我国干旱区湖滨盐碱化湿地土壤的生态修复机理研究

Soil salinization is one of the major problems of the lake wetland ecosystem degradation in arid region of China. The phytoremediation of salinized soil is considered as the most cost-effective measure using halophytes. Preliminary study shows that arbuscular mycorrhizal (AM) fungi can improve the salt tolerance of halophytes. However, few studies have focused on the mechanisms and effects of AM fungi-halophytes combination on the ecological remediation of salinized wetland soils. Based on the screening effective AM fungi species and halophytes applied to the ecological remediation of salinized wetland soils, the pot experiments are designed to study the mechanisms and effects of AM fungi and halophytes symbiosis on improving the soil properties of salinized wetlands and increasing salt uptake of halophytes. Moreover, modern environmental and biological analytical techniques will be used to systematically study the physiological, biochemical, and molecular mechanisms involved in AM fungi and halophyte on the ecological remediation of salinized wetland soils. The mechanisms will be investigated with respect to improve photosynthesis, water use efficiency, antioxidant enzyme activity, osmotic balance and the micro-distribution of Na+ in mycorrizal root and extraradical hyphae, and regulate the plasma memebrane and tonoplast Na+/H+ antiporter gene and aquaporin genes expression. Na+/H+ antiporter gene code the vacuolar proteins in Na+ compartmentalizaiton and the plasma membrane proteins in Na+ transport out of the cell. Aquaporin is a family of transmembrane protein that facilitates the transport of water across the cell membrane. The research will explore the feasibility of using AM fungi-halophytes combination for the ecological remediation of salinized wetland soils in the lakeside. More importantly, the research will provide theoretical basis and technical support for the ecological restoration of salinized lake wetland ecosystem in arid region of China.

盐碱化是我国干旱区湖泊湿地生态系统退化面临的主要问题，利用盐生植物修复盐碱化土壤是最为经济有效的措施。初步研究显示AM真菌可提高盐生植物的耐盐碱性，但AM真菌和盐生植物联合对盐碱化湿地土壤的生态修复机理研究尚属空白。本项目在筛选提高盐碱化湿地土壤生态修复效率的AM真菌和盐生植物的基础上，研究AM真菌-盐生植物共生对改善盐碱化湿地土壤环境和促进盐分吸收的作用；利用现代环境分析技术和生物学技术，从改善光合作用、水分利用效率、抗氧化酶活性、渗透平衡和菌根、根外菌丝中Na+微区分布等生理生化机制，调控质膜、液泡膜负责Na+区隔化或外排的Na+/H+逆向转运蛋白基因和高效跨膜转运水分子的水孔蛋白基因表达等分子机制系统研究AM真菌-盐生植物联合对盐碱化湿地土壤的生态修复机理。探索AM真菌-盐生植物联合用于湖滨盐碱化湿地土壤生态修复的可行性，为恢复我国干旱区盐碱化湖泊湿地生态系统提供科学依据和技术支持。

盐碱化是我国干旱区湖泊湿地生态系统退化面临的主要问题，利用盐生植物修复盐碱化土壤是最为经济有效的措施。初步研究显示AM真菌可提高盐生植物耐盐碱性，但AM真菌和盐生植物联合对盐碱化湿地土壤的生态修复机理研究尚属空白。本项目筛选获得盐地碱蓬和AM真菌F.mosseae的组合可显著提高盐碱化湿地土壤的生态修复效率；AM真菌可显著促进盐生植物对盐分离子的吸收累积，增加叶片渗透调节物质脯氨酸、可溶性蛋白和可溶性糖含量，降低叶片MDA含量。在0 mM和200 mM盐浓度下，AM真菌没有显著影响盐地碱蓬地上部SsNHX1、SsSOS1、SsVHA-B和SsPIP的表达量；在100 mM盐浓度下，AM真菌上调了地上部SsSOS1表达量，下调了根部SsSOS1和SsNHX1表达量；在400 mM盐浓度下，AM真菌增加了盐地碱蓬地上部K浓度和K:Na比，降低了地上部SsNHX1和根部SsSOS1的表达量，对于Na+/H+逆向转运蛋白的调控有利于驱动Na滞留在根部，从而减少Na转运和区隔到叶片中；研究结果表明，AM真菌对盐生植物耐盐相关基因产生的差异性调控可能与环境中Na+浓度相关联。在盐胁迫下，AM真菌显著改变了盐地碱蓬根际细菌群落的组成和结构，促进了与植物生长和营养元素循环相关的细菌显著富集，提高了盐地碱蓬的适应性。转录组学和蛋白质组学分析显示，AM真菌诱导的差异表达基因和差异丰度蛋白主要富集在碳水化合物代谢和能量代谢通路；进一步的富集分析显示，光合器官中的碳固定、光合作用通路、叶绿素和卟啉合成通路等与光合作用相关通路都被显著影响，揭示了AM真菌可能调控了盐地碱蓬的光合作用，影响了植物的碳积累；但是，AM真菌未显著影响与抗氧化防御系统相关的基因和蛋白，且下调了维生素B6代谢通路的基因，表明AM真菌可能未通过调控盐生植物的抗氧化系统增加其对盐胁迫的耐受性，与对甜土植物的调控存在差异。本项目的研究结果，为探索AM真菌-盐生植物联合用于湖滨盐碱化湿地土壤生态修复的可行性，为恢复我国干旱区盐碱化湖泊湿地生态系统提供科学依据和技术支持。