How do plant resistance proteins activate defence gene expression upon effector perception?

植物抗病（R）蛋白使植物能够检测特定的病原体效应分子，然后激活防御，然而对R蛋白激活后的防御激活机制（抗病触发免疫，或ETI）知之甚少。拟南芥RPS 4和RRS 1抗性基因一起作用以检测两种不同的细菌效应蛋白，来自假单胞菌属的AvrRps 4，和PopP 2，一种来自Ralstonia sp.的乙酰转移酶。RPS 4是典型的TIR-NB-LRR R蛋白，但RRS 1 TIR-NB-LRR R蛋白还携带WRKY DNA结合结构域，其充当检测AvrRps 4和PopP 2的存在和/或活性的“诱饵（威廉姆斯等人，2014年; 10.1126/science.1247357 Sarris等人，2015年; 10.1016/j.cell.2015.04.024）。RPS 4/RRS 1激活防御导致快速诱导~40个ETI基因，包括水杨酸生物合成基因，其他防御酶和转录调节因子（Sohn等，2014 10.1371/journal.pgen.1004655）。本研究的目的是了解RPS 4/RRS 1如何激活拟南芥中这40个共调节的ETI基因。学生将测试激活后，RPS 4/RRS 1是否与ETI防御过程中诱导的基因的染色质状态相关并改变染色质状态。该项目将确定在激活后，在染色质中的变化在ETI诱导的基因，并分析与防御基因启动子相关的转录因子。

Plant disease resistance (R) proteins enable plants to detect specific pathogen effector molecules, and then activate defence, yet mechanisms of defence activation upon R protein activation (Effector-Triggered Immunity, or ETI) are poorly understood. Arabidopsis RPS4 and RRS1 resistance genes act together to detect two different bacterial effector proteins, AvrRps4 from Pseudomonas sp., and PopP2, an acetyltransferase, from Ralstonia sp.. RPS4 is a typical TIR-NB-LRR R protein, but the RRS1 TIR-NB-LRR R protein also carries a WRKY DNA binding domain, that acts as a "bait" that detects the presence and/or activity of AvrRps4 and PopP2 (Williams et al 2014; 10.1126/science.1247357 Sarris et al 2015; 10.1016/j.cell.2015.04.024).Activation of defence by RPS4/RRS1 results in rapid induction of ~40 ETI genes, including genes for salicylic acid biosynthesis, other defence enzymes and transcription regulators (Sohn et al, 2014 10.1371/journal.pgen.1004655). The goal of the studentship is to understand how RPS4/RRS1 activates these ~40 coregulated ETI genes in Arabidopsis upon effector perception. The student will test if upon activation, RPS4/RRS1 associates with and changes the chromatin state of genes that are induced during ETI defence. The project will define changes in chromatin at ETI-induced genes upon activation, and analyse transcription factors that associate with defence gene promoters.