十字花科黑腐病菌（Xanthomonas campestris pv. campestris,简称Xcc）是引起十字花科植物黑腐病的病原菌，也是研究微生物与植物互作机理的模式菌。III型分泌系统和群体感应系统对病原菌的致病性具有非常重要的作用，有关T3SS和QS的表达调控一直是研究热点。前期发现Xcc中的一个新基因突变后，可使Xcc在甘蓝上致病力丧失及胞外多糖产量下降，而在基本培养基中却促进生长的有趣现象。生物信息学分析该基因无任何保守结构域特征，但在已测序的20多个黄单胞菌中高度保守，而其功能还未知，也未见其与致病相关的报道。本项目拟通过分子生物学和功能基因组学等各种手段，系统研究这个致病相关新基因。研究结果将阐明这新基因的功能、表达调控的模式及参与致病的具体方式。使人们在基因组和蛋白质组水平上了解该基因在致病过程中的作用，特别对控制有害生物危害的药物开发和设计上具有重要的指导意义。

The Gram-negative bacterium Xanthomonas campestris pv. campestris (hereafter Xcc) is the causal agent of black rot disease of cruciferous plants. The pathosystem of Xcc infect cruciferous plants is one-of the model system in studying micro-plant interaction. Type Three Secrete System(T3SS) and Quorum Sensing System (QS) play an important role with pathogenicity. Hence, T3SS and QS often catalyze quite specific reactions and are the subject of intense interest. In our previous research, we found that a new gene from Xcc 8004 genome is involved with the virulence of Xcc 8004 strains on host plants of cabbage and their ability to produce extrapolysaccharide after Tn5 mutant. It is very interesting that the mutant grows faster than the wild type Xcc 8004 in the MMX medium. The gene is encoding conserved hypothetical protein. To date, the role of the gene in Xcc is still unknow and no report about it associated with Xcc pathogenicity. This project will focus on in-depth study on the new gene in Xcc8004 by using different methods. The aim of this project is to investigate the physiological function of the new gene in Xcc 8004, especially to study its role in pathogenicity of Xcc by using molecule biology methods and function genomics techniques.The results will not only reveal its physiological roles but also unveil the mechanism of it in influencing the pathosystem of Xcc 8004, and will greatly extend our knowledge of this new gene affect virulence of this important phytopathogenic bacterium through the genomics and proteomics. It is especially helpful for exploiting and designing medicament to control the dangernous plant diseases.