The Ecological Significance of Molecular Signaling Between Bacterial Populations on Plant Roots: Effect on Competitionand Coexistence

植物根系细菌群体间分子信号传导的生态意义：对竞争与共存的影响

• 批准号: 9514074
• 负责人: Leland Pierson III
• 金额: $ 20.8万
• 依托单位: University of Arizona
• 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: 1996-02-01 至 1999-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9514074&HistoricalAwards=false
• 关键词: Ecological; Significance; Molecular; Signaling; Between

9514074 Pierson The rhizosphere, the zone of soil surrounding plant roots, contains greater amounts of nutrients in the form of root exudate than the surrounding soil. Therefore, microbial competition for these root exudates is intense. In response to this competition, bacteria have evolved diverse competitive mechanisms to allow them to compete for these nutrients. One benefit of the expression of these competitive mechanisms is the inhibition of plant pathogens, commonly termed biological control. However, commercial use of biological control as been limited by inconsistent performance. This is the result of our lack of understanding of the factors, including the plant host and the natural microbial community, that affect the expression of these competitive genes in the rhizosphere. Pseudomonas aureofaciens 30-84, one of the best genetically defined biological control organisms, produces phenazine antibiotics. Phenazine production is the primary mechanism responsible for the competitive fitness of this species in the rhizosphere and for its ability to suppress plant pathogens. We have shown that this bacterium regulates the expression of the genes encoding phenazine production through the recognition of a diffusible signal encoded by the gene phzI. Recently, it has been shown that populations of diverse bacteria rely on the accumulation of structurally similar signals to trigger the expression of host-associated genes. We have shown that the expression of genes involved in phenazine production in strain 30-84 is influenced by the production of diffusible signals produced by other rhizosphere bacteria. The ecological significance of these interactions is that competing strains may be able to influence the outcome of competition by affecting the regulation of a competitive mechanism at a genetic level. The proposed research will directly test the effect of diffusible signals produced by other populations of bacteria on phenazine gene expression in P. aureofaciens, including the effect of interactions on population densities in situ on plant roots.

小行星9514074 根际，植物根系周围的土壤区域，比周围的土壤含有更多的养分，以根系分泌物的形式存在。 因此，微生物对这些根分泌物的竞争是激烈的。 为了应对这种竞争，细菌进化出了多种竞争机制，使它们能够竞争这些营养素。 表达这些竞争机制的一个益处是抑制植物病原体，通常称为生物防治。 然而，生物防治的商业应用受到性能不一致的限制。 这是由于我们对影响这些竞争基因在根际表达的因素缺乏了解，包括植物宿主和自然微生物群落。 金色假单胞菌30-84是最好的遗传定义的生物控制生物体之一，产生吩嗪抗生素。吩嗪的生产是主要的机制，负责竞争适合这个物种在根际和其能力，以抑制植物病原体。我们已经表明，这种细菌通过识别由基因phzI编码的可扩散信号来调节编码吩嗪生产的基因的表达。 最近，研究表明，不同细菌群体依赖于结构相似信号的积累来触发宿主相关基因的表达。 我们已经表明，在菌株30-84中参与吩嗪生产的基因的表达受到其他根际细菌产生的可扩散信号的影响。 这些相互作用的生态意义在于，竞争菌株可能能够通过影响遗传水平上竞争机制的调节来影响竞争的结果。 拟议的研究将直接测试其他细菌种群产生的可扩散信号对P. aureofaciens中吩嗪基因表达的影响，包括相互作用对植物根部原位种群密度的影响。