稻曲菌中稻曲菌素与黑粉菌素合成基因的鉴定及功能分析

由病原真菌稻曲菌（Ustilaginoidea virens）引起的稻曲病已成为我国水稻栽培区最具破坏力的病害之一。由于研究基础薄弱，对该病害致病机理的了解十分有限。植物病原真菌通常会产生大量诸如毒素类的次生代谢产物，部分毒素在病原真菌的致病性中起到重要作用。该项目将在稻曲菌基因组研究的基础上，对其中稻曲菌素与黑粉菌素合成、修饰与调控基因进行预测，分析这些基因在侵染水稻过程中的表达与调控情况；其次，建立并优化稻曲菌基因敲除体系，对预测的基因进行敲除；随后，对获得的基因敲除体进行毒素的分离与测定，明确负责合成、修饰和调控稻曲菌素和黑粉菌素生物合成的基因；同时，通过接菌鉴定这些敲除体在水稻上的致病力，明确稻曲菌素或黑粉菌素合成与致病性之间的相关性；最后，测定水稻受毒素处理后的全基因组表达谱，分析预测毒素参与真菌致病性的分子机理。研究结果将为制定稻曲病的综合防控措施提供重要的信息。

Rice false smut, caused by the fungal pathogen Ustilaginoidea virens (Cooke) Takah, has become one of the most devastating diseases in rice worldwide. Given that it is an emerging disease, little is known about virulence and pathogenicity of U. virens. Phytopathogenic fungi often produce large amount of secondary metabolites including mycotoxins, which have been demonstrated to be involved in virulence of some phytopathogenic fungi. U. virens produces two types of mycotoxins, ustiloxins and ustilaginoidins. Based on available genome sequences of U. virens, the genes and pathways which may be involved in the biosynthesis of ustiloxins and ustilaginoidins will be predicted in the project. First, we will investigate the expression and regulation of these genes in planta during infection. Second, the highly efficient gene-knockout system will be developed for U. virens. Through this system, the gene-deletion mutants of these predicted genes will be constructed in U. virens. Subsequently, these mutants will be investigated for the content of mycotoxins and for virulence to rice. According to the resulting data, we can reveal the genes responsible for the biosynthesis, modification and regulation of mycotoxin production and find out if these mycotoxins play important roles in virulence of this pathogen. Fourth, gene expression profilings will be investigated in rice upon the treatment of mycotoxins and transcriptome analyses will be performed to understand molecular mechanisms how mycotoxins are involved in U. virens virulence. The expected results will provide important information for development of effective disease management strategies.