Biological control of Fusarium-wilt and quality improvement of Sesamum indicum cv. ST-1 using fluorescent Pseudomonas

Abstract

Seven plant growth-promoting bacterial strains (LES1-LES7) were isolated from rhizosphere of Lycoperscion esculentum Mill. (Tomato) and further screened based on colony morphology, carbon source utilization and biochemically characterized as fluorescent Pseudomonads. Among the isolates prominent strain identified as Pseudomonas aeruginosa LES4 produced maximum siderophores in vitro besides indole acetic acid, hydrocyanic acid, solubilized insoluble inorganic phosphate and secreted β-1, 3-glucanase urease and chitin solubilizing enzymes chitinase. It also exhibited a strong antagonism against Fusarium oxysporum f.sp. sesami when co-cultured on nutrient agar medium and inhibiting the growth of the pathogen by 69% after 5 days incubation at 28 ± 1°C. Sesame (Sesamum indicum L. cv. ST-1). When surface sterilized seeds bacterized with P. aeruginosa LES4 showed enhancement in seedling sprouting early vegetative growth, and increased seed yield components viz. biomass accumulation, and all other yield and quality improving components. Strain LES4 significantly reduced the wilt disease of sesame in F. oxysporum f.sp. sesami-infested soil. Moreover, Tn5 induced streptomycin resistant trans-conjugants of spontaneous tetracycline-resistant LES4 (designated LES4tetra+strep+) used to exhibit efficient rhizosphere colonization of sesame. Such properties of fluorescent P. aeruginosa LES4 prove it as a beneficial and potential microbial agent against wilt causing sesame.