The evolution of parasitism in rhizobial bacteria

根瘤菌寄生的进化

• 批准号: 7111507
• 负责人: JOEL L SACHS
• 金额: $ 4.88万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7111507
• 关键词: Leguminoseae; Rhizobiaceae; evolution; microorganism classification; nucleic acid sequence; parasitism; postdoctoral investigator; symbiosis

DESCRIPTION (provided by applicant): Pathogen virulence is a main focus in evolutionary biology. Virulence theory investigates when harmful strains can spread, and is also useful to predict the evolution of beneficial symbionts. This theory predicts that beneficial bacteria which undergo infectious transmission can evolve to parasitize their hosts. Rhizobial symbionts of plants offer an intriguing case. Rhizobia are nitrogen-fixing bacteria critical to the growth of many legumes. These bacteria form symbiotic nodules on legume roots and fix nitrogen, a main resource for the plants. However, agricultural evidence suggests that rhizobia can parasitize legumes, by consuming plant carbon but then fixing no nitrogen. Here, we propose a combined field and lab approach to investigate rhizobial parasitism: I) We will ascertain the prevalence of rhizobial parasites and their effects on the fitness of wild legumes, II) We will study the evolution of rhizobial parasitism: phylogenetic analyses of sequenced isolates will reveal whether rhizobial parasitism arises sporadically or if parasites represent diverged clades and will distinguish among molecular models for the evolution of parasitism.

描述（由申请人提供）：病原体毒力是进化生物学的主要焦点。毒力理论研究有害菌株何时可以传播，也可用于预测有益共生体的进化。该理论预测，经历感染性传播的有益细菌可以进化以寄生于宿主。植物的根瘤菌共生体提供了一个有趣的例子。根瘤菌是固氮细菌，对许多豆科植物的生长至关重要。这些细菌在豆科植物根部形成共生根瘤并固定氮，这是植物的主要资源。然而，农业证据表明根瘤菌可以通过消耗植物碳但不固定氮来寄生豆科植物。在这里，我们提出了一种结合现场和实验室的方法来研究根瘤菌寄生：I）我们将确定根瘤菌寄生的流行及其对野生豆科植物适应性的影响，II）我们将研究根瘤菌寄生的进化：测序的系统发育分析分离株将揭示根瘤菌寄生是否偶尔出现，或者寄生虫是否代表不同的进化枝，并将区分根瘤菌进化的分子模型。寄生。