Biocontrol & functional properties of pseudomonads isolated from different ecological niches & diversity of phlD a key gene in the 2, 4-DAPG biosynthesis

2, 4-diacetylphloroglucinol (DAPG) is a broad-spectrum antibiotic exhibiting biocontrol activity against plant pathogens. 1500 strains isolated from the rhizosphere region of different ecosystems viz., agricultural fields, coastal, hills & mangroves were screened for pseudomonads using rpoD primer. 350 isolates amplifying 760bp amplicon were considered as pseudomonads positive. On screening further for phlD gene, 45 