Virulence Characterization of Puccinia striiformis f. sp. tritici in China in 2020 Using Wheat Yr Single-Gene Lines

Wheat stripe (yellow) rust, caused by the fungus Puccinia striiformis f. sp. tritici (Pst), is one of the most threatening wheat diseases worldwide. Monitoring the virulence of Pst population is essential for managing wheat stripe rust. In this study, 18 wheat Yr single-gene lines were used to identify the virulence patterns of 67 isolates collected from 13 provinces in China in 2020, from which 33 Pst races were identified. The frequency of virulence to different Yr genes varied from 1.49% to 97.01%, with 4.48% to Yr1, 26.87% to Yr6, 11.94% to Yr7, 95.52% to Yr8, 19.40% to Yr9, 11.94% to Yr17, 2.99% to Yr24, 35.82% to Yr27, 38.81% to Yr43, 97.01% to Yr44, 8.96% to YrSP, 1.49% to Yr85, 95.52% to YrExp2, and 7.46% to Yr76. None of the isolates were virulent to Yr5, Yr10, Yr15, and Yr32. Among the 33 races, PstCN-062 (with virulence to Yr8, Yr44, and YrExp2) and PstCN-001 (with virulence to Yr8, Yr43, Yr44, and YrExp2) were the prevalent races, with frequencies of 28.36% and 11.94%, respectively. These results provide valuable information for breeding resistant wheat cultivars for controlling stripe rust.