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Gene Introgression from wild relatives to cultivated crops

ManjappaIII Ph. D Scholar

Dept. of Genetics and Plant Breeding UAS GKVK Bangalore

III Seminar on

WELCOME

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CONTENTWhat are crop wild relatives

Requirement for systematic CWR conservation

Pest and/or disease resistance

Increasing yield

Abiotic stress tolerance

CMS or fertility restorers for use in producing hybrids,

Improving quality traits of the crop

Herbicide resistance

Future priorities

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What are crop wild relatives ??..

Crop wild relatives (CWR), which include the progenitors and

wild/weedy relatives (primary gene pool) and distantly related taxa, having

potential for crop improvement (secondary and tertiary gene pools)

These are important but scarcely exploited component of the gene pool,

have been undeniably beneficial to modern agriculture, providing plant

breeders with a broad pool of potentially useful genetic resources.

Wild cousins of cultivated crops

Having novel factors for wider adaptability, tolerance/ resistance to

disease, insect-pests, yield, quality attributes, sources of male sterility and

abiotic traits.

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CWR contain a wealth of genetically important traits due to

their adaptation to a diverse range of habitats and the fact that

they have not passed through the genetic bottlenecks of

domestication (Vollbrecht and Sigmon, 2005; FAO, 2008).

Global climate change leads to dynamic changes in biotic and

abiotic stresses affect crop yield. So use of CWR are an obvious

target to aid crop improvement and food security.

Despite its imp. only 2– 10% of global gene bank collections

comprise CWR accessions and that these samples only represent

a very small proportion of global CWR species (Maxted and Kell,

2009).

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166 species of native cultivated plants and over 320 wild relatives (Zeven and de Wet, 1982)

How rich we are in CWR ?

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• CWR were used in crop improvement in sugar cane in the first half of the 20th century• Their utility was recognized in breeding programs of major

crops in the 1940s and 1950s (Plucknett et al. 1987)•wild gene use in crop improvement gained in prominence by

the 1970s and 1980s with their use being investigated in an increasing wide range of crops (Hoyt 1988)Yield and quality contributions from CWR to US-grown or

imported crops amounted to over $340 million a year (Prescott-Allen and Prescott-Allen 1986).

• Recently significant advances have been in made in molecular technologies and hybridization procedures available for breeding and cultivar development that allow for the incorporation of more distantly-related taxa

Time line of CWR use

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Requirement for systematic CWR conservation has been recognized by major bodies • FAO of the UN in the International Treaty on PGR for Food and

agriculture• CBD: CWR conservation as a global priority• The Global Strategy for Plant Conservation 2011–2020; states in

Target 9 that ‘‘70 % of the genetic diversity of crops including their wild relatives and other socio-economically valuable plant species [should be] conserved’’,• CBD Strategic Plan; Target 13 called for ‘‘By 2020, the status of crop

and livestock genetic diversity in agricultural ecosystems and of wild relatives [will have] been improved’’.• Global Crop Diversity Trust (GCDT, 2011) launched the project

‘‘Adapting agriculture to climate change: collecting, protecting and preparing crop wild relatives’’• Objectives: identifying global priority CWR, developing and

implementing an ex situ conservation action plan for priority species, and promoting the use of the conserved diversity in crop improvement programmes.

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http://www.cwrdiversity.org/checklist/

The inventory contains 1667 priority CWR taxa in 173 crop complexes, 37 families, 108 genera, 1392 species and 299 sub-specific taxa.Annotated with key ancillary data (regional and national occurrence, seed storage behaviour and herbaria housing major collections of the CWR).

