Progress on the biosynthesis and signal transduction of phytohormone salicylic acid.

The phenolic phytohormone salicylic acid (SA) is widely produced in plants, and is a key player in many processes of plant physiology, especially in plant immunity. During pathogen infection, SA is accumulated and the SA signaling pathway is activated to induce the expression of defense-related genes. Recently, a series of SA-related studies have been published. These researches filled gaps in the two SA biosynthesis pathways: the isochorismate synthase (ICS) pathway and the phenylalanine ammonia-lyase (PAL) pathway. The NPR1 (nonexpresser of PR genes 1) and its paralogs, NPR3 and NPR4, were identified as SA receptors. The effect of type II TGAs (TGACG-binding factor) on SA downstream genes was shown to depend on the SA receptor they interacted with. This review will systematically introduce the progress on SA biosynthesis and signal transduction, aiming to provide a theoretical reference for in-depth study of SA regulation on plant development and defense responses.植物激素水杨酸(salicylic acid,SA)是广泛存在于植物体中的小分子酚类物质,参与植物多种生理过程,特别是在植物免疫中发挥重要功能。植物免疫过程中体内SA大量合成,SA信号通路被激活从而诱导抗病相关基因表达。近年来,随着研究的不断深入,SA生物合成和信号转导都取得一系列重要进展：进一步完善了SA生物合成的异分支酸合酶(isochorismate synthase, ICS)和苯丙氨酸解氨酶(phenylalanine ammonia-lyase, PAL)途径;明确了NPR1 (nonexpresser of PR genes 1)和其同源蛋白NPR3、NPR4是植物接收SA的受体;发现II类TGA (TGACG-binding factor)转录因子通过与不同SA受体互作激活或抑制下游基因表达等。本文系统介绍了SA生物合成和信号转导领域的相关进展,以期为深入研究SA调控植物生长发育和环境胁迫响应提供理论参考。.