Collaborative Research: Evolution in LTER Experiments: Ecological and Evolutionary Consequences of Long-Term Nitrogen Addition for the Legume-Rhizobium Mutualism

合作研究：LTER实验中的进化：长期添加氮对豆科植物-根瘤菌互利共生的生态和进化后果

• 批准号: 1257756
• 负责人: Jennifer Lau
• 金额: $ 35.5万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-03-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1257756&HistoricalAwards=false
• 关键词: Collaborative; Research; Evolution; LTER; Experiments

One little-publicized aspect of human-caused, global change has been a doubling of the availability of nitrogen to plants via the manufacture of fertilizer and the burning of fossil fuels. Nitrogen is the element that most strongly limits plant growth on land, so one ecological consequence is likely to be a rise in the total productivity of plants. A more surprising and opposite consequence could be a fall in a major, natural source of nitrogen for plants, the association between species of plants in the Pea Family, known as legumes; and root-dwelling bacteria, known as rhizobia, which convert nitrogen gas in the air into ammonium, a form of nitrogen that plants use to make proteins and other molecules essential for life. Legumes that can get more nitrogen directly from the soil tend less to associate with rhizobia, which demand carbohydrates from the plants. Over time, global change in nitrogen is thus predicted to reduce the abundance of rhizobia and drive the evolution of less cooperative rhizobia that make less nitrogen available to the plants. This could in turn increase reliance on synthetic fertilizers, and feedback upon the global nitrogen cycle. This project will use an existing, 22-year-old experiment in nitrogen addition experiment at the Long-Term Ecological Research (LTER) site at the Kellogg Biological Station as a window onto what may happen to the natural nitrogen supply over the decades to come. The broader impacts of this project include applications to agriculture, research training for students, and promotion of diversity in the scientific workforce. A number of cropping systems, including the rotation of soybeans and corn, use the association between legumes and rhizobia as a source of nitrogen. Inquiry-based labs for two large undergraduate courses will be based on the project and submitted for publication by Teaching Issues and Experiments in Ecology, a widely used resource for science educators. To promote equitability and diversity in the academic community, the project will create web-based materials and organize panel discussions that will guide undergraduate students from diverse backgrounds through the process of applying to and succeeding in graduate school.

人为造成的全球变化的一个鲜为人知的方面是，通过化肥的制造和化石燃料的燃烧，植物的氮供应量增加了一倍。氮是最强烈限制陆地植物生长的元素，因此一个生态后果可能是植物总生产力的提高。 更令人惊讶和相反的后果可能是植物的主要天然氮源的减少，即豌豆科植物物种之间的联系，即豆科植物；根部细菌（称为根瘤菌）可将空气中的氮气转化为铵，铵是植物用来制造蛋白质和其他生命必需分子的氮形式。 能够直接从土壤中获取更多氮的豆类植物与根瘤菌的联系较少，而根瘤菌需要从植物中获取碳水化合物。 因此，随着时间的推移，全球氮的变化预计将减少根瘤菌的丰度，并推动合作性较差的根瘤菌的进化，从而使植物可用的氮减少。 这反过来可能会增加对合成肥料的依赖，以及对全球氮循环的反馈。 该项目将利用凯洛格生物站长期生态研究 (LTER) 站点已有 22 年历史的氮添加实验作为了解未来几十年天然氮供应可能发生变化的窗口。该项目的更广泛影响包括农业应用、学生研究培训以及促进科学劳动力的多样性。许多种植系统，包括大豆和玉米的轮作，利用豆类和根瘤菌之间的联系作为氮源。 两门大型本科课程的探究式实验室将基于该项目，并提交给生态学教学问题和实验出版，这是科学教育工作者广泛使用的资源。为了促进学术界的公平和多样性，该项目将创建网络材料并组织小组讨论，指导来自不同背景的本科生申请研究生并取得成功。