pv.
oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc), respectively, were
reported once in Senegal in the eighties but no isolate was collected. Resistance
breeding depends on adequate knowledge of the genetic diversity of pathogen
populations. The choice of BB and BLS resistance gene(s) should be made based
upon their effectiveness against the prevalent races of Xoo and Xoc in the region. As
no strains were collected in Senegal so far, no strategy has been pursued to control the
diseases.
To confirm the presence of X. oryzae in Senegal, we assessed the prevalence of BB
and BLS in different regions of the country. The main areas of domestic rice
production were surveyed between 2014 and 2016. Symptomatic leaf samples were
collected in the field and analyzed. Following bacterial isolation, a PCR multiplex
scheme confirmed the presence of Xoo and Xoc in different sites of each region. A set
of IRBB lines was used to identifying effective BB resistance genes and characterize
the races of Xoo in Senegal. We also evaluated the virulence of strains of Xoc and
Xoo on popular rice accessions to evaluate their level of resistance to these two
pathovars and their impact on the yield of these varieties. Finally, to potentially
connect Transcription Activator-Like Effector genes with pathogenicity/host range,
we profiled their genomic repertoire in Senegalese of Xoo and Xoc strains.
The use of rice cultivars with introgressed disease resistance I genes is currently the
best way to control BB disease with minimal environmental effects and cost. No rice
resistance gene has been reported to control BLS worldwide. Our results will
contribute to a more rational deployment of sources of genetic resistance to BB and
BLS in Senegal.
Keywords: Report, characterization, Senegal, bacterial diseases, rice, Xanthomonas
oryzae, control strategies
The 6th International Conference on Bacterial Blight of Rice
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P02: Pursuing Durable, Broad-Spectrum Resistance in Rice: Exploiting
Promoteromes, Effectors and MAGIC
Alejandra I. Huerta1,2, Emily Delorean1, Ana M. Bossa-Castro1, Bradley Tonnessen1,
Alvaro L. Perez-Quintero1, Chitra Raghavan3, Rene Corral1, Valerie Verdier1,4, Hei
Leung3, and Jan E. Leach1
1 Colorado State University, Fort Collins, CO, USA 2 North Carolina State University, Raleigh, NC, USA 3 International Rice Research Institute (IRRI), Los Baños, Philippines 4 IRD, Cirad, Univ Montpellier, IPME, Montpellier, France
Disease resistance is the foundation for managing many plant diseases, because
resistant varieties have the strongest impact with minimal environmental effects or
cost. Consequently, sources of broad-spectrum resistance (BSR), or resistance that is
effective against multiple and/or diverse pathogens is of particular interest. However,
achieving BSR depends on having effective resistance sources to introduce into elite
germplasm. Multi-parent Advanced Generation Inter-Cross (MAGIC) populations are
powerful tools for identifying resistance because they have high levels of
recombination and enhanced resolution relative to biparental populations. We
screened an indica rice MAGIC population developed from eight elite founders for
BSR to diverse strains of the rice bacterial blight and leaf streak pathogens
Xanthomonas oryzae pv. oryzae (Xoo) and X. o. pv. oryzicola (Xoc), respectively. In
addition, building on our hypothesis that durable disease resistance is attainable by
targeting key microbial virulence factors, we screened for resistance to Xoo strains
isogenic for the known and common virulence factor TAL7b. A combination of
genome-wide association studies and interval mapping analyses revealed a number of
loci that conferred BSR to both Xoo and Xoc, as well as resistance targeted at
TAL7b. These BSR QTL are excellent sources for durable, broadly effective
resistance in the field.
Keywords: broad-spectrum disease resistance, quantitative trait loci, MAGIC
population
The 6th International Conference on Bacterial Blight of Rice
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P03: Novel Sources of Race-Specific Resistance Gene against Bacterial
Blight of Rice in Green Super Rice Breeding Materials
Padilla JJ1, Vinarao R1,2, Sevilla MAL1, Nguyen MH1, Vera Cruz CM1, Ali J1, and
Oliva R1
1International Rice Research Institute, Los Baños, Laguna, Philippines 2Present Address: School of Agriculture and Food Sciences, University of Queensland,
St Lucia QLD 4072, Australia
Bacterial blight (BB) is one of the most economically important diseases of rice. It is
caused by the bacterium Xanthomonas oryzae pv. oryzae (Xoo). A number of major
qualitative genes conferring resistance I to BB have been mapped and functionally
characterized. Although broad-spectrum R genes are more durable in the field, it is
also important to look for other sources of genes for race-specific resistance in order
to slow down the degradation of deployed qualitative R genes. In this study, putative
sources of R genes against a particular race of the pathogen are being confirmed.
About 134 Green Super Rice (GSR) inbred lines generated from multi-cross of ten
New Rice for Africa (NERICA) varieties/lines were evaluated for their resistance to
14 differential strains of Xoo, representing the ten races of the pathogen population in
the Philippines. Out of the 134, 88 lines (65.7%) show resistance to the strain PXO339
(race 9a). This resistance can only be explained by the presence of known R genes
such as Xa23, xa5 or xa25, or novel alleles of these genes. Because of their good yield
performance, 43 lines from the resistant panel were genotyped using trait –based SNP
panel in Genotyping Services Laboratory (gsl.irri.org). Genotyping confirms the
absence of major gene Xa23 in all lines while detects the presence of xa5 gene in 24
lines. Resistance to PXO339 of remaining 19 lines, those without Xa23 and xa5, is
probably due to the presence of xa25. However, three different patterns of resistance
to all strains were observed from these 19 lines: (1) resistance only to PXO339 (race
9a); (2) resistance to PXO339 and to five other strains – PXO61 (race 1), PXO112
(race 5), PXO145 (race 7), PXO280 (race 8) and PXO341 (race 10); and (3) resistance
to all isolates except to PXO71 (race 4) and PXO99 (race 6). The variation in patterns
of resistance suggests that a novel gene or allelic variants of known R genes are
responsible for the resistance of these breeding materials to race 9a.
