Bioefficacy of antimicrobial peptide biosynthesis-gene-linked antagonistic Lysinibacillus sphaericus strains for management of bacterial plant diseases in Andaman and Nicobar Islands, India

Abstract

Aim : The present study aimed to investigate the bioefficacy of antimicrobial peptide-gene-linked antagonistic Lysinibacillus sphaericus strains isolated from Andaman and Nicobar Islands, India for controlling diseases in plants. Methodology : Bacillus spp. isolated from different niches of Andaman & Nicobar Islands were characterized for antimicrobial and PGP- traits. The identity of potential isolates was confirmed by 16SrRNA gene sequence analysis. Biocontrol potential of selected isolates against chili bacterial wilt pathogen was tested in glasshouse conditions. The antimicrobial peptide biosynthesis genes responsible for antagonistic activities ofLysinibacillus sphaericusstrains were analysedbyPCR based methods. Results : Out of fifty two isolates tested, two Lysinibacillus sphaericus strains (Ls-Agu and NS2) collected from Nicobar sea sand and chili crop rhizosphere of South Andaman Islands were found good in in-vitro antagonistic potential against important plant bacterial pathogens: Ralstonia solanacearum (solanaceous bacterial wilt) and Xanthomonas oryzae pv. oryzae (rice bacterial blight) using an agar diffusion assay. In glasshouse study, both the strains Ls-Agu and NS2 showed significant biocontrol efficacy (88.9% and 66.7%) against Ralstonia solanacearum, which causes bacterial wilt disease in chili. The antimicrobial potential of these strains were further ascertained by presence of three AMP biosynthesis genes (surfactin, bacilysin and fengycin) in both the strains through PCR amplification. Interpretation : The overall results revealed the antimicrobial peptide-gene-linked strains Ls-Agu and NS2 of L. sphaericus have ability to control bacterial plant disease under Islands conditions and the same strains could be utilized for popularization on Islands for management of the bacterialdiseases.