Isolation and Comparison of Plant Growth Promoting Rhizobacteria Isolates and Consortia in Conferring Drought Tolerance in Wheat Seedlings

With changes in climate, increased world population projections, and limitations to water availability, farmers are challenged to meet future food and feed demands. This study focuses on alleviation of drought stress, by way of tolerance, in a continued effort to increase crop production in industrial agriculture. The goal of this study was to isolate and identify plant growth promoting rhizobacteria (PGPR) from a soil inoculum primed for a drought tolerant host phenotype. Two novel rhizobacteria isolates, Pseudomonas stutzeri strain A4 and Stenotrophomonas maltophilia strain C3, were shown to delay the onset of drought stress phenotypes in the aboveground tissue of TAM111 wheat seedlings after ten days of water deficit. While roots inoculated with our isolated PGPR, plus another PGPR isolated in previous studies (Enterobacter cloacae strain 16i), were shown to have a statistically significant effect of alteration in root architecture, the comparison of the treatments (single isolate vs consortia vs control) did not reveal a treatment-specific alteration of root architecture. The second portion of this study was the de novo assembly of our novel PGPR isolates with a hybrid sequencing methodology based on one next generation sequencing (NGS) platform and one third generation sequencing platform. The resulting assembly and annotation of high quality draft genomes have begun to identify the presence of bacterial genes potentially related to drought tolerance, but more likely, bacterial genes will be related to a conference of overall plant health benefits under abiotic stress conditions