Simplified synergistic rhizosphere bacterial consortia enhance the antagonistic activities against <i>Ralstonia solanacearum</i> and improve plant health

The rhizosphere microbiota plays a vital role in plant stress resistance and pathogen suppression. Bacterial wilt, caused by Ralstonia solanacearum, leads to significant economic losses in a wide variety of crops. The utilization of native microbial consortia has emerged as a promising strategy for combating this disease. In this study, we assembled a synthetic microbial consortium (Co-4) from rhizosphere bacteria with demonstrated antagonistic activity, comprising four strains of Bacillus sp., Heyndrickxia sp., Franconibacter sp., and Pseudomonas sp. Transcriptome analysis of tomato plants treated with Co-4 revealed significant alterations in gene expression, particularly in carbohydrate and energy metabolism, as well as translation processes. These changes correlated with enhancements in various plant growth traits, including height, stem thickness, biomass, leaf area, photosynthetic rate, and root development. Furthermore, two simplified consortia, SynCom1 (Bacillus, Heyndrickxia, Franconibacter) and SynCom2 (Franconibacter, Pseudomonas), exhibited augmented antagonistic properties against R. solanacearum compared to their individual constituent strains. Using SynCom2 as a model, we demonstrated that its synergistic interactions resulted in increased biofilm formation, motility, biomass production, cross-feeding interactions, and volatile organic compounds (VOC) emissions, all of which likely contribute to disease suppression and enhanced plant defense. This study highlights the potential of simplified synthetic consortia for managing bacterial wilt through cooperative microbial functions, presenting an effective and environmentally sustainable biocontrol strategy.