RLP- and RLK-mediated innate immune responses in Arabidopsis and tomato triggered by pathogen-associated molecular patterns (PAMPs) and avirulence factors (Avrs) (ERA-PG 002)

农作物不断受到由微生物病原体引起的毁灭性疾病的威胁。植物具有先天免疫系统，通过一般病原体相关的分子模式或特定病原体衍生的无毒因子识别微生物后被激活。两种类型的细胞外植物质膜受体（受体样蛋白（RLPs）和受体样激酶（RLKs））在细胞间隙感知PAMPs和Avrs并启动免疫应答。这两种类型都含有胞外富亮氨酸重复序列（eLRR），监测特定病原体分子的存在。对于rlp，这些eLRRs锚定在质膜上，仅携带缺乏明显信号基的短细胞质结构域。相反，RLKs含有一个细胞质激酶结构域，用于下游信号传导。拟南芥和番茄是典型的模式植物。拟南芥的基因组序列已经获得，而番茄的基因组序列将在2-3年内获得。在番茄中，avr感知的rlp包含了具有良好特征的黄枝孢杆菌和大丽花黄萎病抗性蛋白。在拟南芥中，RLP RPP27识别卵菌透明膜孢子菌寄生。参与PAMP感知的番茄rlp包括识别绿色木霉的LeEix蛋白。参与Avr和PAMP识别的RLKs包括水稻Xa21，识别米黄单胞菌，拟南芥FLS2和EFR，识别PAMP鞭毛蛋白和EF-Tu，以及拟南芥ERECTA，这是抵抗各种病原体所需的RLKs。在这一建议中，我们旨在研究rlp和RLKs在植物物种番茄和拟南芥中通过细胞外PAMPs和Avrs感知微生物病原体的作用。此外，我们想剖析下游防御信号通路在两个植物物种激活病原体感知。不同的项目合作伙伴将使用遗传、蛋白质组学和转录组学方法研究这些机制。

Crop plants are continuously threatened by devastating diseases caused by microbial pathogens. Plants possess an innate immune system that is activated after recognition of microbes through general pathogen-associated molecular patterns or specific pathogen-derived avirulence factors. Two types of extracellular plant plasma membrane receptors (receptor-like proteins (RLPs) and receptor-like kinases (RLKs)) perceive PAMPs and Avrs in the intercellular space and initiate an immune response. Both types contain extracellular leucine-rich repeats (eLRR) that monitor the presence of specific pathogen molecules. For RLPs, these eLRRs are anchored in the plasma membrane and carry only a short cytoplasmic domain that lacks obvious signalling motifs. In contrast, RLKs contain a cytoplasmic kinase domain for downstream signalling. Arabidopsis and tomato are well-characterized model plants. The genome sequence of Arabidopsis is available whereas that of tomato will become available within 2-3 years. In tomato, Avr-perceiving RLPs encompass the well-characterized Cladosporium fulvum and the Verticillium dahliae resistance proteins. In Arabidopsis the RLP RPP27 recognizes the oomycete Hyaloperonospora parasitica. Tomato RLPs involved in PAMP perception include LeEix proteins that recognize Trichoderma viride. RLKs involved in Avr and PAMP recognition are rice Xa21, recognizing Xanthomonas oryzae, Arabidopsis FLS2 and EFR, recognizing the PAMPs flagellin and EF-Tu, and Arabidopsis ERECTA that is required for resistance against various pathogens. In this proposal we aim to investigate the role of RLPs and RLKs in the perception of microbial pathogens through extracellular PAMPs and Avrs in the plant species tomato and Arabidopsis. Furthermore we want to dissect downstream defense signalling pathways in the two plant species activated upon pathogen perception. The various project partners will study these mechanisms using genetic, proteomics and transcriptomics approaches.