Genetic analysis of blast resistant gene in rice (Oryza sativa L.) cultivars

The inheritance investigation uncovered that blast resistance in R 1013-2307-1-1, R 1124-91-2-73, R 1518-762-3-564-1, R 1558-2423-3-1445-1 and R 1559-2425-2-1449-1 was controlled by a single dominant gene, while two independent dominant genes governed resistance in R 1519-781-5-598-1 and R 1540-1888-1278-1. The allelic studies revealed that genes for resistance present in R 1013-2307-1-1, R 1518-762-3-564-1 and R 1558-2423-3-1445-1 was allelic to Pi-z5 (IRBL 10 and 5173). Among the blast differential genes (monogenic lines) tested, only 'Pi-z5' gene consistently imparted complete resistance against the blast population in the Northern Hilly Region of Chhattisgarh, Pi-z, Pi-9 and Pi-kh provided variable level of resistance. On the other hand four genes, Pi-z5, Pi-z, Pi-9 and Pi-kh are functional in Bastar Plateau (Jagdalpur). The severity of blast disease was considerably higher at Ambikapur station than at Jagdalpur so only one center (Ambikapur) could be reliably used to conduct screening trials. The race of the fungus at these two sites seems to be different. Eight genotypes viz., R 1518-762-3-564-1, R 1519-781-5-598-1, R 1540-1888-1278-1, R 1558-2423-3-1445-1, B 6441-FMR-6-0-0, F 7-10, IR42221-145-2-3-2 and 5173 showed consistently stable resistant reaction over the years.