水稻白叶枯病菌中一个新致病因子受寄主诱导及其调控致病性的机制研究

由黄单胞菌水稻致病变种（Xanthomonas oryzae　pv. oryzae, Xoo）引起的水稻白叶枯病是我国水稻生产上一种重要的细菌病害。在前期工作中，申请者通过蛋白组学技术和系统突变，从Xoo中鉴定了一个新的致病相关基因xanA，发现该基因在病菌侵染过程（互作3h、6h、12h）中受寄主水稻（初步鉴定为小分子营养物质）持续诱导表达；同时发现该基因通过不依赖生长的某种未知的机制来调控病菌碳源代谢和胞外多糖的生物合成，进而调控病菌的致病性。本项目拟以xanA为切入点，从寄主水稻中鉴定诱导xanA表达的化学物质；从病菌中鉴定介导xanA受水稻诱导表达的关键因子；探索化学物质与关键因子的互作关系；研究xanA受诱导表达后调控Xoo致病性的生化与分子机制。研究结果将有望揭示一种新的Xoo致病机制，同时为通过阻断这种诱导表达途径实现水稻白叶枯病的防控提供理论依据和新的策略。

Xanthomonas oryzae pv. oryzae (Xoo) is one of the most important bacterial pathogens that causes bacterial blight (BB) of rice in China. In previous works, we identified a novel pathogenic factor XanA through proteomic analysis and systematic mutation. The results showed that XanA is continuously induced (interaction for 3h, 6h, 12h) by host chemicals (probably nutrient signals), and we further found that XanA regulate Xoo carbohydrate metabolism, EPS synthesis and pathogenesis through a growth-independent and yet-to-be identified mechanism. Therefore, the aims of this project are to: (i) identify the host-derived chemical signals that induce expression of XanA at protein level; (ii) identify Xoo key factors that mediate XanA induction by host ; (iii) explore the potential interaction between the host-derived chemical signals and the Xoo key factors; (iv) demonstrate the regulatory mechanism of XanA in virulence of Xoo at biochemical and molecular level. Our results are expected to reveal a novel mechanism of XanA in the regulation of virulence of Xoo, and also provide a new strategy for control of BB of rice by interrupting the XanA-mediated interaction between host and Xoo.