Beneficial communities from core bacterial microbiota of Oryza sativa L. soil and leaves perform dynamic role in growth promotion and suppression of bacterial leaf blight.

Abstract

Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae (Xoo), severely threatens global rice production, highlighting the urgent need for sustainable alternatives to chemical pesticides. This study investigates the rhizosphere and phyllosphere microbiomes of Oryza sativa in Punjab, Pakistan, to identify native biocontrol agents (BCAs) with potential to suppress BLB. Using 16S rRNA amplicon sequencing (V3-V9 regions), we analyzed soil and leaf samples from 10 agricultural districts. Microbial diversity, community structure, and functional potential were assessed via bioinformatics tools (QIIME 2, DADA2, PICRUSt2), with a focus on taxa antagonistic to Xoo. Healthy rhizospheres exhibited significantly higher alpha diversity (Shannon index: 6.8 vs. 4.2 in leaves; *p* < 0.001), dominated by copiotrophic taxa (Proteobacteria, Bacteroidetes) linked to organic inputs and root exudates. Diseased soils favored oligotrophic Actinobacteria and Chloroflexi. Functional metagenomics revealed enrichment of siderophore biosynthesis, antibiotic production, and nutrient-cycling genes in healthy soils. Antagonistic genera (Bacillus, Pseudomonas, Streptomyces) demonstrated chitinase and surfactin activity against Xoo, while diseased samples showed elevated Xanthomonas and Erwinia abundances correlating with BLB severity. Native BCAs outperformed non-native strains in colonization and nutrient competition, highlighting their adaptability to local agroecological conditions. Our findings position native BCAs as pivotal tools for BLB suppression and sustainable agriculture, reducing reliance on synthetic chemicals. Field trials confirmed that microbial consortia formulations reduced BLB incidence by 40% and increased yield by 18%. These findings highlight the potential of microbiome-driven strategies to mitigate BLB, reduce chemical reliance, and foster sustainable agricultural practices. Future work should integrate multi-omics approaches to optimize microbial solutions for climate resilience and scale their adoption through policy frameworks.