Pathogenicity, genetic diversity and population differentiation of Pyrenophora graminea on highland barley in Qinghai Province.

Leaf stripe, caused by Pyrenophora graminea, is an important disease on highland barley in Qinghai province, China. The pathogenicity and genetic diversity of P. graminea from six regions of Qinghai province were examined. A total of 329 strains were collected, of which 230 were identified as P. graminea based on morphological characteristics and rDNA-ITS sequencing. The colony growth rate of P. graminea was evaluated on PDA plates and the most strains ranged from 25 to 30 mm/d, The pathogenicity of P. graminea was tested on two highland barley cultivars. Disease incidence on cultivar Caiqing 1 ranged from 0 to 44.4%, while that on Kunlun 14 ranged from 0 to 62.2%. Genetic diversity among the 230 strains was analyzed using 49 SSR markers. Genetic diversity in Xining (0.297 and 0.445) and Haibei (0.297 and 0.445) was higher than in other regions based on Nei's and Shannon indices, respectively. Population differentiation of P. graminea was observed among the six sampling regions. Strains were sorted into three molecular groups according to principal coordinate analysis (PCoA), hierarchical cluster analysis, and Bayesian structure analysis. The majority strains in Group 1 originated from Xingning and Haidong; Group 2 from Hainan and Huangnan, and Group 3 from Haibei and Haixi. These results provide valuable information for understanding the genetic diversity and population differentiation of P. graminea in Qinghai province and for developing management strategies for leaf stripe on highland barley.