Abstract: To investigate the changes of the structure and diversity of the phyllosphere microbial community after infection of Italian ryegrass （Lolium multiflorum） with Bipolaris sorokiniana， this study was conducted by artificially inoculating Italian ryegrass with B. sorokiniana spore suspension and collecting leaves of infected and healthy Italian ryegrass. High-throughput sequencing was used to investigate differences in the structure and diversity of the phyllosphere microbial community. Results showed that there were significant differences in phyllosphere microbial community structure， and the species richness and diversity of phyllosphere fungi and phyllosphere bacteria were higher in infected leaves than in healthy leaves. The dominant bacterial phylum was Proteobacteria and the dominant fungal phylum was Ascomycota. Functional prediction revealed a significant increase in potential pathogenic phenotypes following the infection of Italian ryegrass， with the Proteobacteria contributing substantially to the pathogenic phenotypes. Differences in abundance of Proteobacteria across groups were consistent with trends in pathogenicity phenotypes. This study provides a theoretical basis for the mechanism of plant phyllosphere microbial community responses to pathogen infection.

Key words: Lolium multiflorum, Bipolaris sorokiniana, Phyllosphere microbial community, Diversity, High-throughput Sequencing

摘要： 为探究多花黑麦草（Lolium multiflorum）感染离蠕孢（Bipolaris sorokiniana）叶斑病后叶际微生物群落结构和多样性的变化，本研究通过人工接种离蠕孢孢子悬浮液的方法制备离蠕孢叶斑病多花黑麦草，收集感病与健康多花黑麦草叶片，采用高通量测序研究多花黑麦草感病后叶际微生物群落结构和多样性差异。结果表明叶际群落结构差异显著，病叶叶际真菌、细菌的物种丰富度及多样性高于健康叶片。感病后叶际优势细菌门为变形菌门，优势真菌门为子囊菌门。功能预测发现多花黑麦草感病后的潜在致病性表型显著增加，其中变形菌门对致病性表型贡献较大，并且变形菌门在各组中的丰度差异与致病性表型变化趋势一致。本研究为植物叶际微生物对病原菌感染的响应机制提供理论依据。

关键词: 多花黑麦草, 离蠕孢叶斑病, 叶际微生物群落, 多样性, 高通量测序