Led by the Global Crop Diversity Trust and the Millennium Seed Bank of the Royal Botanic Gardens Kew, UK

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First annotated list of priority CWR of the world’s most important human and animal food crops

CWR prioritization based on 3 criteria1. Relative socio-economical

importance of the related crop2. Potential use for crop improvement3. Threatened status

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Number of priority CWR per world region

Genera with the most CWR are Solanum (124), Coffea (116), Prunus (102), Ficus (59) and Ribes (53)

Families with most CWR Leguminosae (253), Rosaceae (194), Poaceae (150), Solanaceae (131) Rubiaceae (116)

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Number of priority CWR per Vavilov Centre of Diversity

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Most Breeding use genus: Prunus (68), in grafting as rootstocks Solanum (32) includes multiple crops

Most breeding used traits: Disease resistance (240) Graft stock (170) Pest resistance (103)

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Inventory was used for global ecogeographic studies of the barley (Vincent et al., 2012) and grasspea (Shehadeh et al., 2013) gene pools, and for producing a national CWR inventory for the USA (Khoury et al., 2013).

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Gene introgression grouped according to their main functional category:

1. Pest and/or disease resistance

2. Abiotic stress tolerance

3. Increasing yield

4. CMS or fertility restorers for use in producing hybrids,

5. Improving quality traits of the crop.

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Use of crop wild relatives in the past 20 years in released cultivars of 13 crops of international importance

+ indicate number of wild relatives that have contributed beneficial traits to crop varieties- indicates wild relatives have not contributed beneficial traits in that category

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Pest and disease resistance

• Over 80% of the beneficial traits conferred by CWR genes• Prior to the mid-1980s, stories about wild genes preventing

devastation by pests and diseases were dominated by a handful of crop success stories

Oryza nivara S.D.Sharma & Shastry providing resistance to grassy stunt virus in rice

Stem and leaf rust resistance from Agropyron elongatum and Aegilops umbellulata, respectively, in wheat

Solanum demissum Lindl. for resistance to potato late blightMany tomato disease resistances introgressed from wild

species, mostly from Lycopersicon pimpinellifolium

(Prescott-Allen and Prescott-Allen 1986).

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Tomato• Charles Rick (1915-2002) who dedicated his life to discover, collect

and characterize exotic tomato germplasm• Today >83,000 tomato acc. are stored in seed banks worldwide,

ranking 1st among vegetable species collected (FAO 2010)• Main collections in world: Tomato Genetic Resources Center in

California (TGRC), USDA2 collection, World Vegetable Center in Taiwan

Many tomato disease resistances introgressed from wild species, mostly from Lycopersicon pimpinellifolium Mill• Since 1982 one per year with virtually all disease resistance genes

currently in commercial cultivars having been bred from wild genetic resources. (Rick and Chetelat 1995)• Over 40 resistance genes have been derived from Lycopersicon

peruvianum, L. cheesmanii, L. pennellii, and several other wild relatives (Rick and Chetelat 1995).

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• Bemisia tabaci is one of the most threatening pests in in Solanaceous crops such as tomato and pepper• Pesticide application is often not effective and hazardous• The exploitation of plant natural defenses that are present in wild

relatives of tomato, may offer a solution.• Screened 46 accessions of tomato and related wild species 3 methods of screening; (1)a free-choice test in a screen-house (Indonesia), (2) a no-choice test with clip-on cages in a greenhouse and (3) a leaf disc test in a climate-room • Antibiosis resulting in low adult survival was the major component

for resistance in tomato• Whitefly non-preference and resistance were associated with the

presence of type IV trichomes

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No ovipositionNot preferred

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S. galapagense PRI95004/PY-8027 is highly resistant to whitefly over time & is closely related to commercial tomato.

