Genetic diversity and population structure of Puccinia striiformis f. sp. tritici reveal its migration from central to eastern China

This study focused on Puccinia striiformis f. sp. tritici (Pst), the causal pathogen of wheat stripe rust in China. The central and eastern China are the main wheat-producing areas in the country, and the occurrence of wheat stripe rust can cause severe yield losses. To determine the population genetic structure and potential pathways of migration among regional populations of the pathogen, 264 isolates were sampled during spring 2017 and genotyped using 12 simple sequence repeat (SSR) loci. The highest genetic diversity was detected in Hubei Province, indicating its potential role as one of the source populations for the rust epidemics. A high gene flow was detected among regional populations, supporting migration of Pst among regions. The significant decrease in genotypic and genetic diversity from Hubei to Shandong suggested that the migration direction was from central to eastern China. Analysis of molecular variance (AMOVA), Bayesian assignment, and principle coordinate analysis all indicated two major groups, one was mainly distributed in Hubei and the another was mainly in the eastern region. Shared genotypes, gene flow among regions, and Bayesian assignment tests revealed that the migration of Pst from central to eastern of China during spring occurred mainly through stepwise movement.