Physiological and molecular analysis of plant-microbe interactions in the rhizosphere

除了提供机械支持和从土壤中吸收水分和养分外，植物根还有助于感知和响应土壤环境。植物根通常通过分泌一种通常称为根分泌物的化合物混合物来对生物和/或非生物信号作出反应。与根际(紧邻根部周围的土层延伸到几毫米的土层)中与植物根相互作用的一组生物是细菌，这一组包括致病形式和有益形式。根分泌物中存在的化学成分影响细菌的生长和生理，这意味着根际细菌与植物根之间存在着动态的相互作用。根分泌物在致病和有益根-细菌相互作用中的化学成分和生物学功能，以及这种相互作用的遗传基础在很大程度上是未知的。拟议的研究计划将利用拟南芥现有的大量遗传资源来鉴定根分泌物中促进有益恶臭假单胞菌定殖的成分以及那些击退致病的丁香假单胞菌番茄DC3000的成分。此外，该计划将揭开根-微生物相互作用的遗传基础。在短期内，对根分泌物和相关基因表达的化学分析将导致代谢和分子标记的发展，这些标记可用于识别有选择地鼓励根际有益细菌数量的基因类型。综上所述，这项研究计划将为我们目前对根际植物-微生物相互作用的理解增加相当多的新知识。

Besides offering mechanical support and absorbing water and nutrients from the soil, plant root help to sense and respond to soil environment. Plant root often respond to biotic and/or abiotic cues by secreting a mixture of chemical compounds commonly referred to as root exudates. One group of organisms that interact with plant roots in the rhizosphere (the soil zone extending to a few millimeters immediately surrounding the root) is bacteria, a group consisting of both pathogenic and beneficial forms. Chemical components present in the root exudates affect the growth and physiology of bacteria, implying a dynamic interaction between rhizosphere bacteria and the plant root. The chemical components and the biological functions of the root exudates on pathogenic and beneficial root-bacteria interaction, and the genetic basis of the interactions are largely unknown. The proposed research program will use the existing vast genetic resource of Arabidopsis thaliana to identify components in the root exudates that promote colonization by beneficial Pseudomonas putida and those that repel pathogenic Pseduomonas syringae pv tomato DC3000. Furthermore, this program will unravel the genetic basis of root-microbe interactions. In the short term, chemical analysis of root exudates and associated gene expression will lead to the development of metabolic and molecular markers that could be used to identify genotypes that selectively encourage the population of beneficial bacteria in the rhizosphere. Taken together, this research program will add considerable new knowledge to our current understanding of rhizosphere plant-microbe interactions.