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: 1257938
• 负责人: Katy Heath
• 金额: $ 14.5万
• 依托单位: University of Illinois at Urbana-Champaign
• 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 2017-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1257938&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.

人为引起的全球变化的一个鲜为人知的方面是，通过制造肥料和化石燃料的燃烧，氮对植物的可用性增加了一倍。氮是最强烈限制植物在陆地上生长的元素，因此一种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自然氮来源，豌豆家族中植物物种之间的关联，称为豆类；和根栖息的细菌，称为根瘤菌，它们将空气中的氮气转化为铵，铵是植物用来使蛋白质和其他分子生命所必需的氮的形式。 可以直接从土壤中获得更多氮的豆类往往会少于根瘤菌，这些根瘤菌需要植物的碳水化合物。 随着时间的流逝，预计氮的全球变化将减少根瘤菌的丰度，并驱动较少合作的根瘤菌的演变，从而使植物可用的氮较少。 反过来，这可能会增加对合成肥料的依赖，并反馈全球氮循环。 该项目将在Kellogg生物站的长期生态研究（LTER）地点的氮添加实验中使用现有的22年历史实验，作为在未来几十年中可能发生的天然氮供应可能发生的窗口。该项目的更广泛影响包括在科学劳动力中申请农业，学生研究培训以及促进多样性的促进。许多种植系统，包括大豆和玉米的旋转，都将豆类和根瘤菌之间的关联作为氮的来源。 基于询问的两个大型本科课程的基于询问的实验室将基于该项目，并通过教授生态学的问题和实验来出版，这是科学教育者广泛使用的资源。为了促进学术界的公平性和多样性，该项目将创建基于网络的材料并组织小组讨论，以指导来自不同背景的本科生，通过申请并在研究生院申请并取得成功。