Race Composition of Puccinia striiformis f. sp. tritici in Tibet, China

In Tibet, China, wheat stripe rust (caused by Puccinia striiformis f. sp. tritici) has recently become one of the most destructive diseases on winter wheat. To identify races of the pathogen in Tibet, 261 isolates were obtained in 2010 and tested on seedlings of a standard set of 19 wheat indicator genotypes. Of the 261 isolates, 248 were identified as members of 19 known races (CYR17, CYR20, CYR21, CYR22, CYR23, CYR29, CYR31, CYR32, CYR33, Lov13-6, Su11-1, Su11-2, Su11-3, Su11-4, Su11-5, Su11-6, Su11-7, Su11-8, and Su11-13), and 13 identified as representatives of 4 new races. CYR32 and CYR33 were the most predominant. The number of races and their frequencies in Tibet were more similar to the fungal populations in Sichuan and Gansu provinces than to those in Yunnan, Qinghai, and Shaanxi provinces. The results suggest that Tibet is also a possible center of inoculum source and genetic variation for the stripe rust pathogen in addition to Sichuan and Gansu.