Chitinase-mediated destructive antagonistic potential of Pseudomonas aeruginosa GRC1 against Sclerotinia sclerotiorum causing stem rot of peanut

Pseudomonas aeruginosa GRC(1) exhibited strong antagonistic activity against Sclerotinia sclerotiorum, in vitro and in vivo. Scanning electron microscopic (SEM) studies showed morphological abnormalities such as perforation, lysis and fragmentation of hyphae of S. sclerotiorum caused by P. aeruginosa GRC(1). This strain produced extracellular chitinase enzyme, the role of which was clearly demonstrated through Tn5 mutagenesis. Bacterization of peanut seeds with GRC(1) resulted in increased seed germination and reduced stem-rot of peanut in S. sclerotiorum-infested soil by 97%. Other vegetative and yield plant parameters such as nodules per plant, pods and grain yield per plant were enhanced with a statistical significance in comparison to control. Neomycin resistant (GRC(1)(neo+)) bacterium was a good root colonizer and frequently isolated from rhizosphere of peanut plants. These findings showed P. aeruginosa GRC(1) as a potential biocontrol agent against S. sclerotiorum.