Poster89: Rice Panicle blight, An emergent disease in Colombia
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Rice Panicle Blight: An emergent disease in Colombia Fory, P., Prado, G., Aricapa, G., Correa, F., and Mosquera, G. Rice Pathology CIAT Km 17 Recta Cali Palmira Colombia INTRODUCTION Rice Pathology . CIAT , Km 17 Recta Cali-Palmira, Colombia. [email protected]INTRODUCTION Rice panicle blight produced by Burkholderia glumae has been reported in several rice‐producing countries around the world. Since the first report of this bacterium in 1989 (Zeigler and Alvarez), the disease was never reported as an important problem affecting rice production in Latin America In 2007 important yield losses due to the disease were reported America. In 2007 important yield losses due to the disease were reported by rice producers in the Caribbean coast of Colombia. This disease affect grain yield directly because the bacteria infect panicles in flowering stage interfering with kernels filling (Fig 1A). Symptoms can also appear on seedling stage as long brown lesions on sheath and leaves. There was no report of molecular identification of this bacterium in Figure 2. Greenhouse activities as part of information diffusion workshop • Primer specificity was confirmed by sequencing analysis of PCR product (Fig 3B). One hundred percent of homology with B. glumae There was no report of molecular identification of this bacterium in Colombia, previous identification was based on pathogenicity and biochemical tests. For the first time we are reporting the identification of panicle blight causal agent, B. glumae, using molecular approaches complementing pathogenicity tests. Here we are reporting a specific detection method based on PCR reaction confirmed by DNA sequencing was obtained from blast search against gene bank database. A B Filled detection method based on PCR reaction, confirmed by DNA sequencing, in which B. glumae was detected on symptomatic and apparently healthy seeds collected on Colombian rice fields . In the same way, yellowish pigment on solid media has been reported as selection criteria for B. glumae (Fig 1B). Preliminary results show that could be some physiological variation among B glumae strains isolated from natural Up seeds a)empty b)filled Down seeds c)empty c)filled Controls Empty physiological variation among B. glumae strains isolated from natural infected seeds. Figure 3. A, rice grains affected by the disease. B, PCR amplification obtained from macerated seeds. • Not all B. glumae colonies were pigment producers (Fig 1B and 1C). A non‐pigmented strain that was PCR positive and pathogenic on seedlings was also isolated (Fig 1C) A seedlings was also isolated (Fig 1C). • Parallel to PCR analysis, bacterial isolation on agar plates was also performed. Likely colonies were purified and used on pathogenicity test on rice seedlings (Fig 4). B C Figure 1. A, panicle blight symptoms on infected field and B, typical colonies of its causal agent B. Figure 4 Symptoms produced by B glumae on rice seedlings 7 days after inoculation glumae on King B agar plates. MATERIALS and METHODS • Infected plant material (panicles) collected from fields in Cordoba and Sucre (Colombia). Figure 4. Symptoms produced by B. glumae on rice seedlings 7 days after inoculation.. CONCLUSIONS • Development of a diagnostic method based on PCR allowed the specific detection of B glumae on rice contaminated seeds. L t ti f b t il t t l d • Three weeks old Colombia 21 variety seedlings obtained from certified seeds. • B. glumae specific primers for 16‐23S intergenic ribosomal region amplification reported by Sayler et al, 2006. • Low concentrations of bacterial present on symptomless seeds were also detected by our diagnostic method. • Bacterial strains isolated from positive samples for PCR induced symptoms on rice seedlings. • Strains identified as B glumae by PCR and pathogenicity tests h d i bl hl lt RESULTS • PCR‐based detection method allowed specific detection of B. glumae on symptomatic rice seeds. Information diffusion was done to Universities and local research institutes by mean of workshops (Fig 2). • PCR method sensitivity was assessed by serial dilutions of pure culture showed variable morphology on agar plates . • Sequencing data will allow to determine if pigment production could remain as an indicator in B. glumae identification. • Research on last emerging rice panicle blight disease is in progress because it can substantially affect rice production. • PCR method sensitivity was assessed by serial dilutions of pure culture of B. glumae. The minimal number of bacteria that was detectable by PCR was 100 bacteria per reaction. • Filled seeds from an infected panicle were also subject of PCR detection assay (Fig 3A). B. glumae was detected on asymptomatic seeds where the bacteria concentration was about 1000 bacteria compared with ten References Sayler, R.J., Cartwright, R.D., and Yang, Y. 2006. Plant Disease 90: 603‐610. Zeigler, R.S., and Alvarez, E. 1989. Plant Disease 73:368 the bacteria concentration was about 1000 bacteria, compared with ten times more obtained from symptomatic grains. Funding: Fontagro Project No. FTG‐311/2005
