禾谷镰孢菌致病相关基因FgSAMS的生物学功能研究

Fusarium head blight (FHB), mainly caused by Fusarium graminearum, and is an important disease on wheat at home and abroad. The occurrence of FHB not only reduces crop production severely, but also contaminates grain with toxic metabolites that are a big threat to human and livestock. Prevention and control of this disease is of great significance to China's food security. In the growth of wheat due to the limited effective fungicides, and the fungicide resistance occurred. Therefore, new fungicides must be synthesized to control this disease. The study on the pathogenic mechanism of pathogenic fungi is expected to find a new fungicide target, which is of great significance to the synthesis of new fungicides. The project applicant found that S-adenosylmethionine synthetase gene (SAMS) affected the pathogenicity of F. graminearum for the first time based on the existing research. Study on regulation of this gene on F. graminearum methionine synthase pathway, pathogenicity and toxin synthesis and sexual reproduction，by gene cloning, sequence analysis, model analysis, gene expression, gene knockout technology and reply. The purpose of the experiment is on the whole cognitive S-adenosylmethionine synthetase gene in F. graminearum in biological function and provide theoretical basis for controling of Fusarium head blight and discovering new drug targets and the design of new fungicides with high efficiency and low toxicity.

由禾谷镰孢菌（Fusarium graminearum）引起的赤霉病，是我国小麦生产中最为严重的病害之一，不仅造成严重的产量损失，而且病菌产生的毒素对人畜有毒害作用，威胁粮食安全和食品安全，防控好该病害对于我国的粮食安全具有重大意义。生产中由于有效杀菌剂有限，加之病菌抗药性的产生，必须研发新的杀菌剂。病原菌致病机制的研究有望发现新的杀菌剂靶标，对新型杀菌剂的研发具有重要意义。本项目拟选取前期研究基础获得的一个控制致病性的重要基因S-腺苷甲硫氨酸合成酶基因（FgSAMS）为研究对象，通过基因克隆，序列分析、基因表达模式分析、基因敲除与回复等技术手段，研究该基因对禾谷镰孢菌甲硫氨酸合成途径、致病性、毒素合成和有性生殖等方面的调控作用，旨在从整体上认知S-腺苷甲硫氨酸合成酶基因在禾谷镰孢菌中的生物学功能，为小麦赤霉病的防控和发掘新的药物作用靶标，设计新型高效、低毒、安全的杀菌剂提供理论依据。

由禾谷镰孢菌（Fusarium graminearum）引起的赤霉病，是我国小麦生产中的重要病害。病原菌致病机制的研究有望发现新的杀菌剂靶标，对新型杀菌剂的研发具有重要意义。本项目以禾谷镰孢菌S-腺苷甲硫氨酸合成酶基因（FgSAMS）为研究对象，通过克隆FgSAMS基因DNA序列和cDNA序列，利用Bioedit生物信息学分析软件进行比较分析，初步解析了FgSAMS基因的结构。通过基因敲除及回复等技术，获得了FgSAMS基因过表达突变体FgSAMS-OE、缺失突变体△FgSAMS和回复突变体△FgSAMS-FgSAMS。通过qRT-PCR测定了各突变体菌株中胱硫醚-γ-合成酶CGS和胱硫醚-β-裂解酶CBL基因的表达水平，明确了FgSAMS基因在禾谷镰孢菌甲硫氨酸生物合成途径中的作用。明确了FgSAMS基因过表达、缺失和回复对禾谷镰孢菌致病力的影响、毒素合成相关基因的表达水平的影响、DON毒素的合成、菌丝生长、产孢和有性生殖的影响，揭示了S-腺苷甲硫氨酸合成酶FgSAMS基因禾谷镰孢菌中的生物学功能。同时，明确了FgSAMS基因与禾谷镰孢菌对苯醚甲环唑、多菌灵、氰烯菌酯、氟唑菌酰羟胺及丙硫菌唑等杀菌剂的敏感性关系，为小麦赤霉病的防控和发掘新的药物作用靶标，设计新型高效、低毒、安全的杀菌剂提供理论依据。