Harnessing Plant Growth-Promoting Rhizobacteria for the Biocontrol of Phytopathogens in Sustainable Agriculture: A Review

Abstract

Plant diseases significantly reduce worldwide agricultural production, causing yield declines of 21-30% for major crops, while excessive use of pesticides and chemicals poses serious health and environmental risks. Plant growth-promoting rhizobacteria (PGPR) offer an environmentally acceptable, efficient biocontrol approach against phytopathogens. Through direct mechanisms, such as the synthesis of phytohormones and nutrients, and indirect mechanisms, including the synthesis of antibiotics and siderophores and the establishment of induced systemic resistance (ISR), PGPR support plant development and suppress infections. This paper examines the role of PGPR in sustainable agriculture, focusing on their interactions with plant roots, rhizosphere dynamics, and the rhizosphere microbiome, as well as their biocontrol efficacy against fungal, bacterial, and nematode diseases. Key mechanisms include niche exclusion, competition for resources, and the release of antimicrobial compounds. Large-scale PGPR application is hindered by limitations such as inconsistent field performance, environmental acceptability concerns, and regulatory issues. Breakthroughs in microbial ecology, molecular biology, and bioinformatics offer new opportunities to optimize PGPR formulations and enhance crop-specific compatibility. Future studies should focus on developing microbial consortia, enhancing their stress tolerance, and integrating them into organic farming systems to achieve sustainable biocontrol. Within the framework of the green revolution, sustainable agriculture can increase crop yields, enhance soil health, and reduce the use of synthetic agrochemicals by leveraging PGPR-plant associations. This review highlights the promise of PGPR for the biological control of agricultural diseases and discusses the challenges and future directions for its global commercialization.