Multiple disease resistance of an Australian bread wheat cultivar Cook

Wheat (Triticum aestivum L.) cultivar Cook showed significant levels of resistance to the highly virulent Indian race 77–5 of the leaf rust (Puccinia triticina) and race 46S119 of stripe rust (P. striiformis). Infection type studies indicate that the cultivar Cook expresses a non-hypersensitive type of resistance against both diseases. Cultivar Cook was crossed to the leaf rust and stripe rust susceptible cultivar WL711 to determine the nature, number and mode of inheritance of genes governing this resistance. The segregation for resistant and susceptible plants in F2 and F3 generations revealed that two genes each showing additive effects govern resistance to leaf rust and stripe rust. The F3 generation also segregated for powdery mildew resistance, while the cultivar Cook showed significant levels of resistance to Karnal Bunt compared to susceptible cultivar WL711. It is concluded that cultivar Cook is a source of multiple disease resistance genes.