Improvement of Stable Restorer Lines for Blast Resistance through Functional Marker in Rice ( L.).

Two popular stable restorer lines, CB 87 R and CB 174 R, were improved for blast resistance through marker-assisted back-cross breeding (MABB). The hybrid rice development program in South India extensively depends on these two restorer lines. However, these restorer lines are highly susceptible to blast disease. To improve the restorer lines for resistance against blasts, we introgressed the broad-spectrum dominant gene into these elite restorer lines through two independent crosses. Foreground selection for was done by using gene-specific functional marker, at each back-cross generation. Back-crossing was continued until BC and background analysis with seventy polymorphic SSRs covering all the twelve chromosomes to recover the maximum recurrent parent genome was done. At BCF, closely linked gene-specific/SSR markers, DRRM--10, -8, and RM 6100, were used for the identification of fertility restoration genes, and along with target gene (), respectively, in the segregating population. Subsequently, at BCF, plants, homozygous for the and fertility restorer genes ( and ), were evaluated for blast disease resistance under uniform blast nursery (UBN) and pollen fertility status. Stringent phenotypic selection resulted in the identification of nine near-isogenic lines in CB 87 R × B 95 and thirteen in CB 174 R × B 95 as the promising restorer lines possessing blast disease resistance along with restoration ability. The improved lines also showed significant improvement in agronomic traits compared to the recurrent parents. The improved restorer lines developed through the present study are now being utilized in our hybrid development program.