Investigation of plant immunity activated by enforced nuclear localization of EDS1 (Enhanced Disease Susceptibility1) in Arabidopsis

核苷酸结合富亮氨酸重复序列（NLR）型免疫受体可以直接或间接识别病原微生物分泌到宿主细胞质中的效应分子。效应物识别和NLR激活诱导了快速的耐药反应，有效地限制了微生物的生长。在植物中，nlr根据其n端卷曲线圈（CC， CNL）或Toll/白细胞介素1样受体（TIR, TNLs）结构域进行分类。CC和TIR结构域被认为在信号起始中起作用，但激活nlr下游的信号成分以及细胞核内的转录重编程如何实现在很大程度上仍然未知。有趣的是，tnl在功能上依赖于核细胞质蛋白增强疾病易感性1 （EDS1）。我们发现EDS1-YFPNLS融合的表达，强制核定位，可以导致转基因拟南芥中温度依赖性的自身免疫诱导。EDS1-YFPNLS高水平表达融合蛋白，在22°C下导致幼苗死亡，用于遗传筛选。我们分离了大约50个抑制eds1 - yfpnls诱导的自身免疫的濒死体验（nde）突变体。对nde1等位基因的分析发现，DM2h是TNL RPP1的类似物，是自身免疫的中介。DM2位点在不同拟南芥种质间具有高度多态性，是导致杂交不亲和性（HI）的主要原因。一个nde1等位基因在不同遗传背景下的渗入，首次为直立兰（Landsberg erecta） DM2基因的个体意义提供了遗传证据。我们发现DM2hLer不仅在两种异位诱导的自身免疫中是必需的，而且在由DM2Ler与来自中亚拟南芥的SRF3等位基因形式的有害上位相互作用引起的HI中也是必需的。在这个项目中，我们想要鉴定和表征额外的NDE基因座，以了解由强制核EDS1定位诱导的自身免疫，并鉴定TNL信号的组成部分。此外，我们想要分析DM2Ler相似物，以了解由结构不同的诱导剂激活的自身免疫如何收敛到单个NLR上，以及DM2Ler相似物如何促进植物免疫。

Nucleotide-binding leucine-rich repeat (NLR) -type immune receptors can, directly or indirectly, recognize effector molecules secreted into the host cell cytoplasm by pathogenic microbes. Effector recognition and NLR activation induce a rapid resistance response efficiently restricting microbial growth. In plants, NLRs are classified by their N-terminal coiled-coil (CC, CNL) or Toll/interleukin 1-like receptor (TIR, TNLs) domains. CC and TIR domains are assumed to function in signal initiation, but signaling components downstream of activated NLRs and how transcriptional reprogramming inside nuclei is achieved remain largely unknown. Interestingly, TNLs are functionally dependent on the nucleo-cytoplasmic protein Enhanced Disease Sucpetibility1 (EDS1). We discovered that expression of an EDS1-YFPNLS fusion, for enforced nuclear localization, can lead to temperature-dependent induction of autoimmunity in transgenic Arabidopsis. An EDS1-YFPNLS line expressing the fusion protein to high levels and causing seedling lethality at 22°C, was used in a genetic screen. Approximately 50 near death experience (nde) mutants suppressing EDS1-YFPNLS-induced autoimmunity were isolated. Analysis of nde1 alleles identified DM2h, a paralog of the TNL RPP1, as mediator of autoimmunity. The DM2 locus is highly polymorphic between different Arabidopsis accessions, and is causal in several resolved cases of hybrid incompatibility (HI). The introgression of an nde1 allele into different genetic backgrounds provided first genetic evidence on the significance of an individual DM2 gene from accession Landsberg erecta (Ler). We show that DM2hLer is not only essential in two cases of ectopically-induced autoimmunity, but also in HI caused by deleterious epistatic interactions of DM2Ler with SRF3 allelic forms from Central Asian Arabidopsis accessions. In this project, we want to identify and characterize additional NDE loci to understand autoimmunity induced by enforced nuclear EDS1 localization and to identify components of TNL signaling. Furthermore, we want to analyze DM2Ler paralogs to understand how autoimmunity activated by structurally different inducers converges onto a single NLR and how DM2Ler paralogs contribute to plant immunity.