雷帕霉素抑制禾谷镰刀菌DON毒素合成的机制研究

由禾谷镰刀菌引起的小麦赤霉病不仅引起严重的产量损失，病菌在感病麦粒产生的脱氧雪腐镰刀菌烯醇（DON）等镰刀菌毒素还严重威胁农产品的质量安全。探索既能防病又能控毒的小麦赤霉病防控技术是保障小麦安全生产的迫切需求。项目前期从麦田土壤中筛选到一株对禾谷镰刀菌的生长、致病及DON毒素合成有良好抑制作用的吸水链霉菌S89，鉴定其拮抗物质为雷帕霉素。研究雷帕霉素的防病抑毒机制发现，该天然活性物质作用于TOR信号途径，通过抑制TOR激酶活性，进而促进组蛋白乙酰转移酶Gcn5的降解。Gcn5介导的组蛋白乙酰化修饰是病菌DON毒素合成基因（TRIs）转录激活的前提条件。在此基础上，本项目进一步解析雷帕霉素促进病菌Gcn5蛋白降解、进而抑制DON毒素合成的分子机理，研究结果将为镰刀菌毒素合成调控及其防控提供新思路。

Fusarium graminearum is an important plant pathogen, causing Fusarium head blight (FHB) on various cereal crops. In addition to yield losses, mycotoxins such as deoxynivalenol (DON) produced by F. graminearum in infested grains poses a serious threat to the quality and safety of agricultural products. Therefore, it is necessary to develop novel environmental-friendly strategies against both FHB and mycotoxins. In the early stage of this project, we identified the Streptomyces hygroscopicus S89, which can inhibit the fungal growth, virulence and DON production of F. graminearum. Our results showed that an active antifungal compound rapamycin secreted by the bacteria directly inhibited the kinase activity in TOR pathway and further promoted the degradation of acetyltransferase Gcn5. Proper histone acetylation mediated by Gcn5 is required for the transcription activation of DON biosynthesis genes (TRIs). We will further explore the mechanisms of rapamycin treatment in promoting the degradation of Gcn5 protein and inhibiting the synthesis of DON toxin. The expected results will provide theoretical support for the application of rapamycin against DON.