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• Stem or black rust (Puccinia graminis Pers. f. sp. tritici Eriks, et Henn.) and brown or leaf rust (caused by Puccinia triticina Eriks.) continue to be a serious threat in many wheat growing regions of the world.• Most introgression efforts involve the Aegilops spp. that had co-

evolved and grown alongside with cultivated wheat for the last several thousand years. • Leaf rust res. genes in D genome: Lr21, Lr22a, Lr32, Lr37, Lr39, Lr41,

Lr42 & Lr43• Lr34 (Ae. tauschii) is a minor/slow rusting gene which provides durable

resistance & presently used extensively in wheat improvement programme in India and worldwide• Objective: Evaluation of genetic diversity for stem and leaf rust

resistance in D genome species of wild relatives of wheat• Conducted in IARI regional center, Wellington (TN), primary natural

rust inoculum for central & peninsular India

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Response of accessions of D genome species of Aegilops to stem and leaf rust pathotypes

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Important genes in wheat found in related species

System-wide Genetic Resources Program (1996)

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The Genus Oryza : Broadening the Gene Pool of Rice—Exploitation of Diversity of the Wild Species Germplasm

Paul et al (2014) Genetics and Genomics of Rice

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Genus oryza: 12 representative species

IRRI Rice Gene Bank and The National Institute of Genetics’ Oryza base, combined, maintain >4,000 acc. of wild Oryza species and 1,500 cultivated O . glaberrima acc.

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Steps involved in gene transfer1. Search for useful genetic variability for target traits2. Production of hybrids and alien introgression lines ( AIL )3. Evaluation of introgression lines for transfer of target traits4. Molecular mapping of genes / QTLs

Rice varieties developed through wide hybridization

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Rice varieties developed through MAS carrying Xa21 gene from O. longistaminata & Bph18 from O. australiensis

Oryza minuta (101141 (2n=48, BBCC) x O. sativa cv IR31917-45-3-2 (2n=24, AA)Res. to blast and bacterial blight

BC1 X

F1 Xsterile

IR31917-45-3-2

IR31917-45-3-2

BC2F1

BC2F2

BC2F3

Chr. =44-47

Chr. =24-37

Res. to blast PO 6-6

13/16 Res. to blast

5 Res. to BB

10/21 Res. to BB race2, 3, 675-1 Chr. 24 78-1 Chr. 24

3R: 1S dominant Segregates same or closely linked gene(s) to races 2, 3, 5 & 6.

Screening for Blast Screening for BBEmbryo rescue

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During 1970s, epidemics of grassy stunt virus were reported in several countries.

Diseased plants produce no or only small panicles with deformed grains leads to severe yield losses or even total losses under epidemic conditions.

O. nivara (Acc 101508) crossed with IR8, IR20, IR24. Following three backcrosses, the gene for grassy stunt resistance was

transferred into cultivated germplasm. The first grassy stunt resistant varieties, IR28, IR29 and IR30 were

released for cultivation in 1974. Subsequently, IR32, IR34, IR36 were released. Since then, grassy stunt resistance gene has been incorporated into

numerous varieties developed at IRRI as well as by the national rice improvement programs.

Introgression of gene(s) for resistance to grassy stunt virus

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International Oryza Map Alignment Project (I-OMAP)

• I-OMAP has held five grand challenge meetings (Japan 2007, Korea 08, Philippines 09, Brazil 10, Taipei 11) in conjunction with the annual International Symposia on Rice Functional Genomics (ISRFG)• 3 primary focus areas of I-OMAP are to:1. Generate RefSeqs & Transcriptome data sets for all eight AA

genome species and a representative species of the nine other genome types

2. Generate map and phenotype advanced CSSL, RIL populations for the AA genome species for functional and breeding studies

3. Identify collections of naturally occurring populations of the wild Oryza species for diversity, conservation, population, and evolutionary analyses

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Oryza reference genome sequencing project as on oct. 2012

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Transfer of useful genes from wild species into cultivated rice through production of MAAL

recombination events

Wild segment introgressed

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Tagging of useful genes with DNA markers

Broad spectrum durable resistance

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Pi40 from O. australiensis conferred broad-spectrum durable resistance to blast isolates of different countries

O. australiensisSusceptible checkRecipient parent

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Four species of Meloidogyne (M. arenaria, M. javanica, M. hapla and M. incognita) attack groundnut in different parts of the world; first two species are widespread in India

In some areas of Gujarat, the losses to groundnut as high as 38–59% (Ali, 1997)

No practical nematode management options are available161 accessions of wild Arachis species within 7 botanical sections

(Arachis, Procumbentes, Erectoides, Heteranthae, Triseminatae, Extranevosae and Caulorrhizae), five interspecific groundnut derivatives, and 18 groundnut cultivars were obtained from ICRISAT.

