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 highly virulent variants have been identified from 111 bread wheat cultivars originating from 12 countries. The adult plant resistance of only 16 of these cultivars is due to hypersensitive seedling or adult plant resistance genes. All others expressed nonhypersensitive type of resistance characteristic of the genes Lr34 and Lr46.Forty five of the 111 cultivars showed tip necrosis on flag leaves, a trait linked to the gene Lr34. Therefore, the nonhypersensilive type of resistance of these 45 cultivars is attributed to Lr34. The nonhypersensitive resistance of the remaining cultivars is likely to be due to the gene(s) different than Lr34. The reaction pattern of these 111 cultivars to six races suggests the presence of at least six to seven new hypersensitive adult plant resistance genes and at least three new hypersensitive seedling resistance genes. The known genes Lr10, Lr23 and Lr26 were 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. This revised version was published online in July 2006 with corrections to the Cover Date.