Race composition and genetic diversity of a Puccinia striiformis f. sp. tritici population from Yunnan and Guizhou epidemiological regions in China in 2018

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is an extremely destructive wheat disease worldwide. Yunnan and Guizhou provinces are the main overwintering regions for Pst and inoculum sources for the disease in China. Surveillance of race dynamics of the Pst population is essential for managing the disease in local and other wheat-growing regions of China. However, Pst population dynamics in this region is not monitored yearly. In this study, a Pst population of 113 isolates from Yunnan and Guizhou in 2018 were phenotyped on the two wheat differential sets and analyzed by 12 simple sequence repeat (SSR) markers. As a result, 25 races were identified from the Pst population on Chinese differentials and predominant races was CYR32 with a frequency of 17.70%. None of the isolates was virulent to Yr5 and Yr15. Only a few isolates showed virulence to YrTr1 and differentials Zhong 4. The Kosman index (K) of the Pst population was 0.292 on the Chinese differentials, and 0.274 on single Yr gene lines and additional differentials, respectively. In total, 64 MLGs were detected among 113 isolates and the expected heterozygosity (He) was 0.424. A close genetic relationship was detected between Lufeng (Yunnan) / Nayong (Guizhou), Fuyuan (Yunnan) / Bijie (Guizhou), and Shizong (Yunnan) / Xingyi (Guizhou). This study provided useful information on population structure and virulence to Yr genes in the Yunnan and Guizhou epidemiological regions, and will be used to guide the control of wheat stripe rust and targeted wheat breeding in this region. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s42161-022-01273-1.