水稻泛素连接酶PEL1介导的稻瘟病抗病机制研究

The rice blast, caused by the fungal pathogens Magnaporthe oryzae, is one of the major factor limiting rice productivity and it’s urgent to developing new rice varieties based on resistance molecular mechanism. The ubiquitin /26S proteasome is an important mechanism that plants used to response to biotic stresses. Among them, E3 ubiquitin ligases have unique specificity in recognizing substrates. Piz-t is a R gene with broad-spectrum resistance to rice blast without yield penalty, and it is widely used in the rice breeding. A thorough understanding of Piz-t-mediated blast resistant mechanism is essential for breeding rice varieties using Piz-t gene. Previous, we used the IP-MS (Immunoprecipitation-Mass Spectrometry) to identify the interactors of Piz-t and a RING-finger E3 liagse PEL1 (Piz-t interacting E3 ligase 1) was selected as the candidate. Expression pattern and transgenic rice analysis results indicated that PEL1 might involve in the defense response to rice blast. In this project, we will focus on the regulation of PEL1 on Piz-t, confirm the function of PEL1 in the rice-M. oryzae interaction, and elucidate the mechanism of PEL1 in the immunity response. Our results will provide theoretical basis and gene resource for improving disease resistance in rice breeding.

稻瘟病是水稻高产、稳产的重要限制因子，解析水稻抗稻瘟病分子机制对培育抗病新品种具有重要指导意义。泛素/26S蛋白酶体途径在植物响应生物胁迫过程中发挥着重要作用，其中泛素连接酶E3决定了对底物蛋白的特异性选择。Piz-t是一个广谱抗稻瘟病基因，在抗病育种中具有重要的应用价值。解析Piz-t的抗病机制对生产上更好利用Piz-t抗病基因具有重要意义。本项目前期筛选到Piz-t的一个RING-finger泛素连接酶E3类型的互作蛋白PEL1（Piz-t interacting E3 ligase 1）。表达模式分析和转基因材料分析结果初步显示，PEL1基因可能参与了水稻对稻瘟菌的抗病反应过程。本项目将进一步研究PEL1与Piz-t互作及调控模式，验证PEL1在水稻抗稻瘟病过程中的生物学功能，深入解析PEL1参与水稻PTI和ETI反应的分子机制，为水稻抗病遗传改良提供理论依据。

稻瘟病是水稻高产、稳产的重要限制因子，解析水稻抗稻瘟病的分子机制对水稻抗病遗传改良具有重要的指导意义。Piz-t是一个广谱抗稻瘟病基因，目前在我国部分省份应用广泛。基于前期筛选到的Piz-t的一个RING-finger泛素连接酶E3类型的互作蛋白PEL1（Piz-t interacting E3 ligase 1）。本研究利用酵母双杂交（yeast-two hybrid, Y2H）、pull-down和免疫共沉淀（Co-immunoprecipitation, Co-IP）实验验证了PEL1可以特异性结合Piz-t的NT和NBS结构域；进一步验证了PEL1具有E3泛素连接酶活性并能够对Piz-t的NT和NBS结构域进行泛素化修饰、且能够促进Piz-t和AvrPiz-t降解的生化功能；本项目通过构建PEL1在NPB和Piz-t背景下的过表达敲除转基因材料，结合抗病表型鉴定，明确了PEL1通过促进Piz-t的降解进而负调控水稻对稻瘟菌防御反应的过程。研究成果明确了PEL1在水稻与稻瘟菌互作中的生物学功能，初步阐明了泛素/26S蛋白酶体途径对R蛋白的调控机制，为水稻抗病遗传改良提供了理论依据。