Contribution of Sugar Transporters to Spatially Organized Colonization by Microbiota Along the Longitudinal Root Axis of Arabidopsis

Abstract

Plant roots are functionally heterogeneous in cellular architecture, transcriptome profile, metabolic state, and microbial immunity. We hypothesized that axial differentiation also impacts spatial colonization by root microbiota along the root axis. We developed two growth systems, ArtSoil and CD-Rhizotrons, to grow and then dissect Arabidopsis thaliana roots into three segments. We identified distinct root and rhizosphere bacterial communities in the segments, supporting the hypothesis of microbiota differentiation along the axis. Root metabolite profiling of each segment revealed differential metabolite enrichment and specificity. Bioinformatic analyses and GUS histochemistry indicated sugar and/or microbe-induced accumulation of SWEET2, 4, and 12 sugar uniporters. Profiling of root segments from sweet mutants showed altered endospheric root microbiota spatial organization. This work reveals the interdependency between root physiology and microbial colonization, and the contribution of SWEETs to shaping local endospheric root microbiota.

Keywords: spatial microbiota organization, SWEET sugar transporters, spatial metabolite accumulation, root microbe-metabolite interactions