Identification and pathogenicity of Blumeria graminis f. sp. poae the BGP(TG) strain isolated from Poa pratensis infected with powdery mildew in Shanxi Province

Abstract:

[Background] Poa pratensis is a species of widely used ornamental and facility cold-season turfgrass. Powdery mildew caused by Blumeria graminis f. sp. poae seriously reduces the lawn quality and shortens the service life of P. pratensis.[Objective] To isolate, identify, and determine the pathogenicity of the isolate BGP(TG) and provide a theoretical foundation for the prevention and control of powdery mildew in P. pratensis. [Methods] BGP(TG) isolated from a greenhouse of Shanxi Agricultural University was identified based on the morphological characteristics and ribosomal DNA internally transcribed spacer (rDNA-ITS) sequence. The pathogenicity of the isolate was determined with 23 samples of P. pratensis.[Results] The conidiospores of the pathogen were in chains, colorless, and oval, with the size of (23.31−34.67) µm×(11.33−15.77) µm and finger-like mature haustoria. The phylogenetic analysis based on rDNA-ITS sequences showed that the BGP(TG) isolate and B. graminis f. sp. poae shared the same branch. The pathogenicity tests showed that the disease index ranged from 14.41 to 53.12, and the incidence ranged from 49.47% to 77.72% nine days after 23 samples of P. pratensis were inoculated with BGP(TG). Only the native species ‘Taihang’ in Shanxi Province showed moderate resistance to BGP(TG).‘Yingxian’, ‘Black Jack’, and ‘Hunyuan’ showed moderate sensitivity, and ‘Explorer’ and ‘Award’ showed extreme sensitivity. The other 17 species showed high sensitivity, accounting for 73.91%. [Conclusion] The pathogenicity of BGP(TG) in Shanxi Province was strong. Mining the genes conferring resistance to powdery mildew from P. pratensis ‘Taihang’ will be of great significance for the breeding of P. pratensis with resistance to powdery mildew.