EVALUATION OF WILD RICE INTROGRESSION LINES FOR BROAD-SPECTRUM RESISTANCE TO BACTERIAL BLIGHT OF RICE

Bacterial blight of rice caused by Xanthomonas oryzae pv.oryzae has become a major threat to rice cultivation in irrigated and rainfed lowland ecosystem.In the absence of reliable chemical control strategies, deployment of resistant rice varieties is the most dependable and economical mean of managing the disease.Wild rices are the reservoir of novel genes against many biotic and abiotic stresses.In the present study, 44 introgression lines (ILs) from different accession of 9 species of wild rice were evaluated for their resistance to bacterial blight (BB) of rice.Three ILs viz., HWR 23 (IR 75084-15-3-B-B; derived from O. officinalis), HWR-36 (IR75083-49-25-9-5-B-B-B; derived from O. longistaminata) and HWR-42 (IR 75085-35-5-2-B; derived from O. officinalis) showed high level of resistance under field condition consecutively for two seasons against local strain (IX-020) of Xanthomonas oryzae pv.oryzae (Xoo).Another 7 ILs showed moderate to good level of resistance and rest showed susceptible reaction.Two ILs viz., HWR-36 and HWR-42 which showed high level of BB resistance were screened against 20 diverse strains of Xoo in glasshouse.These two selected ILs showed broad-spectrum resistance to 10-11 Xoo strains.Genotyping with gene-specific marker of 4 major BB resistance genes, viz., Xa21, xa13, xa5 and Xa38 revealed absence of these genes in these two ILs.Based on phenotyping and genotyping data, it can be assumed that these two ILs may possess new BB resistance source.