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Potato late blight resistance

• Best resistance source for potato late blight are Solanum demissum and S. stoloniferum.• Currently 40% of the total area of the most popular potato cultivars

in US have S. demissum in their ancestry (National Potato Council 2003), • Along with these wild relatives, S. chacoense, S. acaule, S. vernei and

S. spegazzinii have provided resistance to several viruses and pests (Love 1999; Ross 1986).

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Resistance to hessian fly in wheat derive from goatgrass, Aegilops tauschii,

• During revolutionary war in America German auxiliary troops, called "Hessians," purportedly brought the pest to America in straw bedding• Major insect pest causing multimillion dollar crop loss• Resistance in wheat is critical to stopping the fly, during its maggot

stage, from feeding inside the plant, causing stems to buckle or stunting growth.• The new spring wheat lines, "Synthetic Hexaploid Wheat (SW)" 8, 34

and 39, all resist the Hessian fly Great Plains (GP) biotype. SW8 also resists the H13-virulent strain.

Hessian fly, 

Mayetiola destructor

(Suszkiw 2005).

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Wild Cicer species with resistance to various biotic and abiotic stresses

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Yield improvement

• In backcross progeny derived from crosses of two indica rice varieties (IR64 and IR55423-01) with O . glaberrima:

1. Two new QTLs for grain yield per plant ( ypp2 . 1 and ypp4 . 2 )

2. In IR55423-01 × O . glaberrima , 11 new QTLs for biomass identified

• Alleles associated with the yield-related traits, such as spikelet number, grain weight, and panicle length, were identified in this O . rufipogon accession using a BIL population derived from a cross with Zhenshan 97B

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Contd…

• Rice cultivar NSICRc112 released in the Philippines in 2002 from Oryza sativa and O. longistaminata (Brar 2005)

• Synthetic hexaploid (SH) wheats; cross between durum wheat and the wild relative Aegilops tauschii that has undergone artificial chromosome doubling (hexaploid)

• These lines are then back-crossed to elite bread wheat cultivars, to produce wheats with superior quality, disease resistance and yield.

• In 2003, ‘Chuanmai 42’, cross between an SH and a local cultivar, released in China, producing 20–35% higher yields (CIMMYT 2004).

• Pyramiding of three independent yield-promoting genomic regions introduced from Solanum pennellii, has led to hybrids with a 50% increased yield over a leading variety (Gur and Zamir 2004)

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Rice variety Dhanrasi, an example of improving yield potential and disease resistance by introgressing gene(s) from wild species (Oryza rufipogon)T. Ram et al., 2007. Curr. Sci., 92 (7): 987-992

BB, blast, tungro & yield QTLs

PHT, DF, PTN, PL, NOS, YLD

32 ILs + parents evaluated YLD & BB, blast

C-23-Sel-R, C-28-6 & C 11-A-41 (YLD+R)

ACIRP trial with Salivahan, Pranava & Swarna

Rep. trails- 8 location in 1996, 9 locations in 1997 9 locations in 1997 10 location in 1999

Screening in NSN (1997-99)BB & blast- 9 locationssheath blight- 10 locationstungro- 3 location

C 11-A-41 (38.2 & 21.4 % yld on B 32 & B 127)Res. To Blast & mod R to BB, tungro

Released in 2002 in AP, TN, KA, MH

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Yield performance of promising ILs derived from the cross O. sativa x O. rufipogon

Mean yield, range & % yield increase of Dhanrasi over high-yielding national check varieties

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High yielding ILs (IL50-7) derived from BC3F2-F8 of cross KMR3 x O. rufipogon (major yield QTL yld2.1), control KMR3

