Inheritance of stem rust resistance in Indian bread wheat cultivars

Abstract

Four Indian bread wheat cultivars viz., DL788-2, GW322, Raj3765 and UP2425 were genetically analyzed against three selected pathotypes 21 (9G5), 40A (62G29) and 117A (36G2) of Puccinia graminis tritici at Indian Agricultural Research Institute, New Delhi. The segregation pattern in seedlings of F2 derived from crosses with Agra Local as susceptible parent showed the presence of three dominant independent genes for stem rust resistance in DL788-2 and Raj 3765, and two dominant independent genes in each GW322 and UP2425 when analyzed with pathotype 21 (9G5). These findings were supported by segregation of F2 seedlings of reciprocal crosses (AL x parent), in same pattern and reconfirmed by analyses of BC1 and BC2 progenies to test pathotypes. The F2 seedlings of all the diallele crosses did not segregate for susceptibility to pathotype 21 (9G5). It indicated that resistance gene(s) may be common in test cultivars, however, some of the diallele crosses showed segregation to pathotypes 40A (62G29) and 117A (36G2) showing dissimilarity of resistance. Genes Sr24in DL788-2, Sr1 1 in GW 322 and Sr31in UP2425 were validated based on pedigree and infection types of cultivars, and confirmed by test of allelism. An adult plant resistance gene Sr2was also identified in all these test cultivars based on mottling effect in the seedlings.