拟南芥锌指转录因子SRG1在植物免疫中介导一氧化氮调控转录的机制研究

Phytopathogens cause serious reductions of crop yields and are a threat to food security. Thus, it is important to investigate the mechanisms of plant disease resistance. Nitric oxide (NO), is an important gaseous signal molecule, widely involved in plant immunity by orchestrating defence gene expression. However, the molecular mechanism(s) of NO mediated transcriptional regulation remain unclear. This project aims to uncover how NO controls defence gene expression in plant immunity. To end this, we have identified a zinc finger-containing transcription factor, SRG1, by transcriptome sequencing and associated genetic analysis. The absence of SRG1 function compromised plant immunity. Further, SRG1 was found to be directly S-nitrosylated by NO and this redox-based modification controlled the binding of SRG1 to target DNA cis-elements. We will employ multiple methods to investigate how NO regulates SRG1 transcriptional activity and identify SRG1 target genes. Subsequently, we will explore the biological consequences of reprogramming gene expression by S-nitrosylation of SRG1 during plant immunity. This study will be essential to understand the mechanism of NO-mediated transcriptional regulation and we anticipate these insights will reveal novel strategies to breeding pathogen resistance.

病虫害是限制农业生产的重要因素，严重影响农作物的产量，因此研究植物抗病机理具有重要的科学和现实意义。有研究表明一氧化氮（Nitric Oxide，NO）通过调控基因表达参与植物的抗病反应；但是，当前对植物中NO调控基因表达的分子机制还不清楚。本项目将围绕NO如何在转录水平调控植物免疫这一科学问题展开深入研究。前期实验已利用转录组测序和遗传学分析筛选出一个在植物免疫中受NO调控的基因SRG1，SRG1基因缺失后使植物更易感病。SRG1编码一个含有锌指结构的转录因子，NO可在蛋白翻译后水平对SRG1进行S-亚硝基化修饰。本项目拟通过多种途径探索NO对SRG1的修饰及该修饰对SRG1转录活性的影响，并进一步挖掘SRG1的靶标基因，解析NO通过SRG1对靶标基因的表达进行调控的生物学效应，揭示植物免疫中NO调控基因表达的分子机制，为提高作物抗病性的遗传改良提供理论基础。

一氧化氮（Nitric Oxide，NO）是一种气体激素，可以通过调节基因表达以调控植物的抗病反应；但是，当前对植物中NO调控基因表达的分子机制还不清楚。本研究结合生物化学与分子生物学、遗传学及植物病理学等相关技术，分析了一氧化氮通过调控SRG1的活性实现在转录水平调控的机制。SRG1在植物免疫过程中发挥重要功能，SRG1编码一个转录抑制因子，可与共抑制因子TOPLESS互作，并可以与自身启动子区域结合来调节自身表达水平。NO可以促进SRG1的基因表达，并且随着NO水平不断积累，其可以对SRG1蛋白进行S-亚硝基化修饰，S-亚硝基化修饰的SRG1与启动子DNA基序的结合能力降低，并且转录抑制活性受到影响，从而导致包括SRG1自身在内的SRG1靶标基因表达水平发生改变，从而达到反馈调节植物免疫信号的目的。研究还发现，NO对SRG1进行亚硝基化修饰的半胱氨酸位于锌指结构域内，该氨基酸具有一定保守性，这为将来的抗病分子育种提供了新的候选靶标。