Harnessing plant growth promoting rhizobacteria against Fusarium wilt of tomato caused by Fusarium oxysporum f.sp. lycopersici

Abstract

Abstract Fusarium wilt of tomato, caused by Fusarium oxysporum f. sp. lycopersici, is a major constraint to global production, causing up to 80% yield loss under favourable conditions. Plant growth-promoting rhizobacteria (PGPR) offer an eco-friendly alternative for disease management through growth promotion and pathogen suppression. This study aimed to isolate and characterise PGPR from tomato rhizosphere soils across different agro-climatic zones of Assam and evaluate their antagonistic potential under in vitro and glasshouse conditions. A total of 216 isolates were obtained, of which six showed strong antifungal activity (64–83% inhibition) in dual culture assays. Glasshouse evaluation revealed significant reduction in disease incidence (64.80–80.73%) over control. Molecular identification classified these isolates into Bacillus, Pseudomonas, Clostridium, Lysinibacillus, and Achromobacter. Biochemical analyses confirmed production of indole acetic acid, ammonia, siderophores, and phosphate-solubilizing compounds. These results demonstrate the potential of indigenous PGPR isolates as promising biocontrol agents for suppressing Fusarium wilt of tomato under greenhouse conditions. However, field validation and experiments including pathogen-free PGPR treatments are required to distinguish direct plant growth promotion from disease suppression before practical application.