Isolation and biocontrol potential of the indigenous endophyte Bacillus amyloliquefaciens XJYM-Y9 from oat leaves against oat anthracnose

Background Oat anthracnose (OAE), primarily caused by Colletotrichum cereale , poses a significant threat to oat production in Northern China. Utilizing beneficial endophytes as biological control agents offers a promising and eco-friendly strategy to manage this disease. Consequently, there remains a continuous need to explore novel microbial resources with reliable biocontrol potential. Results In this study, Bacillus amyloliquefaciens XJYM-Y9—an endophyte isolated from healthy oat foliage and taxonomically confirmed via multi-locus sequence analysis (MLSA)—was evaluated for its multifaceted biocontrol and plant growth promotion (PGP) potential. Dual-culture assays demonstrated that XJYM-Y9 exhibited robust antagonistic activity against C. cereale and a broad antifungal spectrum. Genomic mining and enzyme assays identified various biosynthetic gene clusters (BGCs) and cell wall-degrading enzymes (CWDEs) associated with its antifungal and colonization functions. Notably, XJYM-Y9 exhibited promising PGP potential, significantly improving the growth parameters and biomass of oat seedlings in greenhouse trials. Furthermore, RT-qPCR analysis revealed that XJYM-Y9 effectively primed ISR by upregulating six key antioxidant defense-related genes. Visualization using GFP-labeled XJYM-Y9 confirmed its systemic colonization across oat roots, stems, and leaves within 48 hours. Crucially, two-year, multi-location field trials analyzed via Linear Mixed Models (LMM) validated the stable efficacy of XJYM-Y9, which afforded a 67.87% control efficacy against OAE and a 21.59% increase in grain yield. Conclusions Collectively, these findings suggest that B. amyloliquefaciens XJYM-Y9 is a promising and reliable microbial resource for the integrated management of oat diseases and the promotion of oat productivity.