Assessment of KMR-3, MSN-36 and Tetep for Blast Disease of Rice

Abstract

In Karnataka, KMR-3 and MSN-36 are widely used as stable fertility restorers in hybrid rice production. However, hybrids developed from these restorer’s exhibit varying levels of blast susceptibility due to the susceptibility of the restorers themselves, which in turn affects the overall performance of the hybrids. Tetep is well known for its broad-spectrum resistance to diverse blast pathogen races prevalent in India and is routinely used as a resistant check for leaf blast disease screening at ZARS, V.C. Farm, Mandya, Karnataka. Since, data on blast disease resistance and the associated resistance genes are not available for KMR-3 and MSN-36, the present study was undertaken to assess level of resistance to blast disease and also to know the blast resistance genes present in KMR-3 and MSN-36 in comparison with the Tetep. This will help identify which resistance genes from Tetep can be targeted for introgression into the restorer lines through marker-assisted backcross breeding (MABB) to develop blast-resistant versions of KMR-3 and MSN-36. MSN-36, KMR-3 and Tetep were found to be highly susceptible, moderately susceptible, and moderately resistant, respectively in phenotypic screening conducted for blast disease in a uniform blast nursery. Genotyping of KMR-3, MSN-36, and Tetep with nine SSR markers linked to major blast resistance genes (Pi1, Pi54, Pi2, Pi9, Pi-km, Pi-tp(t), Pi-7(t), Pi40 and Pita/Pita2) showed that Pi1 and Pi9 were absent in all three genotypes. Pi2, Pi-7(t), and Pi40 were present in all three genotypes, Pi-km was unique to KMR-3, Pi54 was detected only in Tetep and Pi-tp(t) and Pita/Pita2 were present in KMR-3 and Tetep but absent in MSN-36. The study suggests that Pi54, Pi-tp(t), and Pita/Pita2 into MSN-36 and only Pi54 into KMR-3 from Tetep needs to be transferred to enhance blast resistance through MABB.