Functional Analysis and Genome Mining Reveal High Potential of Biocontrol and Plant Growth Promotion in Nodule-Inhabiting Bacteria Within Complex.

Bacteria belonging to the genus were frequently isolated from legume nodules. The nodule-inhabiting as a resource of biocontrol and plant growth-promoting endophytes has rarely been explored. This study explored the nodule-inhabiting ' antifungal activities and biocontrol potentials against broad-spectrum important phytopathogenic fungi. We collected strains which were isolated from nodules of , , , , , or and belong to , , , , , , or closely related to , or . These nodule-inhabiting showed diverse antagonistic activities against five phytopathogenic fungi (, , , , and ). Six strains within the complex showed broad-spectrum and potent activities against all the five pathogens, and produced multiple hydrolytic enzymes, siderophores, and lipopeptide fusaricidins. Fusaricidins are likely the key antimicrobials responsible for the broad-spectrum antifungal activities. The nodule-inhabiting strains within the complex were able to epiphytically and endophytically colonize the non-host wheat plants, produce indole acetic acids (IAA), and dissolve calcium phosphate and calcium phytate. strains RP20, RP51, and RP62 could fix N. RP51 and sp. RP31, which showed potent plant colonization and plant growth-promotion competence, effectively control fungal infection . Genome mining revealed that all strains ( = 76) within the complex contain gene encoding indole-3-pyruvate decarboxylase for biosynthesis of IAA, 96% ( = 73) contain the cluster for biosynthesis of fusaricidins, and 43% ( = 33) contain the cluster for nitrogen fixation. Together, our study highlights that endophytic strains within the complex have a high probability to be effective biocontrol agents and biofertilizers and we propose an effective approach to screen strains within the complex.