谷氨酸和γ-氨基丁酸在浮萍快速应答镉胁迫中的作用研究

镉污染对植物光合作用、元素吸收和生长发育造成严重危害。浮萍可以有效修复镉污染水体和稻田水，解析浮萍快速响应镉信号机制对于环境治理具有重要意义。本项目组前期发现，镉胁迫可引起浮萍组织中谷氨酸和γ-氨基丁酸含量发生明显的变化，并促发谷氨酸受体蛋白表达上调和钙信号的快速响应；外源谷氨酸处理能引起浮萍根部钙离子外排，并增强浮萍对镉抗性，而γ-氨基丁酸则导致钙离子内流、镉抗性减弱。这提示“谷氨酸和γ-氨基丁酸浓度稳态”在浮萍应答镉胁迫中发挥了重要作用。本项目拟采用基因芯片、基因编辑、和非损伤微测等方法，观察谷氨酸和γ-氨基丁酸及其代谢酶在浮萍应答镉胁迫中的变化规律和对浮萍抗性的影响，研究其受体蛋白和钙信号在谷氨酸和γ-氨基丁酸应答镉胁迫中的作用，阐明谷氨酸和γ-氨基丁酸稳态在浮萍快速响应镉胁迫中起作用的分子机制。研究结果将丰富植物对重金属胁迫的抗性理论内容，为利用浮萍修复水域环境重金属污染奠定基础。

Cadmium (Cd) pollution is harmful to plant photosynthesis, element absorption and growth. Duckweed could be applied in phytoremediation by effectively removing Cd from polluted water and paddy water. Therefore, it is significant to study the rapid signal response to Cd in duckweed for environmental phytoremediation. According to our previous studies, Cd stress resulted a significant change in Glutamate (Glu) and γ-aminobutyric acid (GABA) content in duckweed tissues, which correlated with the upregulation of Glutamate Receptor-Like Proteins and the calcium (Ca) signal responds. Besides, exogenous Glu triggered the Ca signal via modifying the instantaneous Ca2+ flux from influx to efflux in the rhizoid of duckweed, and Cd tolerance was enhanced concurrently. However, exogenous GABA treatment resulted in a Ca2+ efflux in the rhizoid, and accompanied with a weak resistance to Cd in duckweed. This indicates that Glu/GABA ratio is important for responding to Cd. In this project, we propose to study the response variation rules and the function of Glu, GABA and their metabolic enzymes during the response to cadmium stress using techniques such as gene sequencing, gene editing and noninvasive micro-test technique. Moreover, the role of receptor protein and calcium signal in glutamate and GABA response to cadmium stress will be studied. This project is expected to clarify the role of the Glu and GABA concentration homeostasis during the rapid respond to Cd in duckweed. Moreover, the project will enriches the theory of plant resistance to Cd, and provide the new materials and new method for the phytoremediation by duckweed.