Tagging major quantitative trait loci for sheath blight resistance in a rice variety, Jasmine 85

This study was conducted with a clonal F-2 population of rice from a cross between Jasmine 85, a resistant variety, and Lemont, a susceptible cultivar . The rice plants belonging to each F-2 clone were divided into two plots, which were put in two replicates, respectively. Clonal parents were tested as controls. The plants were inoculated by short toothpicks incubated with RH-9, a virulent isolate of the pathogenic fungus, Rhizoctonia solani, whic h causes rice sheath blight. The extreme resistant and susceptible clonal l ines were selected for construction of resistant and susceptible DNA pools, respectively. A total of 94 polymorphic markers evenly distributed on 12 r ice chromosomes were used for bulked segregant analysis, three positive one s were found polymorphic between the two DNA pools, and three major QTLs fo r sheath blight resistance, Rh-2, Rh-3 and Rh-7, were identified. The three major QTLs were located on chromosomes 2, 3 and 7, and could explain 14.4% , 26.1% and 22.2% of the phenotypic variation.