Inheritance of resistance in indica rice cultivar HUR 4-3 against bacterial leaf blight (Xanthomonas oryzae pv. oryzae)

摘要

The mode of inheritance of resistance to Xanthomonas oryzae pv. oryzae strain BXOl and BX043 (wild type) of bacterial leaf blight disease of rice was studied in six generations of crosses of cultivars HUR 4-3 into PB-1460. The resistant cultivar PB-1460 showed 4.54% disease severity, while susceptible cultivar HUR 4-3 showed 53.01% disease severity against Xanthomonas oryzae pv. oryzae. The area under the disease progress curve (AUDPC) of resistant cultivar was 65.61 which are significantly less thanthe susceptible on 649.90. The F, plants were observed to be resistant with an average disease severity 08.87% and AUDPC 110.26. The F2 populations were classified in to four distinct classes on their genotypic ratio of 9:3:3:1 and phenotypically thesepopulations were grouped in two distinct classes, resistant and susceptible with their ratio of 13:3, respectively. However, B, and B_2 populations were classified in to two distinct classes as resistant (resistant/ moderately resistant) and susceptible(moderately susceptible/ susceptible) in the ratio of genotypic 1:1:1:1 and 1:1 and phenotypically 1:1 and 1:0, respectively. The disease resistance occurs in the population is mainly due to cumulative effects of dominant and recessive resistant genes i.e., Xall and xal3. Chi-square analysis of the population confirmed the inheritance of resistance with their value of 1.24 and 0.66 indicating that the observed data are in line with expected ratio and follow Mendelian pattern of inheritance of resistanceto bacterial leaf blight in Bj and B_2 generations and modification in the Mendelian ratio of inheritance in the F, populations; it showed inhibitory gene action i.e., 13:3 that means dominant gene have cumulative effect with recessive gene.