水杨酸类药物是世界医药史上经典的解热镇痛药，同时水杨酸也是一种重要的植物激素，在植物的先天免疫中发挥核心作用。然而很长时间以来，植物感知水杨酸的精确分子机制，以及水杨酸受体蛋白却一直没有研究清楚。尽管有多个水杨酸结合蛋白被鉴定出来，但遗传学及其他证据陆续证明这些蛋白均不是水杨酸的受体。2012年，两个研究组先后提出了两种不同、但又并不完全排斥的植物感知水杨酸的模型，在这两个模型中，NPR3/4，以及NPR1蛋白分别被鉴定为水杨酸的受体蛋白。为了阐明植物识别水杨酸的分子机制、解决目前关于水杨酸受体的争议，本项目拟对上述水杨酸受体蛋白（NPR1/3/4）的结构与功能进行研究，通过解析其结构并结合体内和体外实验，阐明植物感知水杨酸的精确机制。这些研究将在蛋白质结构水平上揭示水杨酸结合其受体蛋白并激活植物免疫反应的分子机制，为发展提高农作物抗性的方法奠定理论基础。

Salicylic acid (SA)-like compounds have been the most classical medicines which relieve pain and fever during the world medical history, and as an important plant hormone, SA plays a central role in plant innate immunity. However, it still remains unknown how SA is sensed by plants and the identity of the SA receptors. Although several SA-binding proteins have been identified using biochemical approaches, genetic and other evidence indicated that they are not the bona fide SA receptors. In 2012, two groups raised two different, but not exclusive models of SA perception by plants, in which NPR3/4 and NPR1 were identified to be the SA receptors, respectively. To illustrate the molecular mechanism of plant perception of SA and clarify the controversy over SA receptors, this project will conduct the structural and functional studies into the potential SA receptors NPR1/3/4. Through the protein structures, in vitro and in vivo experiments, the project will illustrate the precise mechanisms underlying plant perception of SA. These studies will reveal the molecular mechanism how SA binds to its receptors and activates plant immune system through the structural information, and provide the theoretical basis for developing approaches to improve the resistance of crops.