大豆根瘤中硫氮互作调控网络组件及机理研究

Although the soybean root nodule symbiosis（RNS）leads to the most economical nitrogen fertilizer by fixing atmospheric nitrogen, the mechanisms involved in the interaction between the rhizospheric sulfur and the nodule nitrogen are just beginning to be understood. The previous study by the proposer had shown that the interaction between sulfur and nitrogen influenced the soybean seed’s amino acid composition, protein subunits composition and the expression of key enzyme genes during the sulfur assimilation pathway. But the regulatory signal and the functional components involved in the sulfur-nodule nitrogen interaction still need to be further explored. This project aims to the study of systemic regulate signal of sulfur and nitrogen metabolism, and focus on the interactions mechanism between exogenous sulfur and nodules nitrogen. Two different types of nitrogen efficiency soybeans which screened before will be used as plant materials. The split-root system approach, qRT–PCR and metabonomics detection methods will be used for mineral nutrition research. The impacts of sufficient sulfur or sulfur starvation on nitrogen fixation capacity of soybean nodules can be studied. The metabolites and the expressing of related genes which connect the nitrogen assimilation and sulfur assimilation will be analyzed, so as to reveal the space-time characteristics, components and its mechanism of regulatory network of sulfur-nitrogen interactions in root and nodules of soybean. Overall, the present project aims to improve the soybean nodules’ ability to nitrogen fixation, which will alleviate the environment and energy problem.

大豆根瘤共生固氮系统(RNS)是自然界最经济的氮肥来源，但是关于根际硫素营养对根瘤固氮的调控机制还不十分明确。申请人前期研究发现硫氮互作影响大豆子粒氨基酸组分、蛋白亚基组成和硫素同化代谢关键酶基因的表达，但是硫素同根瘤氮互作的调控信号和功能因子仍需要进一步探究。本项目从硫氮代谢调控信号的系统变化规律出发，研究根瘤固氮与外源硫素之间的互作机制。以前期筛选的不同氮效率类型的大豆作为试验材料，利用分根法、qRT-PCR、代谢组学检测等方法，分析硫素丰缺对大豆根瘤固氮能力的影响规律，明确连接硫氮代谢的纽带性质代谢物和相关基因的响应规律，从而揭示根和根瘤中硫氮互作的时空特性、调控网络组件及机理。对于提高大豆根瘤固氮能力，缓解氮肥带来的环境、能源问题具有重要的意义。

大豆根瘤共生固氮系统(RNS)是自然界最经济的氮肥来源，但是关于根际硫素营养对根瘤固氮的调控机制还不十分明确。本项目通过筛选不同氮效率类型的大豆，分析硫素丰缺对不同氮效率类型大豆根瘤固氮能力的影响规律。研究结果表明，不同氮效率类型大豆的结瘤特性有显著差异，大豆的根瘤特性及生长发育受硫素丰缺影响较小，推断硫素胁迫对大豆结瘤特性的调控是在整株水平上的。不同硫氮营养条件对大豆子粒硫素、氮素、N/S、含硫氨基酸组分有较大影响，高氮条件下施硫处理明显提高子粒含硫氨基酸总量。