非寄主种子/根分泌物中抑制性信号分子挖掘及其对大豆疫霉的信号作用机制

大豆疫霉(Ps)为重要土传病原卵菌，仅侵染大豆。普遍认为异黄酮是Ps的寄主专化性信号分子，氨基酸和糖对Ps也有信号作用，但却不能解释为什么Ps不侵染同样含有这些物质的菜豆，也不侵染轮作玉米。我们发现菜豆种子分泌物溶解、玉米种子分泌物排斥Ps，说明非寄主分泌物中存在抑制性信号分子，但缺乏对抑制性信号分子的系统研究，限制了非寄主抗病性的应用。本项目拟明确非寄主种子/根分泌物中抑制性信号分子种类及浓度，并研究Ps的应答机制。1）充分挖掘、鉴定非寄主种子/根分泌物中的抑制性信号分子，明确其对Ps侵染前发育行为的抑制作用和对Ps的特异性；2）从病菌发育行为和受体生化特征层面分析Ps的应答机制。通过研究Ps与非寄主分泌物中抑制性信号分子的关系，阐明抑制性信号分子对Ps的抑菌机制，揭示其对Ps建立寄主专化性的贡献，为设计高效卵菌药剂，实现Ps根际行为预测和调节提供依据，为土传病害防治开辟一条新路。

Phytophthora sojae (Ps) is an important soilborne pathogen that only infects soybeans. It is generally believed that isoflavones are host-specific signaling molecules for Ps infection of soybeans, and amino acids and sugars also be found as nonhost-specific signaling molecules for Ps. But it is hardly to explain why Ps does not infect common bean and maize with the same components. We found that the seed exudates of common bean lyzes and that of maize repels Ps, which suggests that there are inhibitory signaling molecules in nonhost exudates, but there is a lack of systematic study of inhibitory signaling molecules, which restricts application of nonhost disease resistance. This project aims to study the response mechanism of Ps to the inhibitory signaling molecules on the basis of identifying the types and concentrations of inhibitory signaling molecules in nonhost seed/root exudates. 1) Fully dig and identify the inhibitory signaling molecules in the nonhost seed/root exudates and determine their inhibitory effect on developmental behavior before infection and the specificity on Ps; 2) Analysis of the mechanism of Ps response at the levels of both developmental behavior and biochemical characteristics of receptor to the inhibitory signaling molecules. We will provide a basis for designing high-efficiency oomycetescide and realize the prediction and regulation of Ps behavior in rhizosphere by studying the relationship between Ps and the inhibitory signaling molecules in nonhost seed/root exudates, clarifying the antimicrobial mechanism of inhibitory signaling molecules against Ps, and reveal its contribution to the establishment of host specialization in Ps. It will open a new way for the control of soilborne diseases of plants.