Plant Growth Promotion and Stress Tolerance Enhancement through Inoculation with IBacillus proteolyticus/I OSUB18

Bacillus proteolyticus OSUB18, isolated from switchgrass, has previously been identified for its role in enhancing plant growth and suppressing diseases. In this study, its effect on the model plant, Arabidopsis thaliana, is explored. OSUB18 was found to promote the growth and health of Arabidopsis under various stress conditions. Advanced RNA-seq technology revealed changes in gene expression in plants treated with OSUB18, with the results aligning with phenotypic and metabolic observations. OSUB18 also primes Arabidopsis to effectively resist different phytopathogens and showcases strong antagonistic effects against various pathogens in vitro. In conclusion, OSUB18 boosts plant growth and health by altering root architecture, defense signaling, and reducing biotic and abiotic stresses. The isolation of B. proteolyticus OSUB18 from switchgrass unveiled its significant potential in both the enhancement of plant growth and the suppression of plant diseases in our previous study. The elucidation of the related mechanisms governing this intricate plant–microbe interaction involved the utilization of the model plant Arabidopsis thaliana. In our comprehensive study on Arabidopsis, OSUB18 treatment was found to significantly alter root architecture and enhance plant growth under various abiotic stresses. An RNA-seq analysis revealed that OSUB18 modified gene expression, notably upregulating the genes involved in glucosinolate biosynthesis and plant defense, while downregulating those related to flavonoid biosynthesis and wound response. Importantly, OSUB18 also induces systemic resistance in Arabidopsis against a spectrum of bacterial and fungal pathogens and exhibits antagonistic effects on phytopathogenic bacteria, fungi, and oomycetes, highlighting its potential as a beneficial agent in plant stress management and pathogen resistance. Overall, our findings substantiate that OSUB18 exerts a stimulatory influence on plant growth and health, potentially attributed to the remodeling of root architecture, defense signaling, and the comprehensive mitigation of various biotic and abiotic stresses.