Virulence and diversity of Blumeria graminis f. sp. tritici populations in Henan Province, China

Abstract Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici ( Bgt ), is an important disease affecting wheat production in Henan Province, China. In this study, 915 isolates from 2011 to 2020 were obtained from 14 cities/counties, virulence assessment was conducted, and SSR markers were employed to analyze the population in 2020. Virulence frequencies, pathotypes, and virulence complexity of the Bgt population from 2011 to 2020, and the population structure of Bgt in 2020 were analyzed. The results demonstrated that (1) no virulent isolates were detected against gene Pm21 ; (2) the virulence frequencies for genes Pm16 , Pm24 , PmHYM , Pm2 + Ta , Pm2 + Mld , Pm2 + 6 , and Mlxbd remained below 30%; and (3) the virulence frequency for gene Pm2 showed a progressive decline over the study period. The virulence of allisolates, composed of 710 pathotypes, and the analysis of virulence complexity revealed a relatively low diversity. Moreover, the principal component analysis (PCA) of the virulence structure accounted for only 27.78% of the total virulence variation, indicating the virulence profile remained relatively homogeneous from 2011 to 2020 in Henan. The virulence and SSR marker data derived from the Bgt population in 2020 were analyzed using Popgen32 software, revealing no significant correlation between virulence and genetic diversity. The genetic diversity primarily resulted from within-population differences, which accounted for 92.02% of the total variation. The populations were grouped into four clusters, mainly based on geographical proximity, and exhibited extensive gene exchange among populations in 2020. These results provide valuable insights for the rational utilization of Pm genes and enhance our understanding of the diversity in Bgt populations in Henan.