Keywords: Green Super Rice, breeding for resistance, race-specific resistance,
bacterial blight of rice
The 6th International Conference on Bacterial Blight of Rice
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P04: Over-expression of Defense-related Enzymes in Incompatible
Interactions Involving Rice Bacterial Blight Resistance Gene, Xa23 and
Five Pathotypes Xanthomonas oryzae pv. oryzae
Kamboj I, Hunjan MS, Lore JS* and Pannu PPS
Department of Plant Pathology, *Department of Plant Breeding and Genetics,
Punjab Agricultural University, Ludhiana, Punjab -141 004
Rice plant responds to attack by Xanthomonas oryzae pv. oryzae (Xoo) by activating
various defense responses. The resistance and susceptibility of crop is a character
dependent on activity of different defense related enzymes controlled by genes. Xa23
is broad-spectrum bacterial blight resistance gene identified from O. rufipogon. The
defense related enzymes including phenylalanine ammonia lyase (PAL), peroxidase
(POD), and polyphenol oxidase (PPO) are produced as a reciprocal action of infection
process by Xanthomonas oryzae pv. oryzae (Xoo) and play an important role in the
active defense mechanism of rice plant. In-planta multiplication and movement of
Xoo have a close relationship with expression of disease symptoms where lesion
length provides a measure of pathogen colonization of the rice leaf tissues. In the
current study, biochemical response of rice bacterial blight resistance gene, Xa23 was
evaluated under controlled conditions. Sixty days old plants of rice near isogenic line
IRBB23 carrying Xa23 gene and IRBB14 containing Xa14 gene (susceptible check)
grown in Conviron CMP650 plant growth chamber were clip inoculated with five
pathotypes (PbXo-4, PbXo-7, PbXo-8, PbXo-10 and Sgr-1001) of Xoo. The defense
related enzymes viz. PAL, POD and PPO were estimated from the advancing lesions
of the inoculated leaves. It was observed that all the three enzymes were over-
expressed in incompatible interactions (Xa23-PbXo-7, Xa23-PbXo-8 and Xa23-Sgr-
100). The activity of POD enzyme was found to be 19.0, 45.0, 63.9, 13.1 and 67.6
min-1g-1 fresh weight while activity of PPO enzyme was found to be 14.7, 33.9,
60.2, 11.9 and 72.3 min-1g-1 fresh weight in case of Xa23-PbXo-4, Xa23-PbXo-7,
Xa23-PbXo-8, Xa23-PbXo-10 and Xa23-Sgr-1001 interaction respectively after 96
hours of inoculation in both the cases. On the other hand, maximum activity of PAL
enzyme was observed to be 47.9, 198.2, 165.5, 37.0 and 177.1 µg t-cinnamic acid
formed h-1 g-1fresh weight in case of Xa23-PbXo-4, Xa23-PbXo-7, Xa23-PbXo-8,
Xa23-PbXo-10 and Xa23-Sgr-1001 interaction respectively after 96 hours of
inoculation. The current study showed the possible role of these three antioxidant
enzymes in imparting disease resistance in IRBB23 carrying Xa23 gene and suggests
that the disease intensity depends upon the level of expression of three defense related
enzymes in planta. The lesion length and pathogen population in the host also
correlated negatively with the level of expression of different defense related enzymes.
Keywords: Biochemical expression, X. oryzae pv. oryzae, Rice bacterial blight
The 6th International Conference on Bacterial Blight of Rice
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P05: Biocontrol Assessment of Actinomycetes and Bacteria Against Rice
Bacterial Blight
Tran Ha Anh, Tran Thi Kieu, Nguyen Duc Cuong and Nguyen Thi Phong Lan
Plant Protection Department, Cuu Long Delta Rice Research Institute, Vietnam
Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is one
of the most destructive diseases of rice. The objective of this biocontrol experiments
was to identify the capable of controlling rice BB disease using actinomycetes and
bacterial strains. The results showed that, the in vitro test of antagonist Pseudomonas
fluorescens against Xoo had identified five strains (Ps.HG-11, Ps.HG-82, Ps.HG- 44,
Ps.HG-35 and Ps.HG-17) out of 158 bacteria strains expressing highly growth
inhibition. In addition, they also showed proteolytic activity. About Actinomycetes
strains, three rhizospheric isolates (AC.R.22, AC.R.44, AC.R.157) and one
endophytic isolate (AC.E.28) were the most effective isolates against Xoo. In the net
house condition, three bacterial strains (Ps.HG-11, Ps.HG-82 and Ps.HG-44) were
identified to have high control efficacy against BLB disease, among of which, Ps.HG-
11 was the most effective strain. Spraying P. fluorescens at two days before and after
pathogen inoculation showed highest control ability of BLB disease. About
Actinomycetes strains, both rhizospheric and endophytic isolates gave the good
biocontrol against BLB disease at 7 and 14 DAS of biocontrol agents, the rhizospheric
isolate (AC.R.44) was found as the highest effective biocontrol against BLB disease.
These results suggest that the further investigations should survey more efficacy
biocontrol strains of actinomycetes and bacteria againt BLB in the field condition.
Keywords: Xanthomonas oryzae pv. oryzae, biocontrol, Pseudomonas fluorescens,
Actinomycetes
The 6th International Conference on Bacterial Blight of Rice
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P06: Evaluation of Rice Genetic Resource for Resistance to Xanthomonas
oryzae pv. oryzicola
Trung Nguyen Quoc, Hai Tong Van, Chau Nguyen Thi Cam, Hien Phan Thi
Faculty of Biotechnology, Vietnam National University of Agriculture
The bacterial leaf streak (BLS) in rice, caused by Xanthomonas oryzae pv. oryzicola
(Xoc), is a destructive bacterial disease, especially in autumn season. In 2018, Plant
Protection Department in Vietnam reported that 2.826 ha was infected with Xoc and
distributed mostly in northern part. This study was aimed to screen diverse germplasm
for BLS resistance in order to select potential genetic resource to identify novel
resistant gene for breeding.
We selected 113 chromosome segment substitution lines (CSSLs) from O. rufipogon
and japonica rice Asominori with genetic background of IR24 including 71 RufIL and
42 IAS lines respectively. Fifty local varieties and 5 IRBB lines carrying (Xa4, xa5,
Xa7, Xa10 and Xa21) were also tested for BLS resistance. Artificial inoculation with
2 Xoc isolate (TB4 and TN158) was carried out and measured 56horis length 10 days
after infection. CSSLs showed broad-spectrum resistance suggesting the presence of
resistance gene in O. rufipogon and Asominori variety. Highest resistance was
identified in local varieties with several accessions. Result of checking ability of XA
genes against Xoc isolates showed different reaction patterns in which xa5 had highest
resistant level.
The high resistant accessions were potential material for further gene discovery and
utilizing in breeding programs. Diverse genetic source of resistance could strengthen
Vietnamese cultivars collection against BLS in long-term.
Keywords: bacterial leaf streak, artificial inoculation, resistance, CSSLs, germplasm.
The 6th International Conference on Bacterial Blight of Rice
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P07: Transcriptional Responses to Type III Secretion System Inhibitor
Ortho-Coumaric Acid of Xanthomonas oryzae pv. oryzae
Fan SS1, Tian F1, Fang LW2, Yang C-H2, He CY1
1State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of
Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; 2Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee,
WI 53211, USA
Ortho-coumaric acid (OCA), a plant-derived phenolic compound was previously
identified as a type III secretion system (T3SS) inhibitor of the bacterial leaf blight
pathogen of rice Xanthomonas oryzae pv. oryzae (Xoo). However, the molecular
mechanisms underpinning the T3SS inhibition by OCA and the transcriptional
responses to the OCA treatments in Xoo remain to be elucidated. RNA-seq-based
transcriptomic analysis was conducted in this study to reveal changes in bacterial gene
expression in response to 30 min, 1 h, 3 h, and 6 h of OCA treatment. Results showed
that OCA significantly inhibited the T3SS gene expression, and membrane proteins in
the functional category of the cellular process appeared to be the predominant group
after 30 min of OCA treatment. More differentially expressed genes (DEGs) gathered
in the functional category of the biological process over time. Analysis of common
DEGs at all time points identified the core elements in Xoo during the response to
OCA treatment. Notably, a multidrug transporter gene cluster that encodes a MarR-
family transcriptional regulator (mdtX1), a multidrug RND transporter (mdtX2), a
multidrug transporter (mdtX3), and a MFS transporter (mdtX4) was significantly up-
regulated by OCA treatment at all time points. Genetic analysis demonstrated that
deletion of mdtX1 in Xoo affected the OCA-induced expression of mdtX2-4, but not
the OCA-inhibited T3SS expression. Therefore, our study revealed the landscape of
bacterial responses to OCA at the whole-genome transcription level, and identified an
OCA-responsive multidrug transporter cluster, which might not be specifically
involved in the T3SS inhibition in Xoo.
