JAZ互作蛋白NOT2调控植物抗病反应的分子机理

Jasmonates (JAs), a class of cyclic fatty acid-derived plant hormones, regulate diverse aspects of plant developmental processes and also act as key defense signals upon both abiotic and biotic stresses. Characterization of novel JAZ-interacting proteins is important to further understand the molecular basis of jasmonate action. Interestingly, through exhaustedly screening the Arabidopsis thaliana cDNA library using JAZ proteins (JAZ1 and JAZ9) as bait in the yeast two-hybrid (Y2H) system, we found that JAZ proteins can interact with the core members of the CARBON CATABOLITE REPRESSION4 (CCR4)-NOT complex，namely NOT2s. Our recent study demonstrated that mutation of NOT2s caused decreased resistance to both B. cinerea and A. brassicicola, but increased resistance to Pst DC3000. Expression analysis showed that treatment with MeJA can obviously change the subcellular localization of NOT2 proteins and the expression of the JA marker genes, such as PDF1.2 and Thi2.1, were dramatically repressed in the not2a-1 2b-1 double mutant. These results implied that NOT2s may participate in plant disease responses through interaction with JAZ proteins. Based on these results, we will further determine the biological consequence of JAZ-NOT2 interaction and the JAZ-NOT2 complex regulated downstream target genes, explore the molecular function of NOT2s in the regulation of plant disease resistance response, illustrate the molecular mechanism of plant disease resistance response that controlled by JAZ-NOT2 complex, and finally enrich the JA-mediated disease resistance signaling network.

JA是一类由环状脂肪酸衍生的植物激素，参与调控植物发育和抗病耐逆。鉴定新颖的JAZ互作蛋白对于进一步理解茉莉酸信号转导途径的作用机理具有重要意义。通过酵母双杂交筛选发现JAZs可以与CCR4-NOT复合物中的核心成员NOT2s相互作用。初步研究表明NOT2s突变显著降低了植株对B. cinerea 和A. brassicicola的抗性,但增强了植株对Pst DC3000的抗性。表达分析表明MeJA处理显著改变了NOT2s在细胞中的组织定位，同时NOT2s突变显著抑制了JA标志基因PDF1.2和Thi2.1的表达。这些结果暗示NOT2s可能通过与JAZs互作参与调控植物抗病反应。在此基础上我们将进一步明确JAZ-NOT2蛋白互作的生物学效应及其调控的下游基因，阐明NOT2s在植物抗病反应中的功能，解析JAZ-NOT2复合物调控植物抗病反应的分子生物学机制，进而丰富JA介导的抗病信号网络。

JA是一类由环状脂肪酸衍生的植物激素，参与调控植物发育和抗病耐逆。鉴定新颖的JAZ互作蛋白对于进一步理解茉莉酸信号转导途径的作用机理具有重要意义。在本项目中，通过酵母双杂交筛选发现JAZs可以与CCR4-NOT复合物中的核心成员NOT2s相互作用。研究表明NOT2s突变显著降低了植株对B. cinerea 和A.brassicicola的抗性,但增强了植株对Pst DC3000的抗性。表达分析表明NOT2s突变会显著影响多个抗病相关基因表达，同时MeJA处理可以改变了NOT2s在细胞中的组织定位，且其定位受COI1控制，因此我们推测在正常情况下茉莉酸途径中的转录抑制蛋白JAZs可以抑制NOT2s使其定位于细胞质，而当植物遭受病原菌侵染时，JAZs被降解，从而释放NOT2s并促使其进入细胞核发挥功能。同时通过酵母双杂交筛选发现NOT2s还能与多个与抗病相关的MEDs相互作用。因此我们推测植物遭受病原菌侵染时进入细胞核的NOT2s能与MEDs形成蛋白复合物，并共同调控植物抗病过程。我们将进一步开展工作明确JAZ-NOT2-MED蛋白复合物协同调控植物抗病反应的分子生物学机制，阐明NOT2s在植物抗病反应中的功能，进而丰富JA介导的抗病信号网络。