水稻cZ合成基因OsIPT9的抗虫功能和分子机理研究

Rice (Oryza sativa L.), the most important food crop in China. The brown planthopper (BPH) has become the most destructive and a serious threat to the rice production in Asia. Breeding the resistant varieties with improved host resistance is the most effective and ecosystem-friendly strategy of BPH biological management. The brown planthopper resistance gene Bph6 is a novel and broad-spectrum insect resistance gene, positive regulates the cytokinin biosynthesis to against BPH, which has important application value in breeding of brown planthopper resistance. cZ (cis-zeatin) is the most abundant cytokinin in rice. However, the study on the growth and development and plant immune function of cZ is not clear. OsIPT9 and OsIPT10 are rate-limiting enzymes for cZ biosynthesis in rice. In previous studies, we found that OsIPT9 participates in Bph6-mediated resistance and the downstream response factor OsRR11 interacted with OsCPS2, an enzyme for diterpenoid phytoalexins biosynthesis in rice. Based on these results, in this project we will further analysis the biological function, biochemical function, insect resistance mechanism of OsIPT9, the interaction and regulatory relationship between BPH6 and OsIPT9, and reveal the molecular mechanism of BPH6 regulating cZ synthesis. We will also clarify the function of OsIPT9 and the regulatory mechanism of OsRR11 on OsCPS2, and elucidate the downstream signal transduction pathway of cZ. The results of this project will provide an important theoretical basis for the study of rice insect resistance mechanism and the interaction between plants and insects, and also provide a realistic basis for Bph6 application in insect-resistant breeding in rice.

水稻是我国最重要的粮食作物，褐飞虱是水稻生产的头号害虫。遏制褐飞虱的发展和危害是保障我国乃至亚洲水稻生产安全的重大需求。水稻抗褐飞虱基因Bph6是一种新型广谱抗虫基因，能正调控细胞分裂素从而发挥抗虫性。cZ是水稻中含量最高的一类细胞分裂素，然而cZ在生长发育和植物免疫功能方面缺乏深入的研究。OsIPT9和OsIPT10的是水稻cZ生物合成的限速酶。我们在前期研究中发现OsIPT9参与Bph6介导的抗性并验证了下游响应因子OsRR11与植保素合成蛋白OsCPS2的互作。本项申请拟在此基础上进一步分析OsIPT9的生物学功能、生化功能、抗虫机理和BPH6对其调控的机理，揭示cZ在抗虫中的分子机理。明确OsRR11对OsCPS2的调控机理，阐明cZ下游信号转导途径。本项目研究结果将为水稻抗虫机理研究以及植物与昆虫的互作提供重要的理论支撑，同时为Bph6在抗褐飞虱育种中的应用提供现实基础。

水稻是我国最重要的粮食作物，褐飞虱是水稻生产的头号害虫。遏制褐飞虱的发展和危害是保障我国乃至亚洲水稻生产安全的重大需求。水稻抗褐飞虱基因Bph6是一种新型广谱抗虫基因，能正调控细胞分裂素从而发挥抗虫性。cZ是水稻中含量最高的一类细胞分裂素，然而cZ在生长发育和植物免疫功能方面缺乏深入的研究。本项目在前期研究的基础上，利用分子生物学、遗传学和生物化学等手段，初步阐明了Bph6调控cZ的分子机理，揭示了cZ介导抗虫的分子机制，获得了一下几个重要结果：1）水稻细胞分裂素合成基因OsIPT9参与了Bph6介导的抗性，其转录和蛋白水平受褐飞虱取食诱导表达; OsIPT9参与水稻cZ生物合成，是水稻cZ合成限速酶。2）发现了BPH6与OsIPT9互作并调控OsIPT9的蛋白表达量升高从而使cZ含量升高的分子机理。3）发现了cZ特异下游响应调控因子OsRR11，初步解析了OsRR11与调控植保素合成基因OsCPS2的启动子区（G/A）GAT(T/C)的保守元件结合从而调控OsCPS2基因表达和植保素合成的分子机理。4）基于课题中取得的研究进展和结果，目前已公开发表标注课题的SCI论文1篇，授权发明专利1项，且后续仍有重要SCI论文和发明专利产生。本项目研究结果将为水稻抗虫机理研究以及植物与昆虫的互作提供重要的理论支撑，同时为Bph6在抗褐飞虱育种中的应用提供现实基础。

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