Graduate Research Assistant Kansas State University Manhattan, Kansas
Body of Abstract: The interaction of the plant roots with local soil microbes is critical in understanding plant adaptation to abiotic stress such as changes in precipitation. Our study focused on the perennial C4 grass, Andropogon gerardii (big bluestem), that dominates the tallgrass prairies of the Midwest. The broad distribution of this grass across the natural precipitation gradient (500 to 1200 mm rainfall per year) of the Great Plains in the US has resulted in distinct wet and dry ecotypes that are genetically adapted to their regional environments. We used reciprocal gardens planted with these distinct regional wet and dry Andropogon gerardii ecotypes to characterize their rhizosphere microbiomes and their potential functions. Using 16S rRNA metabarcoding sequencing, we demonstrate that while the local microbial pool is the main source of the rhizosphere communities, plants actively recruit and filter these communities. Additionally, plants had a “home field advantage” in the recruitment of microbes unique to their homesite, suggesting plant-microbe mutual recognition as well as plants’ targeted recruitment of unique microbes. These microbes may represent microbial specialists that are linked to plant stress responses. To investigate these specialists’ functional potential, we assembled 33 non-redundant Metagenome-Assembled Genomes (MAGs) representing 26 bacteria and 7 archaea from 24 dry and wet ecotype rhizosphere samples from dry and wet locations. The MAGs shared a large number of antimicrobial resistance and reactive oxygen species (ROS) protective genes that could potentially be recruited by the plant to enhance its resistance to abiotic stresses. Differential enhancement of microbial metabolic pathways provided further insights into host-microbe interactions under stressful environmental conditions. Our study facilitates a better understanding of interactions between specialist microbes and their plant hosts, aiding in predicting plant responses to abiotic stress.