ComA调控枯草芽胞杆菌NCD-2挥发性抑菌物异戊酸合成的机制研究

由大丽轮枝菌引起的作物黄萎病危害严重且难以防治，利用活体微生物杀菌剂是防治作物黄萎病是行之有效且绿色环保的措施之一。枯草芽胞杆菌NCD-2菌株为活性成份的微生物杀菌剂可有效防治棉花黄萎病。前期研究发现NCD-2菌株产生的挥发性气体对大丽轮枝菌菌丝生长和微菌核形成具有较强的抑制活性，证明异戊酸是挥发性气体中主要的抑菌活性成份。突变群体感应系统中的调控因子ComA基因显著降低了NCD-2菌株挥发性气体的抑菌活性和异戊酸合成能力。然而，ComA调控异戊酸合成的作用机制尚不明确。本项目拟通过代谢组学和转录组学分析ComA调控异戊酸合成的相关途径及关键基因，对关键基因进行缺失突变和互补，明确关键基因在异戊酸合成中的功能以及ComA对关键基因的调控方式。研究结果为阐明ComA调控异戊酸合成的作用机制奠定基础，同时有助于进一步明确NCD-2菌株防病机理，为NCD-2菌株的定向改造和高效应用提供理论指导。

Crop Verticillium wilt, caused by Verticillium dahliae, is a typical soil-borne disease and caused serious economic losses in agricultural production. Due to the lack of disease-resistant varieties, efficient chemical pesticides and suitable cultivation measures, it is difficult to effectively control Verticillium wilt. Using microbial fungicides is one of the effective and eco-friendly measures to control the disease. Bacillus subtilis strain NCD-2 could effectively control cotton Verticillium wilt. Previous studies showed that the volatile compound produced by strain NCD-2 could significantly inhibit the growth of hyphae and the formation of microsclerotia of V. dahlia, and the main antifungal active component in the volatile compound was isovaleric acid. Further study found that knocking out the regulatory factor ComA in quorum sensing system significantly reduced the antifungal activity of volatile compound and the ability of isovaleric acid synthesis in strain NCD-2. The mechanism of the regulation of isovaleric acid synthesis by ComA remained unclear. Therefore, this project intends to analyze the related pathways and key genes in the regulation of isovaleric acid synthesis by ComA through metabolomics and transcriptomics. The function of key genes in isovaleric acid synthesis and the regulation pathway on key genes by ComA will be determined through deletion mutation and complementation of key genes. This result lays an important foundation for elucidating the mechanism of the regulation of isovaleric acid synthesis by ComA. At the same time, it is helpful to further not only clarify the disease prevention mechanism of strain NCD-2, and but also provide theoretical guidance for the directed modification and efficient application of this strain.