基于组学技术解析贝莱斯芽孢杆菌DJ1拮抗玉米茎基腐病菌机制

Multi-omics reveals the inhibition mechanism of Bacillus velezensis DJ1 against Fusarium graminearum

摘要:

贝莱斯芽孢杆菌(Bacillus velezensis) DJ1具有广谱拮抗植物病原真菌的活性，但其对玉米茎基腐病菌——禾谷镰刀菌(Fusarium graminearum)的生防机制尚未明确。本研究旨在通过基因组与转录组学联合分析解析DJ1的抑菌机制。结果表明，菌株DJ1对玉米茎基腐病菌的抑制率达64.4%，其聚酮粗提物对玉米茎基腐病的盆栽防效达55%。该菌株基因组为单一环状染色体(3 929 792 bp，GC含量47%)。全基因组中共注释到12个次级代谢产物生物合成基因簇，其中6个编码已知抗菌化合物，包括大环内酯H、杆菌烯、地非西丁、表面活性素、丰原素及杆菌霉素等。转录组分析共鉴定到243个可能与DJ1拮抗玉米茎基腐病菌相关的差异表达基因(上调152个，下调91个，P < 0.05)，KEGG功能富集分析显示半胱氨酸/甲硫氨酸代谢、戊糖磷酸途径及聚酮类生物合成通路显著激活(P < 0.05)，说明该菌株通过合成抗菌物质、增强能量与代谢、营养竞争等多种机制协同抑菌。本研究为开发新型防治病原真菌的种质资源与应用技术提供了理论依据。

Abstract:

Bacillus velezensis DJ1 exhibits broad-spectrum antagonistic activity against diverse phytopathogenic fungi, while its biocontrol mechanisms against Fusarium graminearum, the causal agent of maize stalk rot, remain poorly characterized. In this study, we integrated genomics and transcriptomics to elucidate the antifungal mechanisms of strain DJ1. The results demonstrated that DJ1 inhibited F. graminearum with the efficacy of 64.4%, while its polyketide crude extract achieved the control efficacy of 55% in pot experiments against this disease. Whole-genome sequencing revealed a single circular chromosome (3 929 792 bp, GC content of 47%) harboring 12 biosynthetic gene clusters for secondary metabolites, six of which encoded known antimicrobial compounds (macrolactin H, bacillaene, difficidin, surfactin, fengycin, and bacilysin). Transcriptomic analysis identified 243 differentially expressed genes (152 upregulated and 91 downregulated, P < 0.05), which were potentially associated with the antagonistic activity against F. graminearum. KEGG enrichment analysis highlighted activation (P < 0.05) of cysteine/methionine metabolism, pentose phosphate pathway, and polyketide biosynthesis pathways, indicating that DJ1 employed synergistic strategies involving antimicrobial compound synthesis, energy metabolism enhancement, and nutrient competition to suppress pathogens. This study provides a theoretical foundation for developing novel microbial resources and application technologies to combat phytopathogenic fungi.