Genetic Structure of Blumeria graminis f. sp. hordei Populations Causing Powdery Mildew on Barley

Abstract

Powdery mildew caused by Blumeria graminis f. sp. hordei is one of the most important foliar diseases affecting barley production worldwide, leading to significant reductions in grain yield and crop quality. Understanding the genetic structure of pathogen populations is essential for monitoring pathogen evolution and developing durable disease resistance strategies. The present study investigated the genetic structure of B. graminis f. sp. hordei populations collected from major barley-growing regions. Infected barley leaf samples exhibiting characteristic powdery mildew symptoms were collected from different agroecological zones, and fungal isolates were subjected to molecular characterization using polymorphic molecular markers. Genetic diversity, allelic variation, population differentiation, and phylogenetic relationships among isolates were analyzed to evaluate the population structure of the pathogen. The results revealed substantial genetic variability within and among B. graminis f. sp. hordei populations, indicating the presence of diverse pathogen genotypes across barley production areas. Certain populations exhibited close genetic similarity, while others showed significant differentiation associated with geographical origin and environmental conditions. Analysis of molecular variance demonstrated that most genetic diversity existed within populations rather than among regions, suggesting high evolutionary potential and possible gene flow among pathogen populations. The occurrence of genetically diverse populations may enhance the adaptability of the pathogen and increase the likelihood of overcoming host resistance genes in barley cultivars. Phylogenetic analysis further clarified evolutionary relationships and clustering patterns among isolates. The findings provide valuable insights into the epidemiology and evolutionary dynamics of powdery mildew pathogens and contribute to the development of effective resistance breeding and integrated disease management strategies for sustainable barley production.