RUI: Characterization of Glutathione S-transferase from Nitrogen-fixing Root Nodules

RUI：固氮根瘤中谷胱甘肽 S-转移酶的表征

• 批准号: 0517688
• 负责人: David Dalton
• 金额: --
• 依托单位: Reed College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0517688&HistoricalAwards=false
• 关键词: RUI; Characterization; Glutathione; transferase; Nitrogen

David DaltonProposal no. 0517688Characterization of Glutathione S-transferase from Nitrogen-fixing Root Nodules Legumes such as soybean, pea, alfalfa, and clover are valuable crops that are capable of fertilizing themselves through the process of nitrogen fixation. This process provides a source of nitrogen that is environmentally and economically advantageous since it minimizes pollution from the release of excess nitrogen (e.g. nitrates in runoff) and does not require the use of expensive chemical fertilizers. Nitrogen fixation in plants is an energy-intensive, aerobic process that requires substantial amounts of oxygen. This oxygen consumption leads to a fundamental dilemma since the environment within nodules promotes the formation of damaging, activated forms of oxygen such as hydrogen peroxide. Consequently, nodules contain high levels of antioxidants such as vitamin C (ascorbic acid) and numerous enzymes such as ascorbate peroxidase. Recent observations in this laboratory have revealed that soybean nodules also contain glutathione S-transferase (GST). This enzyme is best known for its role in detoxification of herbicides, but it is also capable of serving as an antioxidant. The objectives of this project are to define the role that GST plays in nitrogen-fixing legume nodules. Molecular techniques will be used to determine which forms of the GST gene family are expressed in nodules and what conditions stimulate the production of GST. Microscopic examination of nodule sections treated with fluorescent antibodies will be used to determine precisely where GTS is located. Nodulated plants will be exposed to various regimes involving chemical pro-oxidants to develop a model system to evaluate oxidative stress and to aid in identifying additional novel antioxidant proteins. The function of critical GST genes will be examined in transgenic plants in which the genes are down regulated. The discovery of GST in nodules is significant because it represents a potentially major overlooked aspect of oxygen relations in nodules. Since nitrogen fixation is likely limited by oxygen, any increase in the fundamental knowledge of antioxidants in nodules could have substantial impacts on future attempts to enhance performance of nitrogen-fixing crops. Furthermore, a confirmation of the antioxidant role of GST in nodules will lend credence to a similar role in other systems (including animals and microbes) where GST is present. This project fulfills NSF broader impact criteria by providing valuable preparation of undergraduate students, most of who are destined for graduate studies in plant biology. Students will be encouraged to attend meetings and to remain as a research technician and mentor for a few months following their graduation. Undergraduates engaged in senior thesis or summer projects will conduct the bulk of the research. Over the past 15 years, the P.I. has worked with 66 senior thesis research students and 47 summer research fellows; 35 of the thesis students were women. This grant will also provide summer research opportunities for high school students by establishing collaboration with the Apprenticeships in Science and Engineering (ASE) Program (http://www.saturdayacademy.pdx.edu/ase/). ASE helps students explore their interests and make informed educational and career decisions.

大卫道尔顿提案号0517688固氮根瘤中的谷氨酸S-转移酶的特性豆科植物如大豆、豌豆、苜蓿和三叶草是有价值的作物，它们能够通过固氮过程使自身生长。 该方法提供了一种在环境和经济上有利的氮源，因为它使来自过量氮（例如径流中的硝酸盐）释放的污染最小化，并且不需要使用昂贵的化学肥料。 植物固氮是一个需要大量氧气的能量密集型有氧过程。 这种氧的消耗导致了一个基本的困境，因为结核内的环境促进了有害的、活化形式的氧如过氧化氢的形成。 因此，根瘤含有高水平的抗氧化剂，如维生素C（抗坏血酸）和许多酶，如抗坏血酸过氧化物酶。 本实验室最近的观察表明，大豆根瘤也含有谷胱甘肽S-转移酶（GST）。这种酶以其在除草剂解毒中的作用而闻名，但它也能够作为抗氧化剂。 本项目的目标是确定GST在固氮豆科植物根瘤中的作用。 分子技术将用于确定哪些形式的GST基因家族在结节中表达，以及什么条件刺激GST的产生。 用荧光抗体处理的结节切片的显微镜检查将用于精确确定GTS的位置。 结瘤植物将暴露于各种制度，涉及化学促氧化剂，以开发一个模型系统，以评估氧化应激，并帮助确定其他新的抗氧化蛋白。 将在基因下调的转基因植物中检查关键GST基因的功能。 结核中GST的发现意义重大，因为它代表了结核中氧关系的一个潜在的主要被忽视的方面。 由于固氮作用很可能受到氧气的限制，因此对结核中抗氧化剂的基本知识的任何增加都可能对今后提高固氮作物性能的努力产生重大影响。 此外，GST在结节中的抗氧化作用的确认将使人们相信GST在存在的其他系统（包括动物和微生物）中具有类似的作用。 该项目通过为本科生提供有价值的准备，满足了NSF更广泛的影响标准，其中大多数人注定要在植物生物学研究生学习。 将鼓励学生参加会议，并继续作为研究技术人员和导师毕业后的几个月。 从事高级论文或暑期项目的本科生将进行大部分研究。 在过去的15年里，PI。与66名高年级论文研究生和47名暑期研究员合作;论文研究生中有35名妇女。 这项赠款还将通过与科学和工程学徒计划（ASE）（http：//www.saturdayacademy.pdx.edu/ase/）建立合作关系，为高中生提供夏季研究机会。 ASE帮助学生探索他们的兴趣，并做出明智的教育和职业决定。