大豆凝集素受体蛋白激酶抗大豆疫霉菌侵染的作用机理研究

Root rot caused by Phytophthora sojae is one of the destructive diseases in soybean (Glycine max). Upon pathogen infection, membrane-localized immune receptors mediate the first layer of plant innate immunity. However, whether this type of receptors plays a role in Phytophthora resistance is well studied. Our previous work revealed that the membrane-localized receptors – L-type lectin receptor-like kinases (LecRKs) − in Arabidopsis are involved in Phytophthora resistance. In soybean, we found 68 LecRKs, and 36 of these LecRKs are significantly up- or down-regulated upon infection by P. sojae. To further confirm the function of soybean LecRKs in P. sojae resistance, we will transiently silence or overexpress LecRKs in soybean hair roots and perform infection assays with different P. sojae isolates. Furthermore, we will generate transgenic soybean plants expressing LecRKs and test plant defense response against P. sojae. We will also identify LecRK-interacting proteins using co-immunoprecipitation followed by mass spectrometry and analyze how the interacting proteins function in P. sojae resistance. The findings in this project will, on the one hand, provide new insights into how LecRKs mediate Phytophthora resistance and facilitate our understanding on plant resistance against Phytophthora pathogens; on the other hands, provide novel resistance resource for soybean breeding.

大豆疫霉引起的根腐病是大豆生产上的一种毁灭性病害。植物细胞膜上的免疫受体作为抵御病原物侵染的重要防线，其在大豆上如何防御大豆疫霉的侵染目前尚不清楚。申请人前期在拟南芥中发现凝集素受体蛋白激酶（LecRK）作为一类细胞膜受体，参与对疫霉菌的抗病反应。通过生物信息学手段从大豆中鉴定到68个LecRK基因，并通过转录分析筛选到36个与大豆疫霉侵染相关的基因。本项目拟采用大豆根毛瞬时沉默和过表达技术，评价上述基因对大豆疫霉的抗性作用。获得对大豆疫霉具有显著抗病性的基因，并进一步在大豆中进行稳定表达，评价其在抗大豆疫病中的应用潜能。在此基础上，采用免疫共沉淀与质谱技术鉴定LecRK的结合蛋白，解析这些结合蛋白对大豆疫病抗性作用机制。研究结果可揭示LecRK基因对大豆疫病抗病作用的分子机制，有助于进一步阐明植物对疫霉菌的抗病机理并为改良大豆提供新的抗病资源和理论指导。

作物疫病是由疫霉菌引起的一类毁灭性病害，每年导致我国大豆、马铃薯和蔬菜等作物的经济损失高达数百亿元。疫病难防控的根本原因是爆发迅速、传播快。因此，挖掘和利用持久广谱抗性资源对有效控制作物疫病至关重要。细胞膜上的免疫受体通过识别病原物侵染激活植物基础抗性对抵御病原物侵染具有重要作用。本研究通过系统分析大豆凝集素受体蛋白激酶（LecRK）家族，鉴定到65个LecRK基因，通过进化分析发现14个大豆特异性LecRK基因。通过转录组分析确定了大豆LecRK基因在疫霉菌侵染过程中的表达模式。进一步通过大豆遗传转化，鉴定到三个参与大豆-疫霉菌互作的LecRK基因。过表达LecRK基因提高了疫霉菌侵染激活的大豆免疫相关基因的表达，并且提高了大豆对疫霉菌的抗性。对其中两个LecRK互作蛋白及其生物学功能的分析，发现LecRK一方面可与细胞膜上的ATP酶互作参与植物对疫霉菌的识别，另一方面LecRK也作为疫霉菌致病因子的靶标蛋白促进疫霉菌侵染。研究结果初步揭示了大豆LecRK基因在大豆和疫霉菌互作中的作用机制，该研究不仅有助于深入解析作物对疫霉菌基础抗性的调控机制，并且为作物抗病育种提供了新的抗性资源。