Keywords: Xanthomonas oryzae pv. oryzae; type III secretion system; phenolic
compound; transcription; multidrug transporter
The 6th International Conference on Bacterial Blight of Rice
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P08: The EdpX1-Clpxoo Circuit Mediates Cyclic Di-GMP Signaling and
Regulates Type III Secretion System and Virulence in Xanthomonas oryzae
pv. oryzae
Xue DR1, Tian F.1, Li B., 1 Yang C-H2, He CY1
1State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of
Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; 2Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee,
WI 53211, USA
C-di-GMP, a bacterial second messenger is synthesized by diguanylate cyclases
(DGCs, with GGDEF domains), degraded by specific phosphodiesterases (PDEs, with
EAL of HD-GYP domains) and sensed by a wide variety of c-di-GMP binding
effectors that control diverse targets, thus controlling bacterial virulence,
exopolysaccharide (EPS) production and biofilm formation. EdpX1, a confirmed PDE
was shown to regulate positively the virulence, EPS production and biofilm formation
of Xanthomonas oryzae pv. oryzae. Clpxoo, a c-di-GMP binding effector and a global
transcriptional regulator (with cNMP-/HTH DNA-binding domains) regulated similar
phenotypes mentioned above. Whether Clpxoo works with EdpX1 in same c-di-GMP
signaling pathway is further investigated in this study. ∆edpX1 not only showed
reduced induction of water soaking (WS) in rice and hypersensitive response (HR) in
tobacco, but also attenuated translocation of two T3SS effectors PXO_03702 and
PXO_04172, indicating EdpX1 regulation of T3SS functions. EdpX1 affected EPS
production and the gum gene transcription. Notably, negative regulation by EdpX1 of
transcription of clpxoo was observed. No significant change in intracellular c-di-GMP
level in wildtype and Δclpxoo existed. Remarkable reduction of c-di-GMP
concentration in ΔedpX1Δclpxoo and significant increase in ΔedpX1(clpxoo)
compared with ΔedpX1 was also found. Moreover, there was no significant difference
in c-di-GMP level in Δclpxoo and Δclpxoo(edpX1). These findings indicate that
Clpxoo significantly affects intracellular c-di-GMP levels, which might be
counteracted by EdpX1. EPS production of ΔedpX1(clpxoo) but not Δclpxoo(edpX1)
restored to the wildtype level, suggesting that Clpxoo acts downstream of EdpX1 in
regulating EPS production. Like EdpX1, Clpxoo positively regulated the induction of
WS in rice and HR in tobacco, suggesting Clpxoo regulation of T3SS functions.
Importantly, a subset of genes directly regulated by Clpxoo were identified through
chromatin immunoprecipitation sequencing (ChIP-seq), and validated by
electrophoretic mobility shift assay (EMSA) and qRT-PCR analysis, including those
encoding DGCs (GdpX5-6) and transcriptional regulators. Altogether, this study
demonstrates that Clpxoo functions in EdpX1-mediated signaling pathway in a c-di-
GMP dependent manner.
Keywords: Xanthomonas oryzae pv. oryzae, c-di-GMP signaling, receptor, T3SS,
regulation
The 6th International Conference on Bacterial Blight of Rice
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P09: Role of a Host-Induced Arginase of Xanthomonas Oryzae pv. Oryzae in
Promoting Virulence on Rice
Zhang Yuqiang, Wu Guichun, Zhao Yancun, Liu Fengquan
Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences,
Nanjing 210014, China
The plant bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial
blight of rice, which is one of the most destructive diseases prevalent in Asia and parts
of Africa. Our preliminary study has discovered a host-induced protein
PXO_RS22625 in the Xoo-rice system using the proteomic method. However, little is
known about the molecular mechanism of host-induced expression of PXO_RS22625
and its regulation of virulence of Xoo. Here, we show that the deletion of the
PXO_RS22625 gene caused a significant decrease in the virulence of Xoo in the
susceptible rice cultivar IR24. Bioinformatics analysis demonstrated that
PXO_RS22625 encodes the RocF protein, which is an arginase that converts arginine
into ornithine and urea. Quantitative real-time PCR (qRT-PCR) and Western blot
assays revealed that expression of the rocF gene was significantly induced by rice and
arginine. The rocF gene deletion mutant strain showed elevated sensitivity to
hydrogen peroxide (H2O2), reduced the production of extracellular polysaccharide
(EPS) and reduced biofilm formation, all of which are important determinants for the
full virulence of Xoo, compared to those of the wild-type strain. Taken together, the
results of this study revealed a unique mechanism by which a bacterial arginase is
required for the full virulence of Xoo on rice because of its contribution to tolerance to
reactive oxygen species, production of EPS, and biofilm formation.
Key words: Xanthomonas oryzae pv. oryzae, Arginase, Virulence, Biofilm
The 6th International Conference on Bacterial Blight of Rice
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P10: TalC, a Conserved Virulence Effector of African X. oryzae pv. oryzae
Strains Targeting OsSWEET14 Activates Bidirectional Transcription of a
Second Rice Locus.
Doucouré H.*1, Auguy F.*2, Blanvillain-Baufumé S.2, Fabre S.2, Thomas E.2,
Dambreville F.2, Sciallano C.2, Szurek B.2, Koita O.1, Verdier V.2, Cunnac S.2
1Laboratoire de Biologie Moléculaire Appliquée, Université des Sciences Techniques
et Technologiques de Bamako, Faculté des Sciences et Techniques (FST), Bamako,
Mali 2IRD,CIRAD, Univ Montpellier, IPME, Montpellier, France
Xanthomonas oryzae pv. oryzae (Xoo) strains that cause Bacterial Leaf Blight (BLB)
in sub-Saharan regions of Africa, limit domestic rice (Oryza sativa) production and
require breeding more resistant varieties. Type III secretion substrates of the
Transcription Activator-Like Effector (TALE) family reach the host cell nucleus
where they activate gene transcription to promote leaf colonization by binding to
specific DNA sequences termed Effector Binding Elements (EBE). Xoo major TALEs
universally target susceptibility genes of the SWEET transporter family. In nature,
polymorphism in the sequence of EBEs upstream of OsSWEET genes creates TALE-
unresponsive alleles and resistance to BLB. Similar mutations have been artificially
introduced in the OsSWEET14 susceptibility gene promoter with genome editing and
conferred resistance to some Asian Xoo strains. African Xoo strains rely primarily on
the major TALE TalC which is ubiquitous in the genomes of this group and which
also targets OsSWEET14. Recent work has established that although the virulence of a
60hor mutant strain is severely impaired, abrogating OsSWEET14 induction with
genome editing did not confer resistance to African Xoo.
