Postulation of resistance genes to stripe rust in commercial wheat cultivars from Henan, Shandong and Anhui provinces.

Seedlings of 50 commercial wheat cultivars from Henan, Shandong and Anhui provinces, main winter wheat-growing areas in China, were inoculated with 26 selected differe-nt isolates of Puccinia striiformis to postulate stripe rust resistance genes. The data indicated that none of the cultivars was resistant to all the 26 isolates. Yr 9 presented in at least 17 cultivars, Yr 2 in 10 cultivars, and Yr 1 in 8 cultivars. Yr A, Yr 3 or Yr Sel presented in individual cultivars. Unknown resistance genes or gene combinations presented in other cultivars. Almost all the known genes in the cultivars tested are ineffective against dominant races of P. striiformis at present in China. It is urgent that breeding and using new wheat cultivars with effective resistance genes to stripe rust.