Iturin and Surfactin Families of Lipopeptides as Key Factors in Antagonism of Bacillus subtilis Towards Meloidogyne incognita on Gerbera jamesonii Manju P.*, Subramanian S.1 Kumaruguru Institute of Agriculture, Sakthi Nagar, Erode-638 315, Tamil Nadu, India 1Department of Nematology, Tamil Nadu Agricultural University, Coimbatore-641 003, Tamil Nadu, India *Corresponding author, E-mail: agrimanju@gmail.com
Online published on 29 August, 2017. Abstract Root-knot nematode, Meloidogyne incognita is one of the serious limiting factor for the production of gerbera in commercial polyhouses. The rhizobacterium, Bacillus subtilis produces more than two dozen lipopeptide antibiotics, hydrolytic enzymes and other secondary metabolites. The biocontrol activity of Bacillus strains against multiple plant pathogens has been widely documented. Three families of Bacillus lipopeptides (surfactins, iturins and fengycins) are the most studied for their antagonistic activity against a wide range of phytopathogens, including bacteria, fungi and nematodes. Ten antagonistic Bacillus strains viz., BG27, BG31, BG33, BG37, BG42, BG55, BG57, BG61, BG63 and BG66 were isolated from gerbera plants and tested for their nematicidal activity against M. incognita. The genomic DNA of the Bacillus strains was isolated and amplified by PCR to identify antibiotic genes. Biosynthetic gene specific primers amplified a 647 bp fragment of iturin gene from BG37, BG57, BG42, BG66, BG6l and BG33 and a 441 bp fragment of surfactin gene from BG37, BG42 and BG66. BG42, with high surfactin and iturin activity, suppressed hatching of eggs and killed second stage juveniles of the nematode in vitro. The partial 16S rDNA sequences of the isolated strains BG 37 and BG42 showed 99% identity with Bacillus subtilis and were deposited in GenBank under accession numbers KM454178 and KM588210 respectively. Top Keywords Antibiotics, iturin gene, surfactin gene, gerbera, root knot nematode. Top |