TAXIS OF RHIZOBIA TO LOCALIZED SITES ON LEGUME ROOTS

根瘤菌向豆科根部局部部位的趋向

• 批准号: 3296626
• 负责人: KOSTIA BERGMAN
• 金额: $ 12.39万
• 依托单位: NORTHEASTERN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-02-01 至 1992-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3296626
• 关键词: Escherichia coli; Leguminoseae; Rhizobiaceae; alfalfa; bacterial disease; bacterial genetics; chemotaxis; genetic transcription; high performance liquid chromatography; host organism interaction; mutant; nitrogen fixation; plant diseases; plant proteins; protein sequence; root; symbiosis

Many types of bacteria are equipped for chemotaxis, the movement toward or away from specific chemicals. Investigators of this behavior in enteric bacteria have often emphasized its importance as a model for the sensory physiology or even the central nervous system physiology of higher organisms. The long- term aims of this project are to extend the powerful methods developed in such work toward an understanding of the role that bacterial chemotaxis has in microbial ecology. Previous experiments demonstrate that the chemotaxis of rhizobia to localized sites on the surface of legume roots plays a role in the infection process. This infection initiates a symbiotic association for nitrogen fixation which clearly must be maximized if we are to continue to meet human nutritional needs in a time of decreasing availability of traditional energy sources. Attractant activity of purified chemicals and plant root extracts is assayed in a simple, sort agar plate assay. This assay is made specific by the use of two mutants of Rhizobium meliloti strain SU47 that no longer detect any pure substance tested (primarily sugar and amino acids) but still detect the localized site attractant. The structure of two peptides, isolated from alalfa root tips, that attract these two mutants and the wild type at low concentration will be determined following further improvements in the purification scheme. Mutants that have a specific defect in the response to these plant substances will be isolated and used for tests of the hypothesis that the response has a role in the infection process. A relable technique for permanant marking of small sites will allow further ultrastructural studies of the localized sites of bacterial accumulation. Particular emphasis will be placed on time course studies that can test the hypothesis that these are potential infection sites. The findings of these studies will be relevant for study of bacterial infection in other complex microenvironments including, for example, the mouth and the gut.

许多类型的细菌配备了趋化性， 朝着或远离特定化学物质运动。 调查人员 肠细菌的这种行为经常强调 作为感官生理或什至 高等生物的中枢神经系统生理。 长期 该项目的术语目标是扩展强大的方法 在这样的工作中发展，以理解 细菌趋化性在微生物生态学中具有。 以前的 实验表明根茎的趋化性 豆类根表面的局部位点在 感染过程。 这种感染引发了共生关联 对于氮固定，如果我们是，显然必须最大化 在一段时间内继续满足人类的营养需求 降低传统能源的可用性。 纯化化学品和植物根提取物的吸引力活性 用简单的，排序的琼脂板测定法进行测定。 该测定是制定的 特异性使用两个根瘤菌菌株的突变体 SU47不再检测到任何纯种物质（主要是 糖和氨基酸），但仍检测到局部位置 吸引剂。 从阿拉尔法分离的两个肽的结构 根尖，吸引这两个突变体和低点的野生型 在进一步改进之后，将确定集中度 在纯化方案中。 具有特定缺陷的突变体 对这些植物物质的反应将被隔离并使用 为了检验该假设，即响应在 感染过程。 用于永久标记小地点的可靠技术将 允许对局部部位的进一步超微结构研究 细菌积累。 特别重点会放在 时间课程研究可以检验这些假设是 潜在的感染部位。 这些研究的发现将与研究有关 其他复杂的微环境中的细菌感染，包括 例如，嘴和肠道。