氰烯菌酯抑制小麦赤霉病菌DON毒素形成的机理研究

Fusarium graminearum, the major causal agent of Fusarium head blight (FHB) disease, results in significant yield loss in infected grains. In addition, it also contaminates the grains with potent mycotoxins such as deoxynivalenol (DON) and its derivatives, harmful to humans, animals. Thus, it is urgent to develop bi-fungicides that could simultaneously suppress FHB disease and reduce DON contamination. Our previous results indicated that phenamacril (JS399-19), a widely used fungicide in China, showed high efficacy against FHB and inhibited DON production. Until now, we have identified that the molecular motor myosin I (FgMyo1) was the drug target of JS399-19. However, the mechanism of DON reduction affected by this fungicide is largely unknown. In this proposal, we will identify components of the DON biosynthesis cellular organelle named "DON-toxisomes", analyze their biological functions, and explore the FgMyo1 mediated-pathway of DON-toxisome traffic in hyphae. Ideally, our prospective results will explain the role of JS399-19 during the toxisomes formation and traffic, and finally determinate the mechanism of JS399-19 in the prevention of DON biosynthesis. The expected accomplishments can provide useful guidance for the development of new fungicides targeting myosin I. It will be benefit for the management of FHB and mycotoxin DON in the future.

小麦赤霉病及其产生的脱氧雪腐镰刀菌烯醇（DON）毒素严重威胁我国小麦的产量和质量安全。生产中迫切需要既防治赤霉病害又抑制DON毒素的杀菌剂。我们前期研究发现对赤霉病有特效的杀菌剂氰烯菌酯能有效抑制DON毒素形成。研究药剂的作用机制发现，该药剂靶标是病菌肌球蛋白FgMyo1，但其控制毒素形成的机理还不清楚。本项目将重点解析DON毒素合成场所“DON毒素合成小体”的关键组分及其生物学功能，明确氰烯菌酯抑制毒素合成小体形成的机理；阐明氰烯菌酯干扰分子马达FgMyo1复合体，进而阻断DON毒素在细胞内定向转运的分子机制。预期研究结果为后续筛选或研制既防病又抑毒的新型肌球蛋白抑制剂提供科学依据。

由禾谷镰刀菌和亚洲镰刀菌等引起的小麦赤霉病是当前影响我国小麦安全生产的重大真菌病害。同时，病菌在侵染时会产生DON毒素（脱氧雪腐镰刀菌烯醇，Deoxynivalenol）严重污染小麦及麦制品的食品安全。解析病菌合成DON毒素合成机制对研发高效防赤霉病和DON毒素具有重要意义。本项目针对DON毒素胞内合成细胞器不清楚及其调控不明确等问题开展研究。研究结果发现：1.在病菌致病和产DON毒素诱导条件下，胞内内质网重塑形成DON毒素体，为DON毒素合成提供合成场所；2. 肌球蛋白FgMyo1与肌动蛋白Actin互作对DON毒素体形成起关键作用，氰烯菌酯靶向FgMyo1抑制该蛋白活性，显著抑制毒素体形成；Actin加帽蛋白FgCapA和FgCapB影响Actin的组装，参与毒素体形成；3. 三酰甘油降解产生磷脂为毒素体形成提供组分，过氧化物酶体降解胞内脂肪为DON毒素合成提供初始原料乙酰辅酶A；4. 鸟苷酸交换因子Cdc25和组蛋白乙酰化修饰参与调控毒素体形成和DON毒素合成；5. 生防菌ZJU60分泌的吩嗪-1-甲酰胺和杀菌剂氰烯菌酯能够靶向DON毒素体，达到抑制DON毒素合成的目的。本研究结果明确了DON毒素胞内合成场所，解析了DON毒素体形成的分子机制，为后续研发防控DON毒素技术奠定了坚实理论基础。