转录因子MoMsn2调控稻瘟病菌脂肪酸代谢和致病力的分子机制研究

The organisms possess a robust and well-evolved mechanism to address environmental stress. Response to such stress requires a complex network of sensing and signal transduction mechanisms that include transcriptional regulation of genes. Fatty acid metabolism plays a critical role in the development and virulence in fungal pathogens. Our previous study revealed that transcription factor MoMsn2 controlled the development, stress response and pathogenicity by modulating the transcription level of a series of downstream genes in the rice blast fungus Magnaporthe oryzae. Moreover, the localization of MoMsn2 was shifted from cytoplasm to nucleus under salt stress treatment. Recently, our latest results found that MoMsn2 could be shifted from cytoplasm to nucleus when treated by oleate, glycerol and galactose. Besides, the ∆Momsn2 mutant showed a growth defect in the medium with oleate, glycerol and galactose as sole carbon source. These results indicated that MoMsn2 probably plays a role in fatty acid metabolism in M. oryzae. However, the underlying regulatory mechanism of MoMsn2 during this process is unclear and was not reported. Therefore, we are trying to uncover this mechanism in this project. Firstly, the role of MoMsn2 in degradation and utilization of fatty acids will be clarified. Secondly, chromatin immunoprecipitation sequence (ChIP-Seq) approach will be adopted to identify the target genes and binding sites of MoMsn2 under the treatment of oleate. Thirdly, the biological functions of conserved or novel target genes which related to fatty acid metabolism will be characterized. The results will eventually uncover the molecular mechanism of MoMsn2 during fatty acid metabolism and pathogenicity of the rice blast fungus; and will also provide potential targets for novel fungicide designment based on the fatty acid metabolism related pathway.

生物体进化形成了复杂的信号分子网络应答和适应外界环境胁迫，其中包括基因的转录调控。脂肪酸代谢在病原真菌的生长发育及致病中具有至关重要的作用。项目组前期发现转录因子MoMsn2控制稻瘟病菌的生长发育和致病力，且其定位在盐胁迫下从细胞质向细胞核转移。我们最近的研究发现，在油酸等碳源的诱导下，MoMsn2也会从胞质向细胞核转移。同时，∆Momsn2突变体利用油酸等碳源的能力下降，表明MoMsn2参与病菌的脂肪酸代谢，但其具体的调控机制尚不清楚。因此，本项目拟阐明MoMsn2在病菌脂肪酸降解和利用过程中的功能；采用ChIP-Seq技术鉴定油酸诱导条件下MoMsn2的靶基因及其结合位点；解析脂肪酸代谢途径靶基因在病菌致病中的功能；挖掘新的参与脂肪酸代谢的靶基因并解析其功能。研究结果可望揭示MoMsn2调控稻瘟病菌脂肪酸代谢和致病力的分子机制；为开发以该代谢途径重要蛋白为靶标的新型药剂提供试验依据。

生物体进化形成了复杂的信号分子网络来应答和适应外界环境胁迫，其中包括基因的转录调控。脂肪酸代谢在病原真菌的生长发育及致病中具有至关重要的作用。项目组前期发现转录因子MoMsn2控制稻瘟病菌的生长发育和致病力，且其定位在盐胁迫下从细胞质向细胞核转移。同时，发现在油酸等碳源的诱导下，MoMsn2也会从胞质向细胞核转移，且∆Momsn2突变体利用油酸等碳源的能力下降，表明MoMsn2参与病菌的脂肪酸代谢，但其具体的调控机制尚不清楚。围绕这一科学问题，项目组在本项目的资助下开展了一系列研究，取得了以下研究进展：明确了MoMsn2在病菌脂肪酸降解和利用过程中的作用；鉴定到一系列MoMsn2的靶基因；解析了2个靶基因在稻瘟病菌脂肪酸代谢及致病中的生物学功能；揭示了MoMsn2 调控稻瘟病菌脂肪酸代谢和致病力的分子机制。研究结果深入了解了稻瘟病菌的致病分子机制，为开发以脂肪酸代谢途径重要蛋白为靶标的新型药剂提供了理论基础。主要研究结果如下：.一、明确了MoMsn2在病菌脂肪酸代谢中的作用，发现MoMsn2主要参与对长链脂肪酸的降解过程。.二、鉴定到一系列MoMsn2的靶基因。采用ChIP-seq技术鉴定到332个MoMsn2的潜在靶基因，发现这些基因参与病菌的多种代谢过程。.三、解析了靶基因MoDCI1和MoPCS60在稻瘟病菌脂肪酸代谢及致病中的生物学功能。发现两者均受外源脂肪酸诱导表达，通过调控病菌过氧化物酶体的生物合成，参与脂肪酸代谢和侵染菌丝扩展。.四、揭示了MoMsn2 调控稻瘟病菌脂肪酸代谢和致病力的分子机制。发现MoMsn2在外源油酸处理条件下和侵染早期从胞质向细胞核转移，随后激活靶基因MoDCI1和MoPCS60的表达，促进病菌的脂肪酸代谢。MoLrp1很可能作为响应外源脂肪酸的受体，通过响应该信号激活cAMP信号通路，诱导MoMsn2从胞质向细胞核转移。