SCREENING OF RICE GERMPLASMS FOR SHEATH BLIGHT RESISTANCE AND ASSESSMENT OF PARENTAL POLYMORPHISM USING SSR MARKERSShailesh Yadav, Ravi Ranjan Kumar, G Anuradha, VLN Reddy and R Sudhakar
Sheath blight disease, caused by the pathogenic fungus Rhizoctonia solani Kuhn, is one of the most prevalent rice diseases, causing severe damage to rice productivity worldwide. Absolute resistance to R. solani is not available in any of the rice germplasm cultivated globally. In the present investigation, 40 rice germplasm lines were screened for sheath blight resistance and parental polymorphism survey was carried out between moderated resistance and highly susceptible genotype using SSR markers located across the chromosomes. These 40 rice germplasm included 8 wild, 4 land races, 26 cultivated and 2 advanced breeding lines. A moderate level of resistance to this disease was identified in Tetep and ARC10531, a land race with the relative lesion height percentage of 21-30% while highly susceptibility was recorded in BPT 5204 with 80% relative lesion height. As Tetep is well known source for sheath blight resistance and mapping of quantitative trait loci involving this as a resistance source has been already reported earlier, so in present study ARC 10531 was selected as a contrasting moderate resistant parent with highly susceptible line BPT-5204 for parental polymorphic survey. Parental polymorphism involved 500 SSR markers spanning the entire 12 chromosome, among which 70 markers were found polymorphic among parental lines. The polymorphic marker percentage was about 14% between two parents ARC10531 and BPT-5204. The information on the identified new resistance source ARC 10531 and their polymorphic SSR markers would be useful to map the new QTLs governing sheath blight resistance.
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