Ca2+/CaM及钙离子通道对盐胁迫下发芽大豆累积GABA的介导作用

Salt stress is confirmed as an effective way to accumulate GABA in germinated soybeans. However, soybean plants are relatively salt-sensitive and its growth, development and biomass are significantly suppressed by salt stress. Exogenous calcium counters the harmful effect of salt stress and increases the biomass and GABA content of germinating soybeans. Nevertheless, the precise molecular mechanism is still clear. In the present study, we will investigate the regulating effect of exogenous and endogenous Ca2+, calcium ion channel and calmodulin on physiological indexes, antioxidase system, endogenous hormone, GABA synthesis related enzymes activity and its gene expression and proteome expression patterns through the use of calcium ion and its chelating agent, calmodulin and its inhibitor and calcium ion channel inhibitor. Meanwhile, aminoguanidine, inhibitor of amine oxidase, is used to study the contribution ratio of GABA shunt and polyamine degradation pathway for GABA accumulation. The Ca2+/CaM and calcium ion channel regulatory networks of GABA accumulation in germinating soybeans response to salt stress will be built under levels of physiology and biochemistry, gene expression and proteome. The study result will be helpful to enrich the theory of plant seeds accumulation GABA during germinating under the artificial condition. It will also have real-life relevance of drive the development of the riched-GABA sprouts industry.

大豆籽粒于盐胁迫下发芽是有效累积γ-氨基丁酸（GABA）的方式，然而大豆作为盐敏感型作物，经盐胁迫处理其生长和生物量受到严重抑制。项目组前期研究发现CaCl2可解除盐胁迫对发芽大豆的生长抑制，并促进GABA累积，但是其作用机制仍有待阐明。在此基础上，本项目利用Ca2+及其螯合剂、钙调素（CaM）及其抑制剂和钙离子通道抑制剂处理以研究外源和内源Ca2+、钙离子通道和钙调素对盐胁迫下发芽大豆生理指标、抗氧化酶系统、内源激素、GABA代谢关键酶活力及其基因表达和蛋白表达谱的调控作用，并利用氨基胍抑制多胺降解途径，解析其平衡多胺降解途径和GABA支路合成GABA的机制，结合生理生化、基因转录和蛋白质组三个层面系统构建发芽大豆应答盐胁迫累积GABA的Ca2+/CaM及钙离子通道调控网络。研究结果有助于丰富植物籽粒发芽累积GABA理论，对推动我国富含GABA的功能性芽菜类食品产业化发展具有实际意义。

大豆籽粒于盐胁迫下发芽是富集γ-氨基丁酸（GABA）的有效方式，然而大豆作为盐敏感型作物，经盐胁迫处理其生长和生物量受到严重抑制。项目组在CaCl2可解除盐胁迫对发芽大豆的生长抑制并促进GABA富集这一研究现象的基础上，运用外加法和内源抑制法，利用荧光定量PCR和i-TRAQ蛋白组学技术，从生理生化、基因转录和蛋白表达三个层面阐述其作用机制。.本项目研究工作明确了盐胁迫下Ca2+/CaM及钙离子通道对发芽大豆生理代谢的调控作用，证实CaCl2是通过提高抗氧化酶活力来缓解NaCl胁迫下发芽大豆的抑制效应，抑制内源钙库的释放对NaCl胁迫下GABA富集的影响小于抑制质膜钙离子通道；明晰了Ca2+处理下发芽大豆中GABA两条代谢途径的贡献率，NaCl胁迫下经Ca2+处理可促进发芽大豆中GABA富集，但CaCl2和EGTA处理下多胺降解途径对GABA富集贡献降低；同时，研究阐明了NaCl 胁迫下Ca2+调控发芽大豆中GABA代谢关键酶的基因表达和蛋白谱变化，发现NaCl 联合 CaCl2 处理通过促进基因表达量增加及提高相关代谢酶活力以富集 GABA，同时促进核糖体及次生代谢物生物合成途径中蛋白表达从而有利于发芽大豆体内GABA的富集。本项目的实施为促进商品化生产豆类健康食品提供科学依据和技术支撑，推动我国经济和社会发展。.