水稻叶绿体铁氧还蛋白介导免疫反应的分子机理研究

Ferredoxins (Fds), the main distributors for transferring electrons to various acceptor systems in the chloroplast, contribute to redox regulation and antioxidant defense in plants. Although the function of Fd in plant immunity is still unclear, it has been found that expression of Fd-like protein from sweet peper in rice can enhance the resistance to rice pathogen. In addition, our recent study showes that Arabidopsis Fd2 plays an important role in the immune responses to hemibiotrophic and biotrophic pathogens infection. Taken together, these results imply that Fd2 is an important component involved in plant immunity. In this project, we will determine the functions of rice Fd proteins in innate immunity. First, Osfd mutants, generated by CRISPR, will be inoculated with various rice virulent pathogens. The contents of SA and JA will be analyzed in wild type and the mutants without and with infection to investigate the roles of OsFds in regulating defense hormones accumulation. Second, we will determine the function of OsFds in rice PTI and ETI. Third, OsFd-interating proteins will be identified by biochemical assays, whose functions in immunity will also be further studied. Through all the studies mentioned above, a better understanding of the potential roles of OsFds in rice immune responses will provide us new knowledge and strategies for rice disease resistance.

植物叶绿体中的铁氧还蛋白Fd参与光合反应电子传递且调控细胞内氧化还原状态。虽然Fd在植物免疫反应中的功能尚不明确，但已有研究表明在水稻中异源表达Fd的类似蛋白可以提高水稻对病原菌的抗性。我们最近发现拟南芥Fd2在对活体/半活体营养型病原菌的免疫反应中发挥重要作用。本研究旨在解析水稻自身叶绿体Fd蛋白在免疫反应中的功能。首先，我们将通过CRISPR技术敲除水稻中Fd2的同源基因，检测突变体对不同病原菌的抗性。通过测定水稻fd突变体中的的水杨酸和茉莉酸的含量以及标记基因的表达来研究OsFd对于抗病激素合成的调控。其次，本项目将确定OsFd对水稻PTI及ETI介导抗病反应的调节作用。此外，我们还将利用生化方法鉴定OsFd的互作蛋白，并进一步研究该互作蛋白的免疫功能。以上关于OsFd参与水稻抗病网络的机理研究将拓展我们对植物Fd蛋白调控免疫反应的认知，并为培育水稻广谱持久抗病品种提供新思路。

水稻是我国主要粮食作物之一，而稻瘟病作为水稻最主要病害，每年造成巨大的稻米产量损失，严重威胁我国粮食安全。克隆水稻抗稻瘟病基因，并解析其调控的抗病反应信号通路，对水稻抗病育种具有重要的指导意义。本人前期研究表明，叶绿体定位的铁氧还蛋白Fd2对拟南芥基础防御反应和体内抗病激素水平起到重要的调控作用。然而水稻中，对于铁氧还蛋白在抗病反应中的功能至今未见报道。该项目利用遗传学、生物化学、细胞生物学等研究方法，对水稻中叶绿体定位的铁氧还蛋白OsFd2在水稻生长过程以及抗稻瘟病免疫反应中的重要调控作用进行了深入研究。所得研究结果阐明了，OsFd2能够抑制水稻体内活性氧和抗病激素的积累，同时其在体内的表达水平也受到SnRK1激酶复合体的负调控。