MoCreA介导的稻瘟菌碳代谢阻遏途径及调控病菌生长和致病机制的研究

Carbon catabolite repression, CCR is a well known mechanism found in microbial organisms, which results in the preferential utilization of glucose from a mixture of carbon sources due to repress the genes encoding enzymes required for the utilization of less favored carbon compounds. There are significant differences in mechanisms to control CCR among fungi, though CCR are widely existed. During its infection and colonization in rice, Magnaporthe oryzae, a model of fungal pathogen faces challenges of nutrient limitation and carbon stress. The CCR should play an important role in control of development and pathogenicity of this fungus. Our previous researches showed that the carbon catabolite repressor MoCreA of M. oryzae involved in CCR and fungal development and pathogenicity. In this project, the techniques of bioinformation, real-time PCR, gene knockout, fluorescent labeling, co-immunoprecipitation, MALDI-TOF-MS analysis and RNAseq will be used to study the function of MoCreA, analysis of its interaction proteins and to reveal the mechanisms to control CCR in this fungus. The roles of genes that regulated by CCR in development, conidiation and pathogenicity of the fungus will be also studied in this project. Our results will help to understand the molecular mechanisms of pathogenicity in this fungus and its interaction with rice. The results will also help to better understand the mechanism of CCR in filamentous fungi.

代谢物阻遏（carbon catabolite repression, CCR）是指微生物在混合碳源发酵时优先利用速效碳源，且该碳源的代谢产物会抑制非速效碳源利用的现象。尽管CCR广泛地存在于各种真菌中，但它们的调控机制差异很大。稻瘟病菌作为重要的模式病菌，在侵入和定殖寄主的过程中面临着各种营养的限制和碳源的胁迫，因此，CCR途径在调控该菌的生长发育和致病性中可能有着重要的功能。我们前期的研究发现，稻瘟病菌碳代谢阻遏子MoCreA参与CCR调控，并初步发现其与病菌生长和致病相关。本项目在此研究基础上，利用基因敲除、免疫共沉淀、蛋白质谱分析和高通量测序等技术，进一步深入研究MoCreA的功能，寻找其互作蛋白，解析其控制的CCR信号网络，揭示其调控病菌生长、产孢和致病的机制。为进一步分析稻瘟病菌致病及其与寄主互作的分子机理提供理论依据，并为丝状真菌CCR机制的研究提供借鉴。

代谢物阻遏（carbon catabolite repression, CCR）是指微生物在混合碳源发酵时优先利用速效碳源，且该碳源的代谢产物会抑制非速效碳源利用的现象。稻瘟病菌在侵入和定殖寄主的过程中面临着各种营养的限制和碳源的胁迫，因此，我们推测CCR途径在调控该菌的生长发育和致病性中有着重要的功能。本项目研究发现，稻瘟病菌中包含一个与酵母（Mig1）和构巢曲霉（CreA）碳代谢阻遏子同源的蛋白MoCreA。功能分析发现，MoCreA蛋白参与稻瘟病菌的生长、产孢和致病性，并且调控稻瘟病菌的碳代谢阻遏。亚细胞定位发现，当有葡萄糖时，MoCreA进人细胞核抑制非速效碳源利用相关基因的表达，当缺失葡萄糖时，MoCreA进入细胞质被降解从而解除对相关基因的阻遏。进一步的研究发现，MoCreA除了调控非速效碳源利用相关基因的表达来参与CCR外，该蛋白还通过调控许多产孢和致病相关基因的表达来影响病菌的产孢和致病性。我们的研究还发现，MoCreB、MoCreC、MoCreD和MoUbp8等蛋白也参与了稻瘟病菌的CCR过程，其中MoCreD参与泛素化降解MoCreA，起到去碳代谢阻遏的作用，而MoCreB、MoCreC和MoUbp8与之相反，负责去泛素化MoCreA，使其发挥阻遏子的功能。MoCreB 和MoCreD与病菌的生长和致病无密切关系，而MoCreC和MoUbp8与稻瘟病菌的生长、产孢和致病都密切相关。我们的研究进一步丰富了丝状真菌中碳代谢阻遏调控的理论，并进一步揭示了稻瘟病菌生长发育和致病的分子调控机制，为今后稻瘟病防治药剂的开发提供了潜在靶标。