泛素连接酶MoSkp1/MoCul1/MoFwd1调控稻瘟病菌分生孢子萌发和致病力的分子机制研究

The rice blast fungus Magnaporthe oryzae (anamorph: Pyricularia oryzae) is a model organism for exploring molecular biology in filamentous fungi and pathogenic mechanism of fungal pathogen. It causes rice blast disease worldwide posing threats to rice production. The ubiquitin system plays crucial roles in conidial germination, however, specific regulations of physiological and metabolic pathways remain unclear. By characterizing biological roles of 27 SCF-type ubiquitin ligase-related genes, we found that MoFWD1 is involved in controlling germination and virulence. Exogenous addition of glutamic acid and reduced glutathione could restore conidial germination defects apparently in ΔMofwd1. Based on methods of chemical biology, fungal genetics, biochemistry, and bioinformatics et al., we aim to reveal the dynamic changes of amino acid pools during conidial germination of M. oryzae and the molecular mechanism of MoSkp1/MoCul1/MoFwd1 regulating synthesis and assimilation of glutamic acid. The results of the program will supplement content of pathogenic mechanisms in the rice blast fungus in theory, meanwhile helping design new potential fungicide targets for controlling of rice blast disease in agricultural production.

稻瘟病菌是丝状真菌分子生物学和病原真菌致病机理研究的模式生物，其引发的水稻病害稻瘟病威胁着我国稻谷产量安全。泛素系统在稻瘟病菌孢子萌发过程中发挥重要调控功能，但具体的生理代谢调控通路尚不清楚。本项目前期通过对稻瘟病菌27个SCF型泛素连接酶相关基因的生物学功能初步分析发现MoFWD1在分生孢子萌发和致病过程中具有重要作用。外源添加谷氨酸和还原型谷胱甘肽可以显著恢复缺失突变体ΔMofwd1的孢子萌发缺陷。本项目拟借助化学生物学、真菌遗传学、生物化学和生物信息学等方法，揭示稻瘟病菌分生孢子萌发过程中孢子内氨基酸库的动态变化，明确泛素连接酶MoSkp1/MoCul1/MoFwd1调控谷氨酸合成和代谢进而调控孢子萌发的分子机制。理论上丰富稻瘟病菌致病机理的研究内容，同时农业生产上为稻瘟病的防治提供新的潜在药物靶点。

稻瘟病是水稻生产上重要的真菌性病害，由稻瘟病菌侵染水稻引起。本项目着重揭示稻瘟病菌分生孢子萌发的调控机制及对致病力的影响，我们通过酵母双杂交筛库获得MoFwd1的互作蛋白，同时结合线粒体是氨基酸的重要合成场所，选取线粒体相关的基因MoPsr1和MoRip1进行生物学功能分析。通过基因敲除，表型分析，生化分析和细胞生物学观察等方法，研究揭示MoPsr1调控稻瘟病菌生长产孢和致病力，其互作蛋白MoRip1参与稻瘟病菌ATP的合成进而影响生长分生孢子萌发和致病力，同时MoRip1参与氧化逆境响应和杀菌剂嘧菌酯抗药性。对比分析稻曲病菌分生孢子萌发，揭示表观阻遏因子UvKmt6通过调控H3K27me3修饰调节稻曲病菌分生孢子萌发和致病。在对分生孢子萌发机制阐释的基础上，我们面向应用分析了新型杀菌剂纳米银对稻瘟病菌分生孢子萌发和致病调控的作用机理，研究发现纳米银通过调控Pmk1信号通路和细胞自噬调节稻瘟病菌分生孢子萌发附着胞形成和致病力。除此之外，纳米银可以有效抑制嘧菌酯抗药性菌株Morip1的生长。本项目的研究结果为研发靶向分生孢子萌发的药剂和解决嘧菌酯抗药性问题提供理论基础。