Non-hypersensitive leaf rust resistance of bread wheat cultivar PBW65 conditioned by genes different from Lr34

Abstract

The bread wheat (Triticum aestivum L.) cultivar PBW65 has shown hight levels of resistance to the most frequent and highly virulent Indian race 77-5 of leaf rust (Puccinia triticina). The infection type and disease severity indicated a non-hypersensitive type of resistance against the race 77-5 in PBW65. The cultivar PBW65 was crossed with the leaf rust susceptible cultivar WL711 to determine the mode of inheritance of the resistance. The segregation for resistant and susceptible plants in the F2 and F3 generations revealed, that two genes, each showing additive effects, were likely to confer resistance to leaf rust in PBW65. Intercrossing of PBW65 with Cook (Lr34), RL6058 (Lr34) and HD2009, possessing a similar resistance level like PBW65, revealed that the genes for leaf rust resistance in PBW65 were non-allelic to Cook (Lr34), RL6058 (Lr34) as well as to the gene(s) in HD2009. It is concluded that the cultivar PBW65 is a novel source of non-hypersensitive leaf rust resistance.