Molecular Control of Ammonia Assimilation in Alfalfa Root Nodules

苜蓿根瘤氨同化的分子控制

• 批准号: 9206890
• 负责人: Carroll Vance
• 金额: $ 27.5万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-01 至 1996-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9206890&HistoricalAwards=false
• 关键词: Molecular; Control; Ammonia; Assimilation; Alfalfa

The research in this proposal will focus on host plant biochemical and molecular mechanisms that regulate phosphoenolpyruvate carboxylase and NADH-glutamate synthase, key enzymes involved in assimilation of symbiotically fixed nitrogen in alfalfa (Medicago sativa L.) root nodules. This proposal is based on two hypotheses. The first is that expression of the nodule PEPC and NADH-GOGAT genes is regulated by cis-acting element(s) that interact with one or more trans-acting factors and the activity of these factors is a function of one or more of the following: nodule organogenesis, effective bacteroids, ammonium ion availability and/or oxygen concentration. The second is that direct genetic alteration of nodule PEPC and/or NADH-GOGAT enzyme activities impacts upon nodule nitrogen fixation and ammonia assimilation. The specific objectives include: 1) isolation and sequence analysis of PEPC and NADH- GOGAT genomic clones and initial characterization of the promoter regions of these gene by deletion analysis and by protein-DNA binding studies: 2) localization in planta of PEPC and NADH- GOGAT proteins and mRNAs by immunogold staining and by in situ hybridization; and 3) alteration in planta of PEPC and NADH- GOGAT activities through direct modification of enzyme synthesis by the expression of transformed genes. Knowledge gained from these studies will enhance our fundamental understanding of plant genes involved in ammonia assimilation and may facilitate crop improvement through the development of strategies to modify nitrogen metabolism.

该提案中的研究将集中于宿主植物生化和分子机制，这些机制调节磷酸烯醇丙酮酸羧化酶和NADH-谷氨酸合酶，这是参与alfalfa（Medicago sativa L.）根nodules中共生固定氮的关键酶。 该提议基于两个假设。 首先是，结节PEPC和NADH-GOGAT基因的表达受顺式作用元件的调节，这些元件与一个或多个反式作用因子相互作用，而这些因素的活性是一个或多个以下一个或多个结节器官发生的函数：有效的细菌，有效的细菌，氨离子可用性和/或氧浓度。 第二个是结节PEPC和/或NADH-GOGAT酶活性的直接遗传改变对结节氮的固定和氨气同化会影响。 具体目标包括：1）PEPC和NADH-GOGAT基因组克隆的隔离和序列分析，以及通过缺失分析和蛋白-DNA结合研究对这些基因的启动子区域的初步表征：2）通过Immunogold stemations in Immunogold astu hybrization in Immunogold steusiation in Immunogold satu hybrization in sera hybrization serbriative serbriative serbriative serbriative serbriative; 3）通过通过转化基因的表达直接修饰酶合成的PEPC和NADH-GOGAT活性的改变。 从这些研究中获得的知识将增强我们对参与氨水含量的植物基因的基本理解，并通过制定改变氮代谢的策略来促进作物改善。