To address this contradiction, we postulated the existence of a TalC target
susceptibility gene redundant with OsSWEET14. Bioinformatics analysis identified a
rice locus named ATAC (Alternative TalC target) composed of two transcripts that
were shown to be bidirectionally upregulated in a TalC-dependant but OsSWEET14
induction-independent fashion. Gain of function approaches with designer TALEs
inducing ATAC sequences did not complement the virulence of a Xoo strain incapable
of activating a SWEET gene. Furthermore, while editing the TalC EBE at the ATAC
loci compromised TalC-mediated induction, multiplex edited lines with mutations at
the OsSWEET14 and the ATAC loci remained essentially susceptible to African Xoo
strains. Collectively these results demonstrate that during Xoo infection, TalC not only
induces OsSWEET14 but also concomitantly triggers bidirectional transcription at the
ATAC locus, presumably by direct recognition of a cognate EBE. Genetic approaches
failed to unequivocally evidence a role of ATAC genes in BLB susceptibility. This
may indicate that ATAC is an off-target of TalC or that explaining its relevance in the
disease process will require disentangling the contribution of TalC and clade III
OsSWEET genes to the virulence of African Xoo strains.
The 6th International Conference on Bacterial Blight of Rice
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P11: Xanthomonas oryzae pv. oryzae Employs a Host-induced Metabolic
Enzyme for Modulating its Pathogenicity
Yancun Zhao, Guichun Wu, Fengquan Liu
Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences,
Nanjing 210014, China
Xanthomonas oryzae pv. oryzae (Xoo) that causes the bacterial blight of rice is an
important pathogenic bacterium in the world’s rice production. During Xoo-rice
interaction, a growing number of high-throughput transcriptome and proteome
analysis have discovered the induced expressions of some important virulence-related
genes. The functions of these genes are closely associated with the survival,
proliferation and synthesis of virulence factors of Xoo in rice. Here, We demonstrated
that xanA was a virulence gene whose expression could be induced in both the in vitro
Xoo-rice system and inside the rice using Western Blot, quantitative fluorescence
assay, and GUS staining. Through the prokaryotic expression and biochemical
function analysis of XanA, it was found that XanA possessed glucose phosphomutase
activity in Xoo, and regulated the dynamic balance between glucose-1-phosphate and
glucose-6-phosphate. The combined use of genomic, transcriptomic and proteomic
techniques and virulence phenotype analysis indicated that xanA regulated virulence
by influencing the utilization of carbon source by Xoo, EPS synthesis, biofilm
synthesis, flagellar motion and chemotaxis. FruA, CheY and FlhF might be the
important mediators of the above regulatory mechanism. In addition, bacterial one-
hybrid experiment and gene expression analysis revealed that carbon sources such as
xylose and galactose widely present in rice induced the expression of xanA to varying
degrees. The gene xanA itself received regulation by the AraC family transcriptional
regulators such as PXO_06036. Taken together, the AraC family transcriptional
regulators may play important roles in virulence regulation by xanA and host-induced
expression of xanA in rice.
Keywords: Xanthomonas oryzae pv. oryzae, Pathogenicity, xanA, Virulence factor
The 6th International Conference on Bacterial Blight of Rice
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P12: Engineering Broad-Spectrum Bacterial Blight Resistance by
Disrupting Variable TALE-Binding Elements of Multiple Susceptible
Genes in Rice
Xu Zhengyin1, Wang Sai1, Yang Yangyang1, Liu Longyu1, Li Ziyang1, Li Ying1, Ma
Wenxiu1, Zhu Bo1,2, Zou Lifang1,2 and Chen Gongyou1,2
1School of Agriculture and Biology, Shanghai Jiao Tong University/Key Laboratory of
Urban Agriculture by Ministry of Agriculture of China, Shanghai 200240, China; 2State Key Laboratory of Microbial Metabolism, School of Life Sciences &
Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
Xanthomonas oryzae pv. oryzae (Xoo), causal agent of bacterial blight of rice, recruits
transcription activator-like effectors (TALEs) to induce expression of OsSWEET
genes, which function in sugar transport and disease susceptibility. To engineer broad-
spectrum bacterial blight resistance, we used CRISPR/Cas9-mediated gene editing to
disrupt the TALE-binding elements (EBEs) of two S genes, OsSWEET11 and
OsSWEET14, in rice cv. Kitaake, which harbors recessive resistance allele
Xa25/OsSWEET13. The engineered rice line MS14K exhibited broad-spectrum
resistance to most Xoo strains with a few exceptions, suggesting that the compatible
strains may contain new TALEs. We identified Tal5LN18 and Tal7PXO61, PthXo2-like
TALE effectors, as major virulence factors in the compatible Xoo strains LN18 and
PXO61, respectively, and found that Xoo encodes at least five types of PthXo2-like
effectors. Given that PthXo2/PthXo2.1 target OsSWEET13 for transcriptional
activation, the genomes of 3000 rice varieties were analyzed for EBE variations in
OsSWEET13 promoters, and ten Xa25-like haplotypes were identified. Tal5LN18 and
Tal7PXO61, were shown to bind slightly different EBE sequences in the OsSWEET13
promoter and activated its expression. CRISPR/Cas9 technology was then used to
generate InDels in the EBE of the OsSWEET13 promoter in the mutant MS14K. This
resulted in the creation of new germplasm with three edited OsSWEET EBEs and
broad-spectrum resistance against all Xoo strains tested. Our findings illustrate how to
disarm TALE-S co-evolved loci to generate broad-spectrum resistance through the
loss of effector-triggered susceptibility.
Key words: Xanthomonas oryzae pv. oryzae, TALE, susceptible gene, ETS, RLS
The 6th International Conference on Bacterial Blight of Rice
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P13: Role of an Orphan Response Regulator in Promoting Virulence of
Xanthomonas oryzae pv. oryzae on Rice
Pandey A
Microbial Technology Division, CSIR-Central Institute of Medicinal and Aromatic
Plants, Lucknow- 226015, India
Two component systems (TCSs) are one of the most prevalent ways by which bacteria
sense, respond, and adapt to various changes in their environment. We are using Rice-
Xanthomonas oryzae pv. oryzae (Xoo; the causal agent of rice disease called bacterial
blight) pathosystem to understand the role of TCSs in plant-microbe interaction.
Genome sequence analysis revealed that Xoo strains are equipped with large
repertoire of TCSs. TCS constitute a signal transduction mechanism which is basically
formed by two proteins: a membrane bound histidine kinase sensor and a cytoplasmic
response regulator. Sensor histidine kinase responds to an environmental change or
stimulus by phosphorylating a cognate response regulator which triggers changes in
cellular physiology or gene expression in order to enhance adaptability. A system
level mutagenesis in an Indian Xoo strain BXO1 led to identification of several
virulence genes encoding for response regulators. Here, work will be presented
indicating importance for an orphan response regulator (encoded by BXO1_05645
gene) for Xoo virulence on rice. This response regulator contains the CheY-like
receiver domain and is required for in planta growth as well as migration, suppression
of host defense response, induction of non-host resistance, optimum expression of
type 3 secretion system, EPS production, motility, biofilm formation and survival
under specific stress conditions.
