Submergence stress is a major problem in Tamil Nadu during the monsoons. Every year paddy production is greatly affected due to flash floods. A major QTL on chromosome 9, Sub1 has provided the opportunity to apply Marker Assisted Backcrossing (MAB) to develop submergence tolerant versions of rice cultivars that are widely grown in the region. Present study was at aimed at marker assisted introgression of Sub1 locus controlling submergence tolerance from FR 13A into the background of CO 43, a popularly grown rice variety in the cauvery delta region. Molecular markers that were tightly linked with Sub1, flanking Sub1, and unlinked to Sub1 were used for foreground, recombinant, and background selection, respectively, in backcrosses between a submergence tolerant donor, FR 13A and the widely grown recurrent parent, CO 43. Polymorphic markers for foreground and background selection were identified. Genotyping and phenotyping of BC1 F1 and F2 generations revealed the superiority of the plants introgressed with Sub1 locus. By the BC2 F2 and BC3 F3 generations a submergence tolerant plant was identified that possessed 100% CO 43 genome with Sub1 locus. These backcross progenies were evaluated for their tolerance against flooding. All the plants were able to survive 11 days of complete flooding.
Key Words: Rice, Submergence tolerance, Marker assisted breeding, Genotyping, Phenotyping