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

Oat anthracnose, primarily caused by Colletotrichum cereale , poses a significant threat to oat production in Northern China. Utilizing beneficial endophytes as biological control agents offers an eco-friendly strategy to manage this disease. Consequently, there remains a continuous need to explore novel indigenous microbial resources with reliable biocontrol potential. Bacillus amyloliquefaciens XJYM-Y9, an indigenous oat endophyte preliminarily confirmed via multilocus sequence analysis (MLSA), was evaluated for its biocontrol and plant growth promotion (PGP) potential. Dual-culture and greenhouse assays demonstrated significant antagonism against C. cereale , yielding an in vitro inhibition rate of 81.53% and an in vivo disease suppression efficacy of 80.58%. Furthermore, its cell-free supernatant (CFS) and crude lipopeptides (CLEs) induced morphological abnormalities in C. cereale mycelia. XJYM-Y9 also exhibited broad-spectrum activity against eight phytopathogens. Phenotypic assays confirmed its secretion of cell-wall-degrading enzymes (CWDEs), while PCR analysis established the genetic basis for lipopeptide biosynthesis. Following successful colonization across diverse oat tissues within 48 h, B. amyloliquefaciens XJYM-Y9 primed ISR-like defense responses in oat. Greenhouse assays supported the growth promoting potential of XJYM-Y9, as treated oat seedlings showed improvements in multiple growth parameters. In addition, field evaluations showed stable disease-control efficacy of 67.87% and a 21.59% increase in crop produce. These findings indicate that XJYM-Y9 coordinates direct antagonism, systemic colonization, and host defense activation to suppress oat anthracnose and promote growth. Its consistent field performance highlights its potential for sustainable oat disease management.