Adult plant leaf rust resistance from 111 wheat (Triticum aestivum L.) cultivars

Adult plant resistance against Indian leaf rust race 77 and five of its hig hly virulent variants have been identified from 111 bread wheat cultivars o riginating from 12 countries. The adult plant resistance of only 16 of thes e cultivars is due to hypersensitive seedling or adult plant resistance gen es. All others expressed nonhypersensitive type of resistance characteristi c of the genes Lr34 and Lr46. Forty five of the 111 cultivars showed tip ne crosis on flag leaves, a trait linked to the gene Lr34. Therefore, the nonh ypersensilive type of resistance of these 45 cultivars is attributed to Lr3 4. The nonhypersensitive resistance of the remaining cultivars is likely to be due to the gene(s) different than Lr34. The reaction pattern of these 1 11 cultivars to six races suggests the presence of at least six to seven ne w hypersensitive adult plant resistance genes and at least three new hypers ensitive seedling resistance genes. The known genes Lr10, Lr23 and Lr26 wer e detected frequently but these genes did not contribute towards the adult plant resistance of any of the 111 cultivars. Based on the presence of new genes for hypersensitive and nonhypersensitive type of resistance, the 111 cultivars have been classified into 31 diverse resistance groups.