Vegetable associated Bacillus spp. suppress the pea (Pisum sativum L.) root rot caused by Fusarium solani

Abstract F. solani causing root rot is the most devastating pathogen of pea (P. sativum L). Biological control using plant growth promoting rhizobacteria has great potential in plant disease management. In the current study, 41 bacteria were isolated from the rhizosphere of different vegetables grown under variable cropping practices. Only two out of 41 rhizobacteria antagonized the root rot pathogen (45-65%) until the 15th day of dual culture assay. The antagonistic bacteria produced one or more of the antifungal metabolites viz siderophores (discolourization zone = 3.8mm), protease (solubilization index= 2.2-2.3), glucanases (solubilization index= 4.6-5.2) and solubilized the zinc (solubilization index= 4.0-4.6) from the insoluble ore. The antagonistic bacteria were identified as Bacillus subtilis FZV-1 and B. halotolerans FZV 34 by 16S rRNA, pta, glp F, and pyr C gene analysis. The rhizobacteria also indicated putative production of lipopeptide antibiotics surfactin and fengycin based on the presence of sfp and fen D genes. In pea inoculation assays, rhizobacteria decreased the germination time over control (4-35%) and enhanced the shoot length (29 – 64 %), root length (23- 78 %) and fresh weight (28 –70 %). The rhizobacteria also reduced the root rot severity over control (25-89 %) in the pea varieties meteor and climax. The versatile plant growth promoting potential of these strains emphasizes their potential use in the biological management of pea root rot.