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Oral: Promising Phenotyping Efforts for Understanding Genetic and Molecular Bases of Plant Disease Resistance


Development of controlled high throughput and user friendly assays for host responses to rice pathogen isolates.
Y. JIA (1) (1) USDA-ARS Dale Bumpers National Rice Research Center, U.S.A.

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Rice sheath blight (SH) disease caused by the soil borne fungus Rhizocotonia solani AG1-IA is a major detrimental disease of rice in the USA and worldwide. The major genes for resistance to R. solani have not been identified, while genes providing minor phenotypic effects have been identified in several rice varieties worldwide. SH disease is currently managed with fungicides integrated into different cultural practices. The use of genetic resistance reduces production costs which is a preferred crop protection method. However, monitoring the resistance effect of minor genes is technically challenging because their phenotypic contributions are often masked by confounding factors including plant height, plant type (i.e., tiller angle), and days to heading. In the present study, 102 R. solani isolates from commercial rice fields in Arkansas were evaluated in vitro, and the slower growing isolates were identified for subsequent phenotyping analyses. A series of phenotyping methods, detached leaf, mist chamber, microchamber, and field plots with fungal biomass grown on potato dextrose agar plugs, tips of toothpicks, and a corn chop and rye mixture, were successfully used to evaluate genomic regions and candidate genes including an ABC transporter in rice that are responsible for resisting the infections by R. solani; and results will be presented.