Characterizing Natural Variation of Bacterial Communities Colonizing the Root-Soil Interface of Arabidopsis thaliana

Lorenz Hiltner (1904) used the term “rhizosphere” to describe the zone of soil under the influence of plant roots.  Root system architecture, exudation and nutrient uptake are among the known ways that plants modulate their physical interactions with bacteria in the rhizosphere.  These interactions may lead to mutualistic, commensal, parasitic or pathogenic relationships depending on the plant species and bacteria present in the soil.  Despite more than one hundred years of research, a full understanding of the genetic bases underlying the development of rhizosphere communities has remained elusive. Recent work by Micallef (2009) using Arabidopsis ecotypes Ler and Cvi provided evidence that both plant genotype and age influence the selection and succession of bacterial communities in the rhizosphere. Here we used terminal-restriction fragment length polymorphisms (T-RFLPs) to create fingerprints of microbial communities associated with the root-soil interface of recombinant inbred lines (RILs) of Arabidopsis.  These fingerprints identified a total of 234 unique operational taxonomic units (OTU) used in our analysis.  These data will lead to a more comprehensive understanding of the evolutionary dynamics of plant-microbe interactions as well as contribute to a better understanding of how to select desirable below-ground plant traits for use in agriculture and phytoremediation.