Aim: Comparing global gene expression of flag leaf and young panicle of IL50-7 with those of recurrent parent KMR3. Such a comparison would lead to discovery of novel yield-related genes/alleles from wild rice

Affymetrix rice genome array contained probe sets designed from 48,564 japonica and 10,260 indica gene sequences

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Number of differentially expressed genes & their fold change in leaf & panicle

Summary of fold change and sequence similarity (SS) of DEGs with the parents

Genomic regions of 10 out of 14 DEGs selected for validationwere amplified & sequenced

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Expression analysis of Os11Gsk and Os12Mat by semiquantitative RT PCR. Total RNA was isolated from leaves of KMR3 (K), O. rufipogon (R), IL50-7 (7), and IL50-13 (13) and gene-specific primers were used for amplification. EF1a was used as a control

Southern analysis showing additional bands in the genomic DNA of O. rufipogon and IL50-7 with Os11Gsk probe

Result: Os11Gsk is a wild rice-derived gene introduced in KMR3 background and increases yield either by regulating expression of functional genes sharing homology with it or by causing epigenetic modifications in the introgression line.

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45 accessions

>2000 ILs developed

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318 Test hybrids Check hybrid

318 selected ILs

Objective: to assess the effect of introgressions in heterozygous state

17 hybrids expressed a significant increase in yield over check hybrids

4 hybrids (ILH299, ILH326, ILH867 and ILH901) from O. rufipogon and 2 hybrids (ILH921 & ILH951) from O. nivara significant heterosis

Re-evaluation at large scale

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;

Four crosses, ILC 482 (C. arietinum) x ILWC 179 (C. echinospermum) ILC 482 x ILWC 124 (C. reticulatum) and their reciprocals

F1

F2

International Center for Agricultural Research in the Dry Areas (ICARDA), Syria, from 1987-95

Selected 22 F7 lines

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Out-yielded cultigen parent by up to 39% & also free of any known undesirable traits from wild species

Seed yield and yield-related traits of 22 F7

lines

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• In India Mulbery (Morus) is represented by four species i.e., M.indica L., M.alba L., M.laevigata and M.serrata

• Central Silk Board developed improved mulberry varieties through conventional, polyploid and backcross breeding. • Though varieties have more leaf yield/ quality aspects but in long term this

may not be suitable for specific condition. To bring greater diversity into the breeding pools, it requires introduction of unadapted and productive exotic or wild species • M. serrata: possess several agronomically important traits such as higher leaf

thickness, greater leaf moisture content, moisture retention and resistance to abiotic and biotic stresses (drought and frost)• M. laevigata: bigger leaf size, higher leaf thickness, moisture retention,

resistance to biotic and abiotic stress (drought, saline and frost) • They have scope for introgression breeding between wild and cultivated

species

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• IARI released ‘BG1103’ a drought and temperature tolerance chickpea variety derived from Cicer reticulatum, is a leading cultivar (40% more yield) in Northern India (S. Yadav)• Oryza rufipogon genes have been exploited for tolerance to

high acidic-sulfate content soil in Vietnam (Nguyen et al. 2003)• O. longistaminata genes for drought tolerance in cultivars of

Philippines, allowing the spread of rice production to previously unusable lands (Brar 2005)

Introgression for Tolerance to Abiotic Stresses

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• Triticum dicoccoides adaptively diversified from north-eastern Israel and the Golan into the Near East Fertile Crescent, across a variety of ecological conditions.• Fully compatible with tetraploid durum wheat and can be crossed with hexaploid

bread wheat

• H. spontaneum shares a survival niche with halophytic vegetation in the Dead Sea coast with only 50 mm/year precipitation

• Selfing annual grass of predominantly distributed in desert (Iran) & cold (Tibet)

