蒺藜苜蓿NIN的SUMO化修饰在共生固氮中的功能研究

豆科植物-根瘤菌共生固氮是一种高效的生物固氮体系，也是植物获取氮源最为重要的方式之一。RWP-RK类转录因子NIN是调控根瘤菌侵染和根瘤器官发育过程的关键组分，但是NIN蛋白活性的调控及其在共生过程中的机制尚未见报道。我们前期研究发现，NIN具有保守的SUMO化修饰位点，且突变该位点不能完全互补其突变体的表型，表明SUMO化修饰对于NIN的功能至关重要。而且，SUMO化修饰的相关蛋白可以与NIN相互作用，并调控根瘤的形成。本项目拟在已有的研究基础上，利用蒺藜苜蓿为模式植物，通过对NIN的SUMO化动态修饰的研究，揭示蛋白翻译后修饰对NIN蛋白活性的调控及其在共生互作中的功能，为阐明共生固氮分子机制提供新的研究思路，完善共生固氮调控网络。

The legume-rhizobium symbiosis is an efficient biological nitrogen fixation system in nature，and one of the most important way for plant to obtain nitrogen. NIN, a RWP-RK type transcription factor, is essential for rhizobial infection and nodule organogenesis, but the regulation of its protein activity keeps unknown. We found that NIN has a conserved SUMO modification site, and mutated this site cannot fully rescue nin mutant phenotype. This result suggested that NIN SUMOylated modification is important for NIN’s function in nodulation. Moreover, the SUMO-associated proteins can interact with NIN and are required for nodulation. In this proposal, we will further study the NIN SUMOylated dynamic regulation and its function in symbiotic nitrogen fixation in Medicago truncatula. Our work will reveal the underlying mechanisms of NIN post-translation modification. It will provide new research ideas and improve the regulatory network in symbiotic interaction.