Spatial Dynamics of Rhizosphere Microbiome Across Different Scales

Abstract:

The rhizosphere is a dynamic environment involving complex interactions between the plant roots, microbial community, and the surrounding soil. Plants primarily shape their rhizosphere microbiome through the release of specific carbon compounds and metabolites called exudates into the rhizosphere environment from the roots. The transport of root exudates by the roots is thought to be spatially and temporally distinct resulting in different microbial community compositions colonizing different parts of the root over time. This spatial and temporal distribution of the rhizobiome is increasingly being recognized, but understudied. To address this, we are investigating rhizosphere microbial community structure and function from the proximal and distal parts of the primary root of Brachypodium distachyon grown in unamended natural soil from the Angelo coast range reserve using fabricated ecosystems known as the EcoFAB. Angelo reserve is a well-studied field site and metagenomic data showed statistically significant partitioning of different microbial processes across depths. Our preliminary experiments with different soil inoculums showed good reproducibility using EcoFABs and an enrichment of Actinobacteria, Deltaproteobacteria and Pedosphaerae in the rhizosphere. In this study, we compare rhizobiome assembly in EcoFABs with other conventional growth systems such as test tubes and larger pots under the same environmental conditions. From our analysis of different growth systems, we hope to establish a reduced-complexity consortium of the core rhizosphere microbiome, specific to B. distachyon grown using a specific soil source.