稻瘟病菌过氧化物酶体增殖关键因子PEX11家族的构成及调控机制研究

稻瘟病菌的侵染依赖孢子贮藏脂肪的迅速转化。作为脂肪代谢的主要场所，过氧化物酶体（P）的产生与增殖对致病性至关重要。项目组曾对稻瘟病菌P产生机制开展研究，而P增殖机制未有报道。PEX11家族是调控P增殖的关键因子，不同物种中该家族构成与功能不同，真菌中尤不明确。通过序列分析，我们发现稻瘟病菌中有3个可能的该家族成员，并分别获得了单、双及三敲除突变体。本项目拟在上述基础上，通过表型分析，结合基因表达、蛋白定位及酵母互补等方法明确这3个基因：1，是否定位于P；2，是否与酵母PEX11同源；3，表达动态是否与P数量及P代谢相关；4，对P增殖、动态、相关生化代谢、病菌形态发育及致病性的作用；5.上下游基因及调控。从而确定稻瘟病菌PEX11家族的构成，并揭示其在P增殖及病菌致病过程中的作用及机制。本研究对稻瘟病菌致病机理与真菌P增殖机制的研究都具有重要意义，并可能为病害防治提供药物靶点。

The appressorium-mediated infection of the rice blast fungus Magnaporthe oryzae accompany with the rapid degradation and coversion of the spore-stored lipids. As the main organelles of lipid metabolism, peroxisomes proliferate rapidly to adapt the situation during the pre-penetration phase. The genes in PEX11 family are key factors regulating peroxisome proliferation. But to date, the numbers and roles of the PEX11s are obscure in M. oryzae. By sequence similarity, three possible PEX11 members in M .oryzae genome were　detected. Using the gene disruption strategy, we obtained their single-deleted, double-deleted and triple-deleted mutants. The aim of the present project is to clarify which is/are the true membrane(s) of PEX11s in M. oryzae, and explore their roles and functional details in peroxisomal proliferation and fungal infection. We will investigate in this project: 1st, which genes are localized in peroxisomes of M. oryzae by using fluoresent fusion assay; 2nd, which genes are highly expressed during peroxisomal proliferation; 3rd, which genes can restore the Δpex11 mutant of Saccharomyces cerevisiae via cross-complementation; 4th, what roles are executed by these genes in peroxisomal proliferation, peroxisomal metabolism (e.g. lipid metabolism and ROSs degradation), fungal development and host invasion by phenotypic analysis; and 5th, what are their related genes upstream or downstream by using quantitive PCR, BIFC and yeast two-hybrid strategies. The results of this research will be helpful to better understand the PEX11 family and peroxisomal proliferation mechanism in filamentous fungi, and as well provide possible gene targets for new pesticide screening.