Dissertation Research: Coevolution in the Legume-Rhizobiaceae Symbiosis: A Phylogenetic Test of Codivergence

论文研究：豆科植物-根瘤菌科共生的共同进化：共分化的系统发育测试

• 批准号: 9623537
• 负责人: Margaret Riley
• 金额: $ 0.92万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-05-15 至 1998-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9623537&HistoricalAwards=false
• 关键词: Dissertation; Research; Coevolution; Legume; Rhizobiaceae

9623537 Riley Members of a bacterial family Rhizobiaceae are known for their nitrogen-fixing, symbiotic relationship with a variety of legume host plants. The soil bacteria forms nodules on legume roots, where it fixes atmospheric nitrogen into a form which the plant can use. The goal of this study is to test for coevolution between these two symbiotic partners. Similarity of branching patterns in phylogenies (or, phylogenetic congruence) is strong evidence of a shared evolutionary history between symbionts, and will be used to test for coevolution between the Rhizobeaceae and their legume hosts. Research will determine whether genetic information enabling the bacteria to become a symbiont of the plant, the sym region, has coevolved with genes of the host plant during the process of host plant diversification. Findings will also illustrate the contribution of geographic separation among spatially isolated strains to genetic divergence in rhizobia and show whether nodulation genes have been transferred between different rhizobial chromosomal lineages over the evolutionary history of rhizobia. Understanding the evolution of associations between Rhizobiaceae and legumes is important agriculturally. Legumes include the important crop plants, soybeans, peas, and chickpeas. The nitrogen-fixing symbiosis with rhizobia has also been exploited as a way to replenish soil with fixed nitrogen without using chemical fertilizers. Understanding how rhizobia/host relationships arose, the stability of the association throughout the diversification of legumes, and the types of evolutionary pressures which maintain the symbiosis in nature is critical if crop production and soil fertility are to be improved by manipulating the symbiosis.

小行星9623537 根瘤菌科细菌的成员以其固氮、与多种豆科宿主植物的共生关系而闻名。 土壤细菌在豆科植物的根部形成根瘤，在那里它将大气中的氮固定成植物可以利用的形式。 这项研究的目的是测试这两个共生伙伴之间的共同进化。 相似的分支模式在共生体（或系统发育一致性）是一个共享的进化历史之间的共生体的有力证据，并将被用来测试之间的共生植物和他们的豆科宿主的共同进化。研究将确定使细菌成为植物共生体的遗传信息，即sym区域，是否在宿主植物多样化的过程中与宿主植物的基因共同进化。 研究结果还将说明空间隔离菌株之间的地理分离的贡献，在根瘤菌的遗传分化，并显示是否已在根瘤菌的进化历史不同的根瘤菌染色体谱系之间转移的根瘤菌的基因。 了解根瘤菌科和豆科植物之间的关系在农业上具有重要意义。 豆类包括重要的作物植物，大豆，豌豆和鹰嘴豆。 与根瘤菌的固氮共生也被用作一种在不使用化学肥料的情况下用固定氮补充土壤的方法。 了解根瘤菌/宿主关系是如何产生的，在豆科植物的多样化过程中该协会的稳定性，以及维持自然界共生关系的进化压力的类型，如果要通过操纵共生关系来提高作物产量和土壤肥力，则至关重要。