• Cross compatible with cultivated barley.• which is one of the best genetic resources

for barley improvement in arid regions in the world

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• Arizona Genomics Institute (AGI) evaluated the performance of wild rice species (O . meridionalis and O . barthii , and EE genome O . australiensis) under summer (limited ppt. <2 mm and varying extreme temperatures 35– 43 °C) • Two heat-tolerant varieties, Arizona Rice – 1 and Arizona Rice - 2 , were

developed from a cross between one of the best accessions of O.meridionalis and O. sativa cv. M-202. • IRRI evaluated several ILs from O. sativa × O. rufipogon and O. sativa × O.

glaberrima at hotspots. • Elite breeding lines with good agronomic traits and moderate tolerance to

iron toxicity, aluminum toxicity, and acid sulfate conditions have been identified• CLRRI, Vietnam: 3 promising lines from O . rufipogon x IR64 were selected

and tested through the yield-testing network. lines, IR73678-6-9-B has been released as a variety (AS996) for commercial cultivation in the Mekong Delta, • It became popular & occupies 100,000 ha. It is a short-duration (95–100

days), semi-dwarf with good plant type suitable for moderately acid sulfate soils and is tolerant to BPH and blast

RICE

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Incorporation of CMS sources from wild species

Lin and Yuan, reported the development of male sterile line having

cytoplasm of wild species (O. sativa L. f. spontanea) and nuclear genome

of rice.

This wild species was found growing in Hainan Islands, China.

The cytoplasmic source has been designated as wild abortive (WA)- i.e

male sterile wild rice plant having abortive pollen.

Transferred to cultivated species through repeated backcross programme.

About 95% of the male sterile lines used in commercial rice hybrids

grown in China and other countries have WA type of cytoplasm.

(Yuan, 1993)

Rice

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Contd…

CMS based on using wild Helianthus annuus & H. petiolaris Nutt. has been used in high yielding commercial sunflower hybrids since 1972.

Currently, 100% of sunflower production in the US, and ~ 60–70% of production worldwide is estimated to be from these hybrids.

CMS and fertility restorer lines derived from Pennisetum purpureum Schum. were used in the first pearl millet grain hybrids & commercial forage hybrids (Hanna 1989)

Tifleaf series derived from these are the mostly widely cultivated in North America & Brazil

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• Large yellow and red flowers attract a number of insects which affect cross-fertilization (UP to 70 %)• For developing CMS lines in pigeonpea, ICPW 89 an Indian accession of Cajanus

scarabaeaides (L.) Thouars, a wild relative of pigeonpea and four pigeonpea lines ICPLs 87051, 87119, 88039 and ICP 8863

ICPLs 88039, 88034 & 81 maintainers

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Frequency (%) of fertile plants and average pod number in F1 hybrids between three CMS lines and 14 locally adapted cultivars of pigeonpea

Identification of Fertility Restorers

Complete restorer

Partial restorer

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List of CMS sources derived from different wild relatives of pigeonpea

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Improvement of quality

• Tomatoes have provided many classic examples of improved quality traits from wild genes, from increased soluble solid content, fruit color, and adaptation to harvesting

• Fruit size: L. pimpinellifolium (Tanksley and McCouch 1997)

• Doubling of protein content in a Brazilian cassava cultivar, ICB 300, derived from Manihot oligantha (Nassar 2003)

• Increased protein content in wheat cultivars derived from Triticum dicoccoides (Hoisington et al. 1999)

• Better grain quality synthetic hexaploid wheat cultivar ‘Carmona’(Spain)

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• Auxinic herbicides (2,4-D & Dicamba) are widely used in agriculture to selectively control broadleaf weeds. • Prolonged use of auxinic herbicides in wheat & barly in Canada has

resulted in the evolution of resistance to these herbicides in some biotypes of Brassica kaber (wild mustard).• Herbicide resistance is determined by a single dominant gene• Auxinic herbicide resistance was transferred from B. kaber to Brassica

juncea and Brassica rapa, by traditional breeding coupled with in vitro embryo rescue• To achieve embryo regeneration and plantlet formation via embryo

rescue, immature siliques (narrow, elongated seed capsules) were harvested 3 to 5 d after pollination & grown in MS+ Gamborg vitamins, 3% (w/v) sucrose, and 500 mg/l casein hydrolysate

