植物免疫反应会抑制自身生长发育，过强的免疫反应甚至导致植物细胞死亡。因此，免疫负调控因子是植物精确调控免疫反应不可缺少的调控元件。EDS1是非常重要的免疫正调控因子，几乎所有TIR-NB-LRR类型抗病蛋白激活的抗性依赖于EDS1。为研究EDS1信号通路中新的免疫负调控基因，我们通过正向遗传学筛选，得到了能恢复拟南芥感病突变体eds1对假单胞杆菌抗性的抑制子sed1和sed2。sed1和sed2抗性增强且无发育缺陷，因此其基因具有用于作物抗病遗传育种的潜力。本申请拟通过遗传学和生物化学方法，结合转录组和代谢组分析等手段，阐释SED1和SED2调控的基因网络和生理过程，揭示其分子机理。同时研究EDS1激活后，是否有对SED1或SED2功能的去抑制，阐释去抑制机制在植物免疫系统中的作用。本研究将增强我们对植物免疫系统调控的认识，并为抗病育种工作提供候选基因，具有重要的理论与实践意义。

In plants, the activation of immunity is often correlated with growth inhibition, and uncontrolled immune responses even result in plant cell death. Thus, negative regulators are essential for plants to fine tune the immune responses. EDS1 is an important positive regulator in plant immunity, as almost all TIR-NB-LRR receptors mediated resistance depend on it. To look for new negative regulators in EDS1 signalling, we performed a forward genetic screening and identified Arabidopsis mutants sed1 and sed2 as suppressors of eds1 in resistance to bacteria Pseudomomas syringae. As the sed1 and sed2 mutants show enhanced resistance but without obvious developmental defects, both SED1 and SED2 genes have great potential in breeding for disease resistance in crop plants. In this proposal, we will use genetic and biochemical approaches in combination with transcriptomic and metabolomic profiles to elucidate the negative regulation mechanisms of SED1 and SED2 in immunity. Moreover, we will investigate whether there is a de-repression of SED1 or SED2 in the activation of EDS1 signalling, to evaluate the de-repression mechanism in plant immunity. This study will increase our understanding on regulation of plant immunity and offer candidate genes for crop genetic breeding. Therefore, the study has great theoretical significance and applicable value.