Bacterial inoculation drives microbiome-mediated resistance to a soil-borne pathogen in wheat.

Abstract

Soil microbiomes are fundamental to plant health, mediating nutrient cycling, stress tolerance, and pathogen defense. However, soil-borne pathogens such as Bipolaris sorokiniana severely constrain wheat productivity. Despite growing interest, the mechanisms by which beneficial bacterial inoculation reshapes rhizosphere microbial communities to enhance disease resistance remain poorly understood. Here, we isolated three bacterial strains, Streptomyces virginiae CMAA1738, Paenibacillus ottowii CMAA1739, and Pseudomonas inefficax CMAA1741, with antagonistic activity against B. sorokiniana, and evaluated their effects on wheat under controlled conditions. Through plant bioassays, bacterial inoculation reduced disease severity by ~60% and promoted root growth. Metataxonomic and metagenomic analyses revealed shifts in the structure and functional potential of the rhizosphere microbiome. Structural equation modeling indicated that inoculation was the primary driver of microbiome restructuring and disease suppression. Notably, inoculation restored the diversity of plant growth-promoting genes and biosynthetic gene clusters reduced by pathogen infection, enriching functions associated with stress tolerance, nutrient metabolism, and secondary metabolite production. In addition, Random Forest analysis revealed that variation in disease severity under pathogen pressure was associated with differences in bacterial community composition. Together, these findings demonstrate that bacterial inoculation can restructure the rhizosphere microbiome and restore key functional traits linked to plant resilience.