The 6th International Conference on Bacterial Blight of Rice
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P14: Biosynthesis of Coenzyme Q in the Phytopathogen Xanthomonas via a
Yeast-Like Pathway
Zhou Lian, Wang Xing-Yu, He Ya-Wen
State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of
Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai
Jiao Tong University, Shanghai 200240, China
Coenzyme Q (CoQ) is a lipid-soluble, membrane component found in organisms ranging
from bacteria to mammals. The biosynthesis of CoQ has been intensively studied in E. coli
where twelve genes, ubiABCDEFGHIJKX, are involved. The phytopathogens Xanthomonas
campestris pv. campestris (Xcc) and X. oryzae pv. oryzae (Xoo) produce CoQ8 as the major
ubiquinone. Interestingly, both Xcc and Xoo contain no homologues of the E. coli
64horismite lyase-encoding ubiC. They instead contain the gene xanB2 (Xcc4014 in Xcc
and PXO_3739 in Xoo, respectively) which encodes a novel bifunctional chorismatase
needed for the biosynthesis of both 4-HBA and 3-HBA. The XanB2-dependent 4-HBA is
required for CoQ8 biosynthesis. The other genes involved in Xcc CoQ8 biosynthetic
pathway remain to be elucidated. In this study, we first investigated the putative genes for
CoQ8 biosynthesis in the phytopathogen Xcc using a combination of bioinformatics, genetic
and biochemical methods. We showed that Xc_0489 (coq7Xc) encodes a di-iron carboxylate
monooxygenase filling the E. coli UbiF role for hydroxylation at C-6 of the aromatic ring.
Xc_0233 (ubiJXc) encodes a novel protein with an E. coli UbiJ-like domain organization and
is required for CoQ8 biosynthesis. The Xcc decarboxylase gene remains unidentified.
Further functional analysis showed that ubiB and ubiK homologues ubiBXc and ubiKXc are
required for CoQ8 biosynthesis in Xcc. Deletion of ubiJXc, ubiBXc and ubiKXc led to the
accumulation of an intermediate, 3-octaprenyl-4-hydroxybenzoic acid (OHB). UbiKXc
interacts with UbiJXc and UbiBXc to form a regulatory complex. Deletion analyses of these
CoQ8 biosynthetic genes indicated that they are important for virulence in Chinese radish.
These results suggest that the Xcc CoQ8 biosynthetic reactions and regulatory mechanisms
are divergent from those of E. coli. The variations provide an opportunity for the design of
highly specific inhibitors for the prevention of infection by the phytopathogen Xcc.
Keywords: Xanthomonas, Coenzyme Q, biosynthetic pathway.
The 6th International Conference on Bacterial Blight of Rice
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P15: Biosynthesis of the Yellow Pigments Xanthomonadin Involves an ATP-
dependent 3-HBA: ACP Ligase and an Unusual Type II Polyketide Synthesis
Pathway
Cao Xue-Qiang, Zhou Lian, He Ya-Wen
State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of
Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai
Jiao Tong University, Shanghai 200240, China
The genus Xanthomonas represents one of the most ubiquitous groups of plant-associated
bacterial pathogens. A characteristic feature of the genus Xanthomonas is the production of
yellow, membrane-bound pigments called xanthomonadins. Xanthomonadins play an
important role in maintaining the ecological fitness of Xanthomonas species by protecting
bacterial cells against photooxidative and peroxidative stress. A pig cluster is responsible for
xanthomonadin biosynthesis. Previously, Xcc4014 of the cluster was characterized as a
bifunctional chorismatase that produces 3-hydroxybenzoic acid and 4-HBA in X. campestris
pv. campestris (Xcc)(Zhou et al., Molecular Microbiology. 2013: 87: 80-93). This study
further characterized the roles of several other genes within the pig cluster. (1) Deletion
analysis identified a total of eleven genes to be essential for xanthomonadin biosynthesis.
Biochemical and bioinformatics analysis suggests that xanthomonadins are synthesized via
an unusual type II-polyketide synthesis pathway. Heterologous expression of the pig cluster
in Pseudomonas aeruginosa resulted in the synthesis of chlorinated xanthomonadin-like
pigments. These results further confirmed the role of pig cluster in xanthomonadin
biosynthesis. (2) We demonstrated that xanC encodes an acyl carrier protein (ACP) while
xanA2 encodes a bifunctional ATP-dependent 3-HBA:ACP ligase. Both of them act together
to catalyze the formation of 3-HBA-S-ACP from 3-HBA to initiate xanthomonadin
biosynthesis. (3) Finally, we showed that xanH encodes a FabG-like enzyme and xanK
encodes a novel glycosyltransferase. Both xanH and xanK are not only required for
xanthomonadin biosynthesis, but also required for the balanced biosynthesis of extracellular
polysaccharides and DSF-family quorum sensing signals. Accordingly, we propose a
schematic model that describes xanthomonadin biosynthetic pathway. These findings
provide us with a better understanding of xanthomonadin biosynthetic mechanisms and
directly demonstrate the presence of extensive cross-talk among xanthomonadin
biosynthetic pathways and other metabolic pathways.
Keywords: Xanthomonas, yellow pigments, type II polyketide synthesis pathway.
The 6th International Conference on Bacterial Blight of Rice
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P16: Application of Genome Editing Technology for Improving the
Bacterial Leaf Blight Disease Resistance of Vietnamese Important Rice
Cultivars Bacthom 7 and TBR225
Cao Le Quyen1, Vu Hoai Sam2, Nguyen Thanh Ha1, Phung Thi Thu Huong1, Pham
Thu Hang1, Nguyen Van Cuu1, Nguyen Thi Thu Ha1, Pham Thi Van1, Vu Mai Ha1,
Nguyen Duy Phuong1, Sebastien Cunnac3, Pham Xuan Hoi1
1Agricultural Genetics Institute, Hanoi, Vietnam 2National Institute of Medicinal Materials, Hanoi, Vietnam 3UMR Interactions Plantes Microorganismes Environment (IPME), IRD-CIRAD-
Universite, Montpellier, France,
Xanthomonas oryzae pv. oryzae (Xoo) causes serious bacterial leaf blight (BLB)
disease to many Vietnamese important rice cultivars, including Bacthom 7 and
TBR225. Recently, marker-assisted selection (MAS) has been successfully used to
developed BLB resistant rice cultivars in Vietnam. However, the practical use of
MAS in rice breeding programs is limited for various reasons, including genetic
background interactions of identified quantitative trait loci (QTL), large genotype-by-
environment interaction effects. In this project, genome editing technology is firstly
used to improve the BLB resistance of popular rice variety Bacthom 7 and TBR225.
The high-efficient Bacthom 7 and TBR225 gene transformation protocols were
developed for editing target genes involved in the infection of Vietnamese Xoo strains
in these varieties. Nearly 300 Xoo isolates were collected from 22 provinces within
recent 6 years in Vietnam and identified the virulence on Bacthom 7 and TBR225
varieties. Several isolates were demonstrated that they were virulent on Kitakee wide-
type line but not on SWEET14 mutant line. Additionally, the expression of SWEET14
and SWEET11 in Bacthom 7 rice plants were induced by the infection of some of
these isolates in RT-PCR experiments showed the particular involvement of
SWEET14 and SWEET11 genes to BLB disease in Bacthom 7. On the first stage of the
project, some Bacthom 7 T0 transgenic lines containing a mutation at well-known Tal5
and/or TalC EBE(s) on the promoter region of SWEET14 gene were successfully
generated and grown in greenhouse. On next stages, phenotype and genotype of T1
and T2 SWEET14-edited lines will be investigated to confirm the role of SWEET14
gene in Xoo infection in Bacthom 7 rice variety. The transcription activator-like
(TAL) effector genes of some representative Xoo strains will be sequenced to
identified other target effector binding elements (EBEs) on the promoter of
susceptible genes for editing by CRISPR/CAS9. The main goal of the project is to
generate improved Bacthom 7 and TBR225 varieties with a broad-spectrum resistance
against Vietnam Xoo strains.
