Virulence Characterization and Population Structure of Puccinia striiformis f. sp. tritici in Henan Province, China

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), poses a significant threat to wheat production, particularly in Henan Province, which produces more than 36 million tons of wheat grain every year, the highest production among all provinces in China. This study characterized 219 Pst isolates collected from the five regions of Henan through virulence testing using two sets of wheat differentials and genotyping with 23 Kompetitive allele-specific PCR (KASP) markers developed from single nucleotide polymorphism (SNP) markers. Based on the virulence phenotypes on the Chinese differentials, 37 races were identified, including 17 new races. CYR34, CYR32, and G22-14 were the top three most prevalent races across the province. The virulence profiles varied among the five regions. The tests of the isolates with the Yr single-gene differentials revealed 75 races. None of the isolates were virulent to either Yr5 or Yr15, whereas the virulence frequencies to the other 16 Yr genes varied from 10 to 85% in the province and were slightly different among the five regions for each virulence factor. The Pst populations from the five regions were clustered into two major groups based on the two sets of differentials and the KASP-SNP marker data. These findings provide valuable insights for developing wheat cultivars with effective resistance for enhancing stripe rust management and improving wheat yields in Henan Province and the country.