Tri和Pks基因簇多态性与禾谷镰刀菌毒素合成的关联性解析

脱氧雪腐镰刀菌烯醇(DON)和玉米赤霉烯酮(ZEN)是禾谷镰刀菌产生的有害次级代谢产物，已成为粮食生产和食品安全的重大隐患。毒素的发生和毒性存在较大差异，这一现象可能与病原菌的遗传变异有关。DON和ZEN的产生分别由Tri和Pks基因簇所决定，前期基于相关基因Tri10和Pks4的研究表明，多态性丰富的群体合成毒素的能力显著提高，具体机制还不清楚。本项目将以不同寄主和地区的禾谷镰刀菌为研究对象，测定它们的毒素合成水平，对毒素合成基因簇组件进行序列分析，明确毒素合成能力差异与编码基因多态性的相关性；筛选可能导致毒素合成能力变异的单核苷酸多态性位点，构建基于这些位点的定点突变体，明确单一位点变异对菌体毒素合成水平及毒素合成基因簇上所有元件和其它调控基因表达水平的影响。本研究结果期望为进一步揭示禾谷镰刀菌毒素合成的调控机制提供理论依据。

Deoxynivalenol (DON) and Zearalenone (ZEN), toxic secondary metabolites produced by Fusarium graminearum, are major risk to grain production and food safety. However there are large differences between the occurrence and toxicity of these toxins, which may be associated with pathogen population structure and genetic variation. Synthesis of DON and ZEN are controlled by Tri and Pks gene cluster, respectively. Our previous research based on Tri10 and Pks4 discovered that the population with abundant polymorphism showed the highest production of mycotoxins, but its mechanism is remain unclear. Therefore, toxins producing abilities and gene sequences in the cluster of F. graminearum strains from various hosts or locations will be analyzed. Then, we attempt to clear the correlation between the diversity of toxin synthetic level and encoding gene polymorphism based on genetic diversity of F. graminearum populations. After that, we will screen single nucleotide polymorphism sites that may lead to the variety of toxin producing ability and site-directed mutants on those sites will be constructed to determine the effect of single nucleotide mutation on toxin synthetic ability and expression levels of elements in the gene cluster and other regulatory genes. At last, gene expression profile of wild type and site-directed mutant will be compared and we hope to reveal the molecular mechanism of SNP site regulating toxin production. This research can provide theory basis for further reveal regulation mechanism of toxin synthesis in F. graminearum.