硅促进盐胁迫下番茄根系水分吸收的信号调控研究

Silicon can increase plant tolerance to salt stress. However, the mechanisms are still not clear. Previous studies by us and other researchers have indicated that silicon can increase salt tolerance of plants through enhancing root water uptake, and it also regulates the levels of ABA and ethylene under salt stress. However, the signaling regulation mechanism for silicon-mediated enhancement of root water uptake still remains unclear. ABA and ethylene play important regulatory roles in root water uptake, and we found that they were involved in responses in silicon-mediated salt tolerance. Based on these, the following research will be conducted in this project using tomato as the experimental material: (1) analyzing the regulatory roles of silicon on ABA and ethylene metabolisms under salt stress, and determining the silicon-regulated key genes involved in the metabolisms; (2) clarifying the roles of ABA and ethylene in silicon-mediated enhancement of root water uptake and their possible upstream and downstream relationship under salt stress by using ABA- and ethylene-deficient mutants, their biosynthesis and signaling inhibitors, and exogenous application of these plant hormones; (3) verifying the roles of ABA and ethylene in silicon-mediated enhancement of root water uptake and their upstream/downstream relationship under salt stress by using RNAi or overexpression transgenic plants of the key genes involved in the upstream signal (ABA or ethylene) metabolism. This research will help elucidate the signaling regulation mechanism for silicon-mediated enhancement of root water uptake in tomato under salt stress, and provide a theoretical basis for silicon application in production.

硅可提高植物的耐盐性，但其作用机理仍不清楚。前人和申请人研究表明，硅可通过促进盐胁迫下根系的水分吸收而提高植物的耐盐性、并调控了ABA和乙烯水平，但对硅促进水分吸收的信号调控机制尚不清楚。ABA和乙烯在根系水分吸收中起着重要的调控作用，我们发现二者参与了硅的耐盐反应。基于此，本项目拟以番茄为试材，解析硅对盐胁迫下ABA和乙烯代谢的调控作用、确定硅调控的关键代谢酶基因；利用ABA和乙烯缺失突变体及其合成/信号途径抑制剂、并结合施用这些激素，阐明ABA和乙烯在硅促进盐胁迫下根系水分吸收中的作用，并初步确定其可能的上下游关系；克隆ABA和乙烯两者中处于信号上游激素的关键代谢酶基因，构建其RNAi/过表达转化体系并获得转基因材料，验证ABA和乙烯在硅促进盐胁迫下根系水分吸收中的作用及其上下游信号关系。本研究将阐明硅促进盐胁迫下番茄根系水分吸收的信号调控机制，为硅肥在生产中的应用提供理论依据。

硅提高植物耐盐性的机理仍不太清楚。项目组以番茄为材料，并辅以黄瓜的应用，研究了硅对植物的耐盐性、水分吸收、ABA和乙烯代谢的影响，分析了ABA和乙烯合成抑制剂对番茄水分吸收的影响，利用ABA和乙烯合成番茄突变体并结合抑制剂的使用分析了ABA和乙烯在硅诱导植物耐盐性中的作用，并分析了与乙烯代谢紧密相关的多胺水平及其代谢的影响，在番茄中过表达SAMDC并验证了转基因株系的耐盐性和水分吸收。结果显示，硅处理改善了盐胁迫下番茄的生长，提高了番茄的水分吸收和PIP基因的表达。在盐胁迫下，硅处理抑制了番茄ABA的过量积累，降低了ACC合成酶基因的表达和乙烯水平。抑制剂试验表明，ABA和乙烯均参与了硅促进盐胁迫下番茄的水分吸收过程和耐盐性的提高。在乙烯突变体中，Si的耐盐效果不明显；而在ABA合成突变体中，加入乙烯合成抑制剂则抑制了Si的耐盐效果，表明乙烯信号可能在硅诱导番茄抗盐性信号通路的上游。硅促进了盐胁迫下番茄和黄瓜中多胺的合成。过表达SAMDC改善了盐胁迫下番茄幼苗的生长和水分吸收，提高了耐盐性。结果表明，乙烯及与其紧密关联的多胺可能在硅促进盐胁迫下番茄水分吸收中发挥重要的作用。本项目研究为进一步弄清硅提高植物耐盐性的分子机理奠定了基础。