Evaluation of biocontrol potential of Pseudomonas and Bacillus spp. against Fusarium wilt of chickpea

In this study, antagonistic effects of 6 isolates of Pseudomonas and 6 isolates of Bacillus genera isolated from rhizosphere of chickpea were evaluated against Fusarium oxysporum f. sp. ciceris as potential biocontrol agents in vitro and in vivo. Fungal inhibition tests were performed using plate assay. Each isolate were tested for the production of protease, siderophore, cyanide hydrogen, indole acetic acid, antifungal volatile and extracellular compound. Twelve isolates were selected according to their high antagonistic efficiency in in vitro which was shown as inhibition zones in the dual-culture assay. According to phenotypic properties, selected isolates were identified as Bacillus subtilis (B1, B6, B28, B40, B99, and B108), Pseudomonas putida (P9 and P10) and P. aeuroginosa (P11, P12, P66 and P112). The ability of bacterial isolates was varied in production of cyanide hydrogen, siderophore, protease and indole acetic acid (IAA). Biocontrol activity and plant growth promotion of bacterial strains were evaluated under greenhouse conditions, in which P. aeuroginosa (P10 and P12), B. subtilis (B1, B6, B28 and B99) and P. aeuroginosa (P12 and B28) provided better control (P ≤ 0.05) than untreated control (15.8-44.8%) in seed treatment and soil-inoculation, respectively. The growth parameters (plant height, fresh and dry weight of plants) were significantly increased by B28, P12 and P112 isolates in both tests compared to the untreated control. Our results indicate that PGPR improve growth parameters in this plant and can help in the biocontrol of pathogen.