Host mediated microbiome engineering drought tolerance in the wheat rhizosphere. rhizosphere metagenome

By conducting artificial selection on a microbiome community using the concept referred to as host mediated microbiome engineering, we were able to select a root rhizosphere microbiome that contributed a 5-day net increase in drought avoidance. When compared to the control, the engineered rhizosphere demonstrated statistically significant increase in physiological measurements of root length, root dry weight, root surface area, relative water content, and water retention. There was a significant decreases in root:shoot biomass ratio. Results also showed that the engineered microbiome achieved its maximum effectiveness by six rounds of selection, with efficacy loss during autoclaving and 1x10-3 dilution series. To identify the taxonomic and diversity comparisons of the engineered rhizosphere microbiomes, we conducted 16s rRNA amplicon and next generation sequencing by Illumina HiSeq followed by analysis using the quantitative insights into microbial ecology (QIIME2) bioinformatic software package. Results revealed taxonomic increases in proteobacteria at the phylum level and betaproteobacteria at the class level when comparing rounds 1 to round 7. There were also significant decreases in alpha microbial diversity in round 7, divergence in speciation with beta diversity between round 1 and round 7, and changes in overall community composition. We also conducted a functional metagenome inference using the phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) bioinformatic software package, revealing increases from round 1 to round 7 in gene families associated with cell motility, cell signaling, and metabolism. Taken together, the altered root architecture, increased water retention, changes at the phylum and class level to increase in proteobacteria and betaproteobacteria, and KEGG orthologs involved in cell signaling and metabolism, We hypothesize that the EM is directly or indirectly producing signals that alter root system architecture for increased water uptake surface area exploration, while also producing biofilm that adds the humectant properties of the rhizosphere, increased water retention, and preventing root desiccation that host mediated microbiome engineering could confer a generational increase in drought avoidance through subs election of the rhizosphere using both ecological and evolutionary processes. Overall, findings from both studies improve our understanding of the ecological and evolutionary implications of plant-microbe interactions in a water deficient environment, with potential outcomes of that can be directly used for the alleviation of drought stress in turfgrass and cereal crop production.