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

植物根系除了提供机械支撑和从土壤中吸收水分和养分外，还有助于感知和响应土壤环境。植物根通常通过分泌通常被称为根分泌物的化学化合物的混合物来响应生物和/或非生物线索。在根际（延伸到根周围几毫米的土壤区域）中与植物根部相互作用的一组生物是细菌，这组生物由致病和有益形式组成。根分泌物中的化学成分影响细菌的生长和生理，暗示根际细菌与植物根系之间存在动态的相互作用。根分泌物的化学成分和生物学功能对致病和有益的根-细菌的相互作用，以及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现有的大量拟南芥遗传资源，以确定根分泌物中的成分，促进有益的恶臭假单胞菌和那些排斥致病性Pseduomonas purigingae pv番茄DC 3000的殖民化。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，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，可用于识别选择性地促进根际有益细菌种群的基因型。总之，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.