由茄科雷尔氏菌引起的青枯病是危害极大的植物细菌性病害。Ⅲ型分泌系统效应蛋白对该菌的侵染和定殖起着关键作用。我们前期研究发现，RipN在各茄科雷尔氏菌菌株中高度保守且是唯一被证实具有Nudix水解酶活性的植物病原细菌效应蛋白。其能抑制植物免疫，以ADP核糖为最适酶活底物并以富含甘氨酸RNA结合蛋白2（GRP2）为互作靶点，但它抑制免疫的分子机制尚不明确。已有研究表明GRP2参与免疫且具有潜在的ADPr修饰。我们推测，RipN通过去除GRP2的ADPr修饰以干扰GRP2介导的免疫调控。本项目拟采用双分子荧光互补和酵母双杂交方法，明确互作发生的亚细胞位点和关键蛋白区段；利用质谱、点突变和抗体检测方法，解析RipN对GRP2相关修饰影响；利用组学、转录水平及蛋白质含量检测方法，阐明RipN所干扰的免疫组分和通路。本项目完成，可揭示RipN抑制植物免疫的分子机制，同时可望为开发抗病药物提供新的靶点。

Bacterial wilt is one of the most destructive plant bacterial diseases. Ralstonia solanacearum is the causative agent of bacterial wilt, and the type Ⅲ effectors are indispensable for its pathogenesis of plant hosts. In previous studies, we found that RipN is a highly conserved type Ⅲ effector within Ralstonia solanacearum species complex and is the only effector of plant pathogenic bacteria that has been proved to have the activity of Nudix hydrolase. We also have provided evidences that RipN could down regulate plant immunity, takes ADP-ribose as the optimal substrate of Nudix hydrolase activity and takes plant Glycine-rich RNA-binding protein2 (GRP2) as the target protein. However, the molecular mechanism of RipN inhibiting the plant immunity remains still unclear. It has been shown that GRP2 is an immune-related protein with potential ADPr modification. We hypothesized that RipN interferes the plant immunity by removing the ADPr related modification of GRP2. To test this hypothesis, the bimolecular fluorescence complementation and yeast-two-hybrid methods will be used to determine the subcellular sites and key motif of RipN-GRP2 interaction; Using mass spectrometry detection and amino acid site-specific mutation assays, combining with the detection by specific antibody, the interference mechanism of the ADPr related modification of GRP2 by RipN will be investigated; The immune components or pathways of plant immunity interfered by RipN will be investigated by using transcriptome and proteomics, combining with qRT-PCR and specific protein detection methods. This research will reveal the molecular mechanism of RipN inhibiting the plant immunity. These results will also provide new clues for studying the chemical inhibitors for disease control.