1. Rice Panicle Blight: An emergent disease in Colombia Fory,
P., Prado, G., Aricapa, G., Correa, F., and Mosquera, G. Rice
Pathology CIAT, Km 17 Recta Cali Palmira ColombiaPathology. CIAT
Cali-Palmira, Colombia. [email protected] INTRODUCTION Rice
panicle blight produced by Burkholderia glumae has been reported in
several riceproducing countries around the world. Since the first
report of this bacterium in 1989 (Zeigler and Alvarez), the disease
was never reported as an important problem affecting rice
production in Latin America. America In 2007 important yield losses
due to the disease were reported by rice producers in the Caribbean
coast of Colombia. This disease affect Figure 2. Greenhouse
activities as part of information diffusion workshop grain yield
directly because the bacteria infect panicles in flowering stage
interfering with kernels filling (Fig 1A). Symptoms can also appear
on Primer specificity was confirmed by sequencing analysis of PCR
seedling stage as long brown lesions on sheath and leaves. product
(Fig 3B). One hundred percent of homology with B. glumae There was
no report of molecular identification of this bacterium in was
obtained from blast search against gene bank database. Colombia,
previous identification was based on pathogenicity and biochemical
tests. For the first time we are reporting the identification
ofFilled A panicle blight causal agent, B. glumae, using molecular
approaches complementing pathogenicity tests. Here we are reporting
a specific B detection method based on PCR reaction confirmed by
DNA sequencing reaction, sequencing, Up seedsDown seeds Controls in
which B. glumae was detected on symptomatic and apparently
healthya)emptyb)filled c)empty c)filled seeds collected on
Colombian rice fields . In the same way, yellowish Empty pigment on
solid media has been reported as selection criteria for B. glumae
(Fig 1B). Preliminary results show that could be some physiological
variation among B glumae strains isolated from naturalB. Figure 3.
A, rice grains affected by the disease. B, PCR amplification
obtained from macerated infected seeds. seeds.A Not all B. glumae
colonies were pigment producers (Fig 1B and 1C). A nonpigmented
strain that was PCR positive and pathogenic on seedlings was also
isolated (Fig 1C)1C). B Parallel to PCR analysis, bacterial
isolation on agar plates was alsoperformed. Likely colonies were
purified and used on pathogenicitytest on rice seedlings (Fig 4). C
Figure 1. A, panicle blight symptoms on infected field and B,
typical colonies of its causal agent B. gpgy p yp g Figure 4
Symptoms produced by B glumae on rice seedlings 7 days after
inoculation4. B.inoculation.. glumae on King B agar plates.
MATERIALS and METHODS CONCLUSIONS Development of a diagnostic
method based on PCR allowed the Infected plant material (panicles)
collected from fields in Cordobaspecific detection of B glumae on
rice contaminated seeds.and Sucre (Colombia). ( ) L concentrations
of b t i l present on symptomless seeds Lowt tif bacterial tt ld
Three weeks old Colombia 21 variety seedlings obtained fromwere
also detected by our diagnostic method.certified seeds. Bacterial
strains isolated from positive samples for PCR induced B. glumae
specific primers for 1623S intergenic ribosomal regionsymptoms on
rice seedlings.amplification reported by Sayler et al, 2006.
Strains identified as B glumae by PCR and pathogenicity testsshowed
variable morphology on agar plates . h d i bl h ll t RESULTS
Sequencing data will allow to determine if pigment production
PCRbased detection method allowed specific detection of B. glumae
could remain as an indicator in B. glumae identification. on
symptomatic rice seeds. Information diffusion was done to Research
on last emerging rice panicle blight disease is in progress
Universities and local research institutes by mean of workshops
(Fig 2). because it can substantially affect rice production. PCR
method sensitivity was assessed by serial dilutions of pure culture
of B. glumae. The minimal number of bacteria that was detectable by
References PCR was 100 bacteria per reaction.Sayler, R.J.,
Cartwright, R.D., and Yang, Y. 2006. Plant Disease 90: Filled seeds
from an infected panicle were also subject of PCR detection 603610.
assay (Fig 3A). B. glumae was detected on asymptomatic seeds
whereZeigler, R.S., and Alvarez, E. 1989. Plant Disease 73:368 the
bacteria concentration was about 1000 bacteria compared with ten
bacteria, times more obtained from symptomatic grains.Funding:
Fontagro Project No. FTG311/2005
