水稻类受体激酶基因SBRR1调控水稻纹枯病抗性的作用机理研究

Sheath blight (SB) poses a great threat to the rice grain yield as one of the most serious rice diseases. Receptor like kinases play important roles in plant defense responses to disease. However, in the study of rice SB resistance, receptor like kinases have not been reported. In our previous studies, a rice receptor like kinases gene SBRR1 induced by necrotrophic pathogens Rhizoctonia solani had been isolated. Through identification of resistance of the SBRR1 loss-of-function mutant and SBRR1-RNAi transgenic lines to SB, we have demonstrated that SBRR1 positively regulates resistance to SB.. Based on the above studies, in this project we will 1) analyze the expression pattern and biochemical characteristics of SBRR1; and 2) perform identification of SB resistance in the SBRR1 loss-of-function mutant, overexpression and RNAi lines, and measure the PTI- and physiological pathology-related indexes, and then investigation of main agronomic traits of those materials to explore the regulation mechanism of SBRR1 on the resistance to SB and its breeding value, and 3) identify interaction proteins of SBRR1 via analyzing the interaction between SBRR1 and known receptor like kinases proteins related to disease-resistance and yeast two hybrid screening, and research the role of interaction proteins in SBRR1-mediated signaling pathway of rice sheath blight resistance, and then preliminarily analyze its signaling pathway that regulate the resistance to SB. The proposed project will enrich the knowledge of the molecular mechanism of resistance to rice SB, which will provide the theories basis for establishing a new strategy to prevent and control this disease.

纹枯病是水稻最严重的病害之一，对水稻产量构成巨大的威胁。类受体激酶在植物抗病防御反应中发挥着重要的作用，但在水稻纹枯病抗性研究中还未见报道。前期研究中，我们分离了1个受纹枯病菌显著诱导表达的类受体激酶基因SBRR1，对SBRR1的功能缺失突变体和RNAi植株进行了纹枯病抗性鉴定，证实SBRR1正调控水稻对纹枯病的抗性。.在此基础上，本项目将：1）分析其表达模式和生化特性；2）对其突变体、过表达和RNAi植株进行纹枯病抗性鉴定，测定纹枯菌接种前后PTI反应、生理病理学相关指标，同时考察农艺性状，探讨其调控水稻纹枯病抗性的作用机制及育种价值；3）通过分析其与已知抗病相关类受体激酶的互作和酵母双杂交筛库鉴定其互作蛋白，并研究互作蛋白在其介导的水稻抗纹枯病信号途径中的作用，初步解析其调控水稻纹枯病抗性的信号途径。结果将丰富水稻抗纹枯病分子机理的相关知识，为建立水稻纹枯病防治新策略提供理论依据。

纹枯病是水稻最严重的病害之一，由于抗病基因资源匮乏及抗病机理研究滞后，抗纹枯病育种一直进展缓慢。类受体激酶在植物抗病防御反应中发挥着重要作用，目前在水稻纹枯病的抗性研究中还未见该类基因的相关报道。本项目通过全基因组关联分析（GWAS）在水稻自然品种中克隆到一个具有明显应用前景的抗纹枯病数量基因SBRR1 (sheath blight-related RLK 1)，其编码类受体激酶，敲除和过表达SBRR1分别增强和减弱纹枯病抗性。qRT-PCR结果表明SBRR1主要在叶鞘和叶片中表达；亚细胞定位结果表明SBRR1蛋白定位于细胞膜；ROS迸发检测和PTI标志基因定量结果表明SBRR1参与调控水稻PTI反应；酵母双杂交、Co-IP、BiFC、Pull-down体内体外试验证实SBRR1与锚定蛋白SIP1 (SBRR1 interaction protein 1)互作，基因敲除和过表达遗传试验表明SIP1正向调控纹枯病抗性；转录组分析及几丁质酶活性测定结果证明SBRR1和SIP1通过影响几丁质酶活性来调控水稻纹枯病抗性。以上结果丰富了水稻抗纹枯病分子机理的相关知识，为建立水稻纹枯病防治新策略提供理论基础。