十字花科黑腐病菌是研究微生物和植物相互作用的重要的模式菌株。III型分泌系统（T3SS）在寄主内和基本培养基中诱导表达，是植物病原菌最重要的致病系统之一。尽管目前已经鉴定了一些调节T3SS信号转导的组份，但在丰富培养基中抑制T3SS的基因还知之甚少。我们在十字花科黑腐病菌中发现一个新的双组份信号转导系统感受子基因，命名为rhpS。目前的实验结果显示，rhpS的突变体在丰富培养基中显著增强hrpX和T3SS的表达，且影响细菌在寄主中的生长繁殖和在非寄主中诱导的HR反应的能力。本课题旨在进一步通过遗传和生化手段，研究RhpS抑制T3SS信号途径的机制；并通过组学技术，明确RhpS下游关联基因，挖掘参与RhpS /T3SS信号途径新组份。T3SS作为细菌重要的致病因子分泌系统，对其调控表达机制的研究可以为植物病原菌的防控提供新策略。

Xanthomonas campestris pv. campestris is one of most important model phytopathogen in studying micro-plant interaction. The type III secretion system (T3SS) of plant pathogenic bacteria is induced in the plant host and the minimal medium, and is one of the key pathogenic system. Although several signaling components regulating the T3SS genes expression have been identified, however, little is known about the genes that inhibit the T3SS system in rich medium. We have identified a novel two-component signal transduction system (TCS) sensor gene rhpS repressing the expression of hrpX and T3SS genes in rich medium, influencing the ability of growth in host and trigger HR in non-host. This proposal is aimed at studying the mechanism of RhpS inhibiting T3SS signaling pathway through genetic and biochemical approaches; And through the group technology, clear RhpS downstream associated genes, mining new components involved in RhpS/T3SS signaling pathway. As an important pathogenic secretion system of bacteria, the study on the mechanism of regulation and expression of T3SS can provide a new strategy for the prevention and control of plant pathogens.