拟南芥组蛋白H3K9去甲基化酶JMJ27调控虫害响应的分子机制研究

Insect pests are important factors causing great loss in agricultural production. Improving crop anti-herbivore resistance is an idea method for controlling crop pests and reducing pesticide application. Various environmental stress, including insect pests, can induce the change of epigenetic modification in plants, but the mechanism of epigenetic regulation of anti-herbivore response is still unclear. In our previous work, we found that the H3K9me1/2 demethylase, JMJ27, negatively regulated resistance to the chewing generalist insect Spodoptera litura in Arabidopsis thaliana, and JMJ27 also negatively regulated the response to jasmonic acid signaling. In this study, the mutants and transgenic materials will be used to further clarify the regulatory of JMJ27 on anti-herbivore resistance in plants. The physiological and biochemical basis of JMJ27 regulation in plant anti-herbivore responses will be determined by analysis of defense-related enzymatic activities and the defense-related chemicals. The directed target genes of JMJ27 in regulating anti-herbivore response of plants will be identified by transcriptome sequencing, chromatin immunoprecipitation-sequencing (ChIP-seq) technology and genetic approaches, so as to reveal the molecular mechanism of JMJ27 in regulating anti-herbivore response in plants. As a result, this research will lay a foundation for understanding the epigenetic molecular regulation mechanism of anti-herbivore resistance in plants.

虫害是造成农业减产的重要原因。提高作物自身对害虫的抗性是控制农作物虫害和减少农药施用的理想选择。包括虫害在内的多种环境胁迫均可引起植物表观修饰的改变，但是植物对虫害响应的表观调控机制尚不清楚。申请人在前期工作中发现H3K9me1/2去甲基化酶JMJ27负调控拟南芥对咀嚼式广食性害虫斜纹夜蛾的抗性，并且负调控茉莉酸信号响应。本研究将利用拟南芥突变体和转基因材料进一步明确JMJ27对植物抗虫防御反应的调控作用；通过对抗虫酶活性、抗虫物质含量的测定明确JMJ27负调控植物虫害的生理生化机制；利用转录组测序、染色质免疫共沉淀测序技术和遗传学方法鉴定JMJ27在调控植物响应虫害的关键靶基因，从而揭示JMJ27调控拟南芥抗虫响应的分子机理。研究成果将为阐明植物自身抗虫的表观遗传学分子调控机制奠定基础。

虫害是造成农业减产的重要原因。提高作物自身对害虫的抗性是控制农作物虫害和减少农药施用的理想选择。包括虫害在内的多种环境胁迫均可引起植物表观修饰的改变，但是植物对虫害响应的表观调控机制尚不清楚。通过本项目的研究，我们发现H3K9me1/2去甲基化酶JMJ27负调控拟南芥对咀嚼式广食性害虫斜纹夜蛾的抗性，并且其调控依赖于JMJ27的去甲基化酶活性。转录和蛋白水平检测显示，植物通过抑制负调控因子JMJ27的表达来响应虫子的取食。转录组分析表明JMJ27在虫害条件下激活的基因主要参与免疫响应、胁迫响应、水杨酸信号途径、JA信号途径等多个免疫相关过程。通过qPCR、ChIP-qPCR等实验表明，虫害条件下JMJ27通过影响H3K9me2修饰而抑制VSP1、VSP2、JAL23等JA相关基因的表达。另一方面，JMJ27直接去除SA相关基因RP1、PR5的H3K9me2而促进基因表达对虫害的响应，说明JMJ27通过直接或者间接的方式来减少或增加H3K9me2修饰来促进SA而抑制JA信号通路，从而负调控植物对虫害的响应。此外，我们发现wrky54-1和wrky70-1突变体抑制斜纹夜蛾取食后的体重增长，同时JMJ27能够直接去除WRKY54和WRKY70的H3K9me2修饰来促进基因表达，说明JMJ27部分通过促进WRKY54、WRKY70的表达来负调控虫害响应。该研究成果解析了H3K9me2修饰在模式植物拟南芥中的虫害防御响应机制，为进一步深入揭示组蛋白甲基化修饰在调控植物抗虫的表观遗传分子机制奠定基础，为作物抗虫育种提供理论指导。