Sorghum rhizosphere bacteriome studies to pinpoint, isolate and assess plant beneficial bacteria

Abstract

<title>Abstract</title> <bold>Background</bold> In the intricate relationship between plants and microorganisms, plant growth-promoting bacteria (PGPB) play a vital role in the rhizosphere. This study focuses on designing synthetic bacterial consortia using key bacterial strains mapped and isolated from the sorghum rhizosphere microbiome. <bold>Results</bold> A large set of samples of the rhizosphere bacteriome of <italic>Sorghum bicolor </italic>was analyzed across various genotypes and geographical locations. We assessed the taxonomic composition and structure of the sorghum root-associated bacterial community using 16S rRNA gene amplicon profiling, identifying key taxa and core-bacterial components. A set of 321 bacterial strains was then isolated, and three multi-strain consortia were designed by combining culturable and unculturable microbiome-derived information. Subsequently, co-existence and plant-growth promoting ability of three consortia were tested both <italic>in vitro</italic> and <italic>in planta</italic>. In growth-chamber and in-field experiments demonstrated that bacterial Consortia 3 promoted plant growth in growth-chamber conditions while Consortia 1 and 2 performed better in field-plot experiments. Despite these differences, 16S rRNA gene profiling confirmed the stable colonization of the inoculated consortia in the sorghum rhizosphere without significant alterations to the overall bacterial community. <bold>Conclusions</bold> This study aims at translating microbiome knowledge into applications by designing and testing microbiome-based multi-strain bacterial consortia in promoting sorghum growth.