Herbicide resistance

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Hybrid production between B. juncea, B. rapa, and B. kaber: frequency of embryo regeneration and hybrid plant establishment via in vitro embryo rescue

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Ovule/embryo rescue procedure to produce hybrids between B. juncea, B. rapa, and B. kaber. A, immature cultured silique; B, ovule excised from a silique; and C, hybrid plant regenerated from the ovule

B. juncea X B. Rapa X B. kaber

Note the hybrid exhibiting intermediatecharacteristics of parents

Production of via embryo rescue

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Dicamba resistance in hybrids and backcross progeny

1/10 hybrid of B. juncea × B. kaber and 10/32 hybrids of B. rapa × B. kaber were dicamba-R.

B. juncea B. rapa B. kaber

B. juncea × B. kaber B. rapa × B. kaber

B. juncea × B. kaber

F1B. juncea ×

BC1F1B. juncea ×

BC2F1

Plant response to dicamba (200 g ae/ha) 5 wk after treatment.

male fertile & female sterile

4 plants dicamba resistant

male fertile

B. rapa × B. kaber

F1B. rapa ×male fertile& female sterileAABB BB

AA BB

No seed set

Reported for the first time the successful production of hybrids and transfer of auxinic herbicide resistance from B. kaber to B. juncea × B. kaber hybrids

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Clearfield sunflower hybrids

• The original Clearfield trait in sunflowers – the ImiSun trait - is based on a natural acetohydroxy acid synthase (AHAS) mutation discovered in 1996 in a wild sunflower H. annuus L. growing in a soybean field in the United States. • In 2000, research and devt. (Nidera Semillas S.A.) confirmed trait has greater

crop tolerance regardless of environmental stresses, improved weed control, oil content and grain yield.• Herbicide resistance to imidazolinone and sulfonylurea chemicals used to

control broomrape (Seiler and Gulya 2004). AHAS enzyme that is insensitive or resistant to the inhibition of imidazolinone herbicides.• These genes have been transferred into cultivated hybrids under the trade

name ‘Clearfield’.• These resistance genes have been transferred into cultivated hybrids under

the trade name ‘Clearfield’, and are expected to be worth millions of dollars globally (G. Seiler)• BASF company is launching in the name of “Clearfield plus” sunflower

hybrids

Clearfield

Non-Clearfield

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Constraints of using CWR

Interspecific crossabilityEmbryo Rescue method

1. ex.: Cassava X Manihot glaziovii for transfer of cassava mosaic virus resistance (Akano et al. 2002)

2. Chickpea x C. pinnatifidum for resistance to asochyta blight

Biological constraints (blocks to hybridization and hybrid sterility)

Linkage dragMolecular techniques offer a partial solution but cases

where pleiotropic effects limit the use of genes from wild relatives.

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Future PrioritiesImproving molecular technologies, interspecific hybridization techniques

and genetic knowledge will continue to increase the capacity to use the valuable traits found in CWR

Search for new genes from diverse sources with wide spectrum of resistance in the wild species germplasm.

Identify resistance to major biotic and abiotic stresses where there is limited variability for the target traits in the cultivated species.

Allele mining to identify novel genes/QTL with different mechanisms of resistance and pyramid such genes/QTL

Identification and introgression of yield enhancing loci “wild species alleles” into elite breeding lines to further increase the diversity and yield potential of indica and japonica rice cultivars

Search for genes controlling homologous pairing to promote recombination and transfer genes from distant genomes of wild species

Intensify exploratory research on C4ness in wild speciesExplore the production of haploids particularly in indica rice through wide

hybridization (chromosome eliminating system in wheat and barley)Explore the production of biofuels from wild rice with high biomass yield

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Thanks for patience listening