铜离子是细菌生长必需的微量元素，宿主通过在病灶区大量聚集铜离子从而防御病原菌入侵称为铜离子营养免疫。迄今为止，植物病原菌如何克服宿主铜离子营养免疫，从而成功致病的相关机制尚不清晰。.水稻黄单胞菌是水稻最重要的细菌性病原体，铜离子营养免疫是水稻防御该致病菌的一个经典模式。申请人前期在水稻黄单胞菌PXO99A单基因同框缺失文库中，筛选到三个铜离子耐受相关蛋白：包括经典铜离子耐受蛋白CopA和CopB，还有一个功能未知蛋白。深入研究发现，copA和copB基因的缺失不会导致致病力变化，而功能未知蛋白的缺失，导致其致病力的丧失。本项目以上述铜离子耐受蛋白为切入点，研究水稻黄单胞菌铜离子耐受机制；同时深入揭示铜离子耐受通路与致病信号通路的相关性。本项目将加深对微生物铜离子耐受机制的认识，同时揭示植物病原菌克服宿主铜营养免疫进而成功致病的分子机制，为定向强化植物铜离子免疫，增强植物抗病性奠定基础。

It is known that plant host exposes the pathogens to an excess of copper as a defense mechanism. In response, plant pathogens need to overcome this immunity for their successful infection. However, this immunity overcome mechanism is still unclear. .Xanthomonas oryzae pv. oryzae is a notorious rice pathogen that causes bacterial leaf blight (BLB), a destructive rice disease. The copper nutrient immunity is a classic mode for defense. Our previous study obtained three copper tolerance related genes from gene in-frame deletion library: including classic copper tolerance gene copA, copB and a hypothetical protein. We found that the absence of hypothetical protein reduced the virulence of Xanthomonas oryzae pv. oryzae (Xoo) sharply, while copA and copB deletion mutants could not impaired virulence. In this study, we are going to reveal the mechanism of copper tolerance in Xoo based on the previous study. We will focus on the intracellular copper homeostasis maintained by the mentioned functional unknown protein and the classical copper tolerance associated proteins. Furthermore, we will reveal the relationship between copper tolerance and the virulence of Xoo. This project would deepen our understanding about the mechanism how plant pathogens overcome nutritional immunity from host, as well as the microbial copper tolerance. These mechanisms are the theoretical basis for the plant diseases control.