贝莱斯芽孢杆菌XY40-1：全基因组特征分析及对辣椒疫病的生物防治效果评价

Bacillus velezensis XY40-1: whole genomic characteristics and biocontrol effects on pepper Phytophthora blight

摘要:

【目的】 评估辣椒内生菌贝莱斯芽孢杆菌(Bacillus velezensis) XY40-1的生防能力和促生效果，了解菌株的抑菌机制，为辣椒疫病的生物防治菌剂研发提供优良菌种及技术理论支撑。【方法】 采用平板对峙、活体接种及显微镜观察法评估贝莱斯芽孢杆菌XY40-1对辣椒疫病的抑制效果和对辣椒的促生效果；采用基因组学和代谢组学方法确定其抗菌代谢物与拮抗功能物质合成通路，明确其抗菌机制。【结果】 菌株XY40-1对辣椒疫病、白绢病、炭疽病、黑斑病、枯萎病和根腐病6种病原真菌展现出较强的抑制效果，具广谱抗性。当菌液浓度为10⁷ CFU/mL时，其对辣椒疫病的防治效果可达66.13%。此外，该菌株还具有解磷、解钾和固氮能力，对辣椒苗具有明显的促生效果。菌株XY40-1携带大量酮类及萜类抗生素合成基因，能产生包括诺加霉素、大蒜素、利福昔明、西拉菌素、阿维菌素和安丝菌素P-3等在内的多种胞外代谢产物，这些代谢产物对病原真菌活性具有显著抑制作用。酮体的合成和降解、萜类骨架生物和抗生素合成通路均有助于菌株XY40-1的拮抗功能，其中，次生代谢产物的生物合成为其核心代谢通路。【结论】 辣椒内生菌贝莱斯芽孢杆菌XY40-1对辣椒疫病具有良好生防能力，同时兼具促生效果，可作为辣椒病害生物防治的多功能优质菌种。

Abstract:

[Objective] To evaluate the biocontrol and growth-promoting effects and reveal the antifungal mechanisms of the pepper endophyte Bacillus velezensis XY40-1, thus providing elite bacterial strains and technical support for the development of biocontrol agents for pepper Phytophthora blight. [Methods] Plate confrontation, in vivo inoculation assay, and microscopic observation were employed to determine the biocontrol and growth-promoting effects of B. velezensis XY40-1 on pepper. Genomics and metabolomics methods were adopted to determine the antifungal metabolites of the strain and the synthesis pathways of substances involved in antifungal effects, on the basis of which the antifungal mechanisms were explored. [Results] Strain XY40-1 exhibited strong inhibitory effects on six pathogenic fungi: Phytophthora capsici, Sclerotium rolfsii, Colletotrichum scovillei, Alternaria alternate, Fusarium oxysporum, and F. solani, that infected pepper, and it demonstrated broad-spectrum resistance. The strain suspension at 10⁷ CFU/mL showcased the control effect of 66.13%. Moreover, it possessed the abilities to solubilize phosphorus and potassium and fix nitrogen, thus promoting the growth of pepper seedlings. XY40-1 carried a large number of genes involved in the synthesis of ketone and terpenoid antibiotics, which enabled it to produce extracellular metabolites such as nogalamycin, megalomicin, rifaximin, avermectin ala, avermectin, and ansamitocin P-3 to inhibit pathogenic fungi. The synthesis and degradation of ketone bodies, as well as the biosynthetic pathways of terpenoid skeletons and antibiotics, contributed to the antagonistic function of XY40-1. The core metabolic pathway was the biosynthesis of secondary metabolites. [Conclusion] B. velezensis XY40-1, an endophyte of pepper, possesses excellent biocontrol and growth-promoting effects on pepper, being a multifunctional and high-quality strain for the biocontrol of pepper diseases.