Keywords: Bacthom 7, genome editing, SWEET11, SWEET14, TBR225
The 6th International Conference on Bacterial Blight of Rice
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P17: Ascent of CRISPR-Cas in the Macrocosm of Genome Engineering:
Application in Photophilic Rice
Prasanta K Dash*, Soumydeep Mukherjee, Nagendra K Singh
ICAR- National Institute of Plant Biotechnology, PUSA campus, New Delhi, India
Manipulation of genome in post-genomic era has been revolutionized by advent of
CRISPR-Cas. Amongst the genome manipulation methodologies such as ZFN,
meganucleases and TALEN that fall short of reproducible statistical significance have
been replaced by cost effective, precise and reproducible CRISPR technology.
CRISPR is the RNA integrant of a ribonucleo-protein complex that guides Cas, the
proteinaceous molecular scissor to cleave target site proximal to the conserved PAM
sequence in the genome while CRISPR-RNA engenders editing. Alleviation of
deleterious effects of biotic and abiotic stresses in plants and animals is an important
use of targeted genome editing by CRISPR. Cardinally important crop such as rice
exposed to harsh biotic and abiotic stress produce sub-optimal quality and quantity of
yield. Amongst many, pathogenic leaf blight, is a major challenge to ideal growth and
yield of rice. Nonetheless, diverse applications in plants including multiplex gene
mutation, gene replacement, and transcriptional control makes CRISPR a superior
alternative to conventional breeding methods. Loss-of-function of susceptible genes
by CRISPR mediated knockouts have earlier been utilized to generate plants tolerant
to herbicide, and endemic bacterial blight. Here, we scale the remarkable success of
CRISPR technology, its canonical role and promises it offers to offset the biotic
stresses and restoration of parity/ productivity in economically important photophilic
staple food rice.
The 6th International Conference on Bacterial Blight of Rice
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ICBB06 List of Participants
CHINA
Dr. Bo Zhu
School of Agriculture and Biology
Shanghai Jiao Tong University
800 Dongchuan RD. Minhang District
Shanghai, China
Email: bzhu1981@sjtu.edu.cn
Dr. Chao Yu
Institute of Plant Protection, Chinese
Academy of Agricultural Sciences, Beijing
100193, China
Email: yudoxichao@163.com
Dr. Fengquan Liu
Institute of Plant Protection, Jiangsu
Academy of Agricultural Sciences,
Nanjing 210014, China
Email: fqliu20011@sina.com
Dr. Fenghuan Yang
Institute of Plant Protection, Chinese
Academy of Agricultural Sciences, Beijing
100193, China
Email: fhyang1982@163.com
Dr. He Ya-Wen
School of Life Sciences and Biotechnology
Shanghai Jiao Tong University
800 Dongchuan RD. Minhang District
Shanghai, China
Email: yawenhe@sjtu.edu.cn
Dr. Huamin Chen
Institute of Plant Protection, Chinese
Academy of Agricultural Sciences, Beijing
100193, China
Email: chenhuamin@caas.cn
Dr. Lifang Zou
School of Agriculture and Biology
Shanghai Jiao Tong University,
800 Dongchuan RD. Minhang District
Shanghai, China
Email: zoulifang202018@sjtu.edu.cn
Dr. Zhengyin Xu
School of Agriculture and Biology
Shanghai Jiao Tong University,
800 Dongchuan RD. Minhang District
Shanghai, China
Email: xuzy2015@sjtu.edu.cn
Dr. Yancun Zhao
Institute of Plant Protection, Jiangsu
Academy of Agricultural Sciences,
Nanjing 210014, China
Email: zhaoyc27@126.com
FRANCE
Dr. Mathilde Hutin
UMR IPME, IRD-CIRAD-Université
Montpellier, Montpellier, France
Email: mathildehutin1@gmail.com
Dr. Sebastian Cunnac
IRD, CIRAD, Université Montpellier, IPME,
Montpellier, France
Email: Sebastien.Cunnac@ird.fr
The 6th International Conference on Bacterial Blight of Rice
69
Dr. Valerie VERDIER
Institut de Recherche pour le Développement
911 av Agropolis, Montpellier, 34000, France
Email: valerie.verdier@ird.fr
GERMANY
Dr. Sarah Schmidt
Heinrich Heine University
Düsseldorf, Germany
Email: Sarah.Schmidt.2@hhu.de
Dr. Wolf Frommer
Heinrich Heine University, Düsseldorf,
Germany
Email: frommew@hhu.de
INDIA
Dr. Deo Mishra
Bayer BioScience, Plot No. 13, Software
Layout, Madhapur, Hyderabad-500081
Email: deo.mishra@bayer.com
Dr. Kalyan Mondal
Division of Plant Pathology, ICAR-Indian
Agricultural Research Institute, New Delhi
110012
Email: mondal_kk@rediffmail.com
Dr. Jagjeet Singh Lore
Department of Plant Pathology, Department
of Plant Breeding and Genetics, Punjab
Agricultural University, Ludhiana, Punjab -
141 004
Email: jagjeetsingh-pbg@pau.edu
Dr. Gurjit Singh Mangat
Department of Plant Breeding and Genetics
Punjab Agricultural University, Ludhiana-
141004, Punjab, India
Email: ishwinder-pp@pau.edu
Dr. Reeny Mary Zacharia
Rice Research Station, Moncompu,
Alappuzha, Kerala
zacharia.reeny485@gmail.com
Dr. Sachin Khedekar
Advanta India Limited
Hyderabad, Telangana
Email: sachin.khedekar@advantaseeds.com
INDONESIA
Dr. Hardian Susilo Addy
Department of Plant Protection. Faculty of
Agriculture, University of Jember
Email: hsaddy.faperta@unej.ac.id
Ms. Rejeki Desi
Graduate School of Biotechnology,
University of Jember
Email: desirejeki12@gmail.com
INTERNATIONAL RICE RESEARCH INSTITUTE (IRRI)
Dr. Ricardo Oliva
International Rice Research Institute, Los
Banos, Laguna 4031 Philippines
Email: R.Oliva@irri.org
Dr. Christian Paolo Balahadia
International Rice Research Institute, Los
Banos, Laguna 4031 Philippines
Email: c.balahadia@irri.org
The 6th International Conference on Bacterial Blight of Rice
70
Dr. Jonas Padilla
International Rice Research Institute, Los
Banos, Laguna 4031 Philippines
Email: j.padilla@irri.org
Dr. Marian Hanna Nguyen
International Rice Research Institute, Los
Banos, Laguna 4031 Philippines
Email: m.nguyen@irri.org
JAPAN
KOREA
Dr. Seiji Tsuge
Kyoto Prefectural University, Kyoto, Japan
Email: s_tsuge@kpu.ac.jp
Dr. Lin-Woo Kang
Department of Biological Sciences, Konkuk
University, 120 Neungdong-ro, Gwangjin-gu,
Seoul 05029
Email: linwookang@gmail.com
MALAYSIA
SENEGAL
Mrs. Kogeethavani Ramachandran
Rice and Paddy Research Centre, Malaysian
Agriculture and Development Institute,
Selangor 43400
Email: kogeetha@mardi.gov.my
Dr. Hamidou Tall
Institut Sénégalais de Recherches Agricoles
(ISRA), Bel Air, Dakar Sénégal
Email: midoutalel@yahoo.fr
MALI
Dr. Hinda Doucoure
Laboratoire de Biologie Moléculaire
Appliquée, Université des Sciences
Techniques et Technologiques de Bamako,
Faculté des Sciences et Techniques (FST),
Bamako
Email: doucourehinda@yahoo.fr
THE UNITED STATES
Dr. Jan E. Leach
Colorado State University, Fort Collins,
CO, USA
Email: Jan.Leach@colostate.edu
Dr. Jonathan M. Jacobs
Department of Plant Pathology and Infectious
Disease Institute, Ohio State University,
Columbus, OH, USA
Email: jacobs.1080@osu.edu
Dr. Adam J. Bogdanove
Plant Pathology and Plant Microbe
Biology Section, School of Integrative
Plant Science, Cornell University, Ithaca,
NY USA Email: ajb7@cornell.edu
Dr. Alvaro L Perez-Quintero
Colorado State University, Fort Collins,
CO, USA Email: alperezqui@gmail.com
The 6th International Conference on Bacterial Blight of Rice
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Dr. Jillian Lang
Department of Bioagricultural Sciences
and Pest Management, Colorado State
University, Fort Collins, CO, USA
Jillian.Lang@colostate.edu
VIETNAM
Dr. Le Quoc Doanh
Vice Minister
