Bacillus velezensis strain improvement to control Helminthosporium maydis causing southern corn leaf blight disease in maize

Abstract

Biocontrol agents are organisms effective against plant pathogens. In present study, random mutations were made to Bacillus velezensis (accession number KY214239) by UV irradiation and ethyl methane sulfonate (EMS) to improvethe biocontrol capacity of B. velezensis strains. Mutant strain of B. velezensis (M3) showed increased biosurfactant production. The highest crude biosurfactant production were observed for the M3 mutant followed by the M5 mutant. Mutant M3 showed the highest antagonistic activity against Helminthosporium maydis with a significant decrease in the leaf blight severity index compared with the wild-type strain. Thus, the mutated strains of B. velezensis were significantly improved with respect to their bio-control capacity. This could increase the success of B. velezensis as biocontrol agent to control southern corn leaf blight of maize. Pot experiments showed significant improvement in the growth promotion of maize and inhibition of H. maydis. Maize shoot length (107.11 cm), root length (37.6 cm), shoot fresh weight (15.8 g), and root fresh weight (4.4 g) was recorded after 45 days of sowing and shows promise for the use of B. velezensis in disease suppression in maize.