铵是植物生长必需的养分离子，但其过量时易造成毒害。在铵胁迫下维持植物体内有效的铵钾平衡是提高植物忍耐铵毒害的关键。但目前对铵钾平衡调控过程的分子生物学机制研究尚未完全展开。本研究以本实验室先前筛选验证的铵胁迫下铵钾调控失衡的拟南芥突变体amos2为核心材料，应用现代植物生物学和营养学等先进技术，克隆铵钾平衡调控基因AMOS2，并以此为突破口研究AMOS2基因功能及其调控铵钾平衡的分子生理途径。通过分析AMOS2表达定位受不同铵钾条件调控的特征及其启动子区应答铵钾信号的关键元件，并拟结合电生理、基因芯片技术，初步研究AMOS2基因的特征与功能；分析铵胁迫下WT和amos2体内铵钾吸收、转运及胞质内平衡的差异，选定AMOS2的作用途径。研究结果将有助于更深入地研究高铵下拟南芥通过调控内部铵钾平衡来提高铵抗性的生物学途径及机理，丰富对植物感知适应高铵环境的认识，为提高铵态氮利用率提供新的理论知识

Ammonium (NH4+) is necessary for normal life in most organisms, but is toxic to the cells when excess. NH4+/K+ homeostasis is thought to be key to protect the plants from ammonium stress, but molecular mechanisms behind the interaction of K+ and NH4+ toxicity is not known. In this study, we use Arabidopsis ammonium overly sensitive 2 (amos2) mutant identified previously in our lab, which defecting NH4+/K+ homeostasis compared with wild type in response to NH4+ stress, to clone the AMOS2 gene and explore the gene function and the AMOS1-mediated NH4+/K+ homeostasis molecular pathway by combination of modern plant molecular biological and plant nutrition approaches. Firstly, to research the characteristic and function of AMOS2 by analyzing the expression orientation and important promoter binding elements for response to the vary NH4+/K+ radio, combination of electrophysiological techniques and gene chip technology. Secondly, to confirm the molecular pathway by analyzing the difference between WT and mutant in NH4+/K+ uptake, transport and cytosolic homeostasis. Collectively, this program is designed to reveal AMOS2 gene function in control NH4+/K+ homeostasis and the role of AMOS2 in protecting plant development from ammonium stress. It is very helpful for the improvement of ammonium use efficiency in higher plants under high ammonium stress.