Ministry of Agriculture and Rural
Development (MARD)
2 Ngoc Ha, Ba Dinh, Ha Noi, Vietnam
Dr. Nguyen Hong Son
President
Vietnam Academy of Agricultural Sciences
(VAAS), Thanh Tri, Ha Noi, Vietnam
Email: nguyenhongson1966@gmail.com
Dr. Nguyen Quang Tin
Department of Sciences, Technology and
Environment, MARD
No. 2 Ngoc Ha, Ba Dinh, Ha Noi,
Vietnam
Mr. Bui Quang Dang
Vietnam Academy of Agricultural Sciences
Thanh Tri, Ha Noi, Vietnam
Email: dangvrq@gmail.com
Mr. Nguyen Kim Chien
Department of Sciences, Technology and
Environment, MARD
No. 2 Ngoc Ha, Ba Dinh, Ha Noi, Vietnam
Dr. Bui Ba Bong
Former Vice Minister
Ministry of Agriculture and Rural
Development
No. 2 Ngoc Ha, Ba Dinh, Ha Noi, Vietnam
Mr. Nguyen Truong Giang
Department of Sciences, Technology and
Environment, MARD
No. 2 Ngoc Ha, Ba Dinh, Ha Noi,
Vietnam
Dr Pham Van Du
VNSAT Project Adviser, MARD
No. 2 Ngoc Ha, Ba Dinh, Ha Noi,
Vietnam
Mr. Le Thanh Tung
Department of Crop Production
MARD, Vietnam
Mr. Tran Van Dung
National Agricultural Extension Center
No 16, Thuy Khue, Tay Ho, Ha Noi,
Vietnam
Mr. Le Van Thiet
Department of Plant Protection
MARD, Vietnam
Mr. Le Quoc Cuong
Southern Regional Plant Protection
Center, Department of Plant Protection,
MARD, Vietnam
Mr. Mai Van Hao
Nha Ho Research Institute for Cotton and
Agriculture Development
Email: viennhaho.vaas@mard.gov.vn
Dr. Tran Tuan Tu
Ministry of Sciences and Technology
No. 113 Tran Duy Hung, Ha Noi, Vietnam
The 6th International Conference on Bacterial Blight of Rice
72
Dr. Tong Van Hai
Vietnam National University of
Agriculture, Vietnam
Email: haitv@astri.vn
Dr. Nguyen Huy Chung
Plant Protection Research Institute,
Vietnam
Email: hchungvasi@yahoo.com
Dr. Nguyen Quoc Trung
Vietnam National University of
Agriculture, Vietnam
Email: namdinhvn@yahoo.com
Dr. Pham Thien Thanh
Field Crops Research Institute, Vietnam
Email: thanhpttm@gmail.com
Dr. Nguyen Thi Thu Nga
Can Tho University, Vietnam
Email: nttnga@ctu.edu.vn
Dr. Vo Thi Minh Tuyen
Agricultural Genetics Research Institute,
Vietnam
Email: minhtuyenagi@gmail.com
Dr. Tran Vu Phen
Can Tho University, Vietnam
Email: tvphen@ctu.edu.vn
Dr. Cao Le Quyen
Agricultural Genetics
Research Institute, Vietnam
Email: lequyen19@gmail.com
Dr. Le Thanh Toan
Can Tho University, Vietnam
Email: lttoan@ctu.edu.vn
Dr. Nguyen Thi Minh Nguyet
Agricultural Genetics Research Institute,
Vietnam
Mr. Nguyen Van Huan
Bayer Vietnam Ltd.
Email: huan.nguyen1@bayer.com
Mr. Bui Van Kip
Bayer Vietnam Ltd.
Email: kip.bui@bayer.com
Mr. Nguyen Tran Anh Huan
Bayer Vietnam Ltd.
Email: huan.nguyen@bayer.com
Mr. Nguyen Hoang Son
Bayer Vietnam Ltd.
Email: son.nguyen@bayer.com
Mr. Dang Van Phuoc
Bayer Vietnam Ltd.
Email: phuoc.dang@bayer.com
Dr. Tran Ngoc Thach
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Nguyen Thuy Kieu Tien
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Huynh Van Nghiep
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Duong Hoang Son
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Hoang Dinh Dinh
Cuu Long Delta Rice Research
Dr. Tran Ngoc Tu
Cuu Long Delta Rice Research
The 6th International Conference on Bacterial Blight of Rice
73
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Tran Dinh Gioi
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Ho Le Thi
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Vu Tien Khang
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Nguyen Thi Phong Lan
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Doan Manh Tuong
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Trinh Quang Khuong
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Nguyen Duc Cuong
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Nguyen The Cuong
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Vo Thi Bich Chi
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Do Duc Tuyen
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Dang Minh Tam
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Tran Thi Thanh Xa
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Tran Vu Hai
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Nguyen Thanh Linh
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Bui Thanh Liem
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. La Cao Thang
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Nguyen Cao Quan Binh
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
Dr. Le Quang Long
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
The 6th International Conference on Bacterial Blight of Rice
74
district, Can Tho city, Vietnam district, Can Tho city, Vietnam
Dr Nguyen Huu Minh
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Vu Quynh
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms Tran Thi Anh Thu
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Dr. Pham Thi Be Tu
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Nguyen Le Van
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Tran Thi Thuy
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Mr. Nguyen Ngoc Hoang
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Tran Nhu Ngoc
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Dang Thi Tho
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms Mai Nguyet Lan
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Nguyen Thi Duong
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Nguyen Kim Thu
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Duong Vy Thao
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Mr. Nguyen Duc Thanh
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Mr. Nguyen Khoa Nam
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Mr. Nguyen Van Hieu
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms Vo Thi Thu Ngan
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Mr. Nguyen Khac Thang
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
The 6th International Conference on Bacterial Blight of Rice
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Ms Vo Thi Da Thao
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Nguyen Thi Xuan Mai
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Mr. Tran Phuoc Loc
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Tran Thi Kieu
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Tran Thi Nam Ly
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Tran Ha Anh
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Tran Thi Mong Quyen
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Nguyen Thi Thanh Thuy
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Mr. Do Tan Trung
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Nguyen Thi Kim Vang
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Nguyen Kim Vang
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
Ms. Tran Thi Be Hong
Cuu Long Delta Rice Research
Institute, Tan Thanh village, Thoi Lai
district, Can Tho city, Vietnam
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General Information
Conference venue
The 6th International conference on Bacterial Blight of Rice will be held at Muong
Thanh Luxury Can Tho, a five-star hotel in Can Tho city, Vietnam. The conference
hall “Tran Giang A Ballroom” is equipped with state-of-the-art LED screen visual and
audio facilities. The screen size is 400 cm x 900 cm, 16:9 viewing ratio.
Official language
The official language of the conference is English.
Visas
Visitors from certain countries with valid passports and tickets for their onward
journey do not require visas for a period time, depending on country. Please check this
website for information on visa exemption to Vietnam, https://lanhsuvietnam.gov.vn.
However, entry visas are required for restricted nationals, stateless persons, and those
from countries that have no diplomatic relations with the Philippines. Please contact
Vietnam Embassy/ Consulate nearest you to check the countries on the visa required
Climate
The climate is generally hot and humid. The time of the Conference coincides with the
season of rains and thunderstorms. It is advised that participants bring appropriate
clothing. In August, average weather temperature in Can Tho city, is 25-32°C/77-89°F.
Currency
Foreign currency may be exchanged to local currency (Vietnamese Dong) at the
airport and most major hotels. The exchange rate is relatively the same at the airport
and all major banking facilities in Can Tho. The Vietnam Dong is the currency used in
the whole country. The exchange rate as of August 2019: 23,200 to 23,250
Vietnamese dongs.
Electricity
In Vietnam, 220 volts is used, alternating at 60 cycles per second. Flat prongs plugs
are acceptable. Adapters can be obtained locally but it is better to bring your own.
Internet access
Internet access at Muong Thanh Can Tho Hotel is free. All other hotels have Internet
access.
ATMs and credit cards
ATMs are available in Muong Thanh Can Tho Hotel and in some public areas. All
major establishments accept American Express, Mastercard, and Visa. Expect a 3-5%
surcharge. In general, banks are open from Monday to Friday, 9:00 a.m.-3:00 p.m.
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Insurance
We recommend that all participants obtain personal travel and life insurance for their
trip.
Safety and Security Precautions
Although Can Tho City is friendly to visitors, travelers are advised to take the
necessary precautions. Do not walk alone in unpopulated streets after dark or before
dawn. Take a taxi to go to a restaurant or an entertainment place that is far from your
hotel, especially in the evenings. Try to walk-in a group and do not draw unnecessary
attention to yourself by wearing meeting badges, carrying large sums of money, or
wearing jewelry. Lock your cash and valuables in your hotel safe when you do not
need them.
Health Regulations
A certificate of vaccination against yellow fever is required for travelers coming from
infected areas. Otherwise, visitors are not required to take any vaccination.
Registration
The registration desk will open on 18 August 2019 (Sunday) from 2:00 to 7:00 p.m
and on 19 August from 7:30 to 8:30
Conference bags
Delegates, speakers, and other special guests will be given conference bags at the
registration area. Each bag contains the program, the abstract book, ID and some
materials from sponsors.
Dress code
Participants are advised to be in business attire during the conference. Casual clothing
may be worn during field visits.
Exhibition area
Exhibits will be displayed at the foyer and in the corridors near the conference hall
(Tran Giang A Ballroom). It will be open from 8:00a.m.to 5:00p.m.
Food and refreshments
Morning and afternoon snacks will be served at the Tran Giang A Ballroom. Buffet
Lunch will be set-up at the second floor of the hotel.
Green policy
We promote the green policy through the judicious use of available resources and
recycling of materials. Help us recycle plastics, glass, cans, and papers. Before you
leave the venue, please put your IDs and unused materials in drop boxes in designated
areas or surrender the items at the registration counter.
Mobile devices
It is highly recommended that mobile phones be put in silent mode throughout the
duration of the conference to avoid disrupting the proceedings.
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No smoking policy
Smoking in the conference area is strictly prohibited.
Speakers’ presentation
Speakers should submit their final presentation, saved in a USB flash drive, to the AV
technician at the speakers’ desk. All presentations should be in PowerPoint format.
For details please refer to “Guidelines for Speakers”.
Welcome Reception and Social Program
All participants are invited to attend the Gala Dinner which will be hosted by the
Local Organizer in the Cam Thi Giang Banquet Hall, the 3nd Floor of the Muong
Thanh Can Tho Hotel, on 19 August, from 6:00 to 8:00 p.m. Participants may take
this opportunity to catch-up with friends and build networks with colleagues from
different institutions, universities and the industry while learning from various
scientists/researchers through the Welcome reception. While having dinner, guests
will be entertained with national and traditional music plays and songs to have a feel
of the Vietnamese culture.
Speakers’ Information
All speakers are requested to follow the instructions below:
1. Please submit your PowerPoint presentation to the speakers’ desk located at the
left wing of the Tran Giang A Ballroom during registration. In case video films
are combined with the PowerPoint, please make sure to make a test-run in the
designated session hall at least 30 minutes before the start of the session (even
though you have already checked it in the Speakers’ Desk).
2. If you are willing to share your presentation with participants, please display your
email address on the last slide of the presentation.
3. Kindly be ready at least 15 minutes before your session to meet your session
chairperson and fellow speakers.
Please follow the instructions of the chairperson in charge.
Each invited speaker is given 20 minutes to present their lecture; an additional 5
minutes will be allocated for discussion after the presentation.
Important note for Macintosh users
To use Mac presentations on a PC-compatible computer, note that you need to prepare
it according to the instructions below before bringing it to the speakers’ desk:
- Use a common font, such as Arial, Times New Roman, Verdana, etc. Special fonts
might be changed to a default font on a PowerPoint-based PC.
- Insert pictures as JPG files (and not TIF, PNG, or PICT- these images will not be
visible on a PowerPoint-based PC).
- Use a common movie format, such as AVI, MPG, or WMV (MOV files from
QuickTime will not be visible on a PowerPoint-based PC). Instructions to Poster
Presenters:
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Poster presentations will be done at the Tran Giang A Ballroom foyer (see map).
The poster should fit the poster board- ~100 cm (width) x ~120 cm (height).
The poster must be shown in the properly designated board (consult the Secretariat for
board assignment).
Stand beside your poster for the whole duration of the presentation proper and
encourage your audience to engage in a discussion about your presentation. Follow
the instructions given by the chairperson.
Set up your poster on 18 August 1:00 at 5:00 p.m, or during registration time (before
8:30) of 19 August.
Dismantle your poster display on 20 August after 6:00 p.m.
The 6th International Conference on Bacterial Blight of Rice
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Venue Maps
The 4th Floor Plan of the Muong Thanh-Can Tho Hotel
The Conference Venue: Tran Giang A Ballroom
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The Ground Floor Plan of the Muong Thanh-Can Tho Hotel
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