水稻白叶枯病菌效应因子XopAY在病原菌与水稻互作过程中的作用

Ⅲ型分泌系统效应因子（T3SE）是病原菌与宿主互作的重要调节因子。水稻白叶枯病菌（Xoo）是最重要的水稻病原细菌，分泌的T3SE在致病过程中起关键作用。我们近期研究发现1个T3SE（XopAY）对Xoo的侵染至关重要。缺失突变XopAY导致Xoo致病力显著下降。在水稻中表达XopAY使水稻生长发育受阻，抗病力减弱。这说明XopAY参与Xoo与水稻的互作，但不清楚水稻中何种蛋白介导以及XopAY如何调控这一过程。本研究通过两方面的实验来揭示XopAY的调控机制。第一，筛选、鉴定XopAY在水稻中的靶标蛋白，并研究靶标蛋白在水稻生长及抗病响应中的作用。第二，体内、体外相结合的方式分析XopAY的生化功能，解析其调控靶标活性的机制。通过这些分析，将剖析XopAY的功能及调控通路，为白叶枯病的防治提供理论基础。

Most gram-negative animal and plant pathogens use the type Ⅲ secretion systems (T3SSs) as a basic virulence mechanism. T3SSs inject proteins (named effectors, T3SEs) into eukaryotic cells, where T3SEs facilitate bacterial growth and pathogenesis by specifically interfering with host cell signal transduction and other cellular processes. Individual T3SS translocates a variety of unrelated T3SEs, which account for species-specific pathogenesis phenotypes. .Xanthomonas oryzae pv. oryzae (Xoo) is the causative agent of bacterial leaf blight in rice, which is the most destructive bacterial diseases of this crop. Xoo depends on its T3SS and associated T3SEs to grow and colonize the vascular tissues of rice plants. T3SEs in Xoo include a family of closely related transcription activator-like (TAL) effectors and the rest of diverse non-TAL effectors. Although the TAL effectors have been extensively studied, our understanding of non-TAL effectors in Xoo remains limited. .To best understand the functions of these non-TAL effectors in Xoo, we have recently deleted these 18 non-TAL effectors genes from PXO99 genome and studied the virulence of these mutants. Beside the known virulence-related effectors, we have also isolated the XopAY as a vital T3SE for Xoo pathogenesis. Deletion of xopAY from Xoo genome caused this pathogen showed decreased virulence to rice plant. Moreover, expression of XopAY in rice (TP309) led to reduced height, low seed setting and increased susceptibility to pathogens. These data indicates that XopAY plays an essential role in Xoo-rice interaction. However, there is a large gap between XopAY and the plant defense response. What rice cellular components are required for XopAY signaling and how do they regulate plant growth and defense are still unknown. In this study, we will uncover the mechanism of XopAY signaling by two strategies. One is the identification of the interaction proteins in rice of XopAY by yeast two hybrid and Co-Immunoprecipitation, and the functions of these interactors. The interaction proteins might act as XopAY receptors involved in the regulation of rice growth and defense. The other is the study of XopAY activity in vivo and in vitro, and the modification pattern of the targets by XopAY. The regulatory pathway and mechanism involved in XopAY signaling will be mined by combining these studies. With the help of genetic analysis, protein-protein interaction studies, enzyme activities assays as well as bioinformatic methods, the regulatory pathway of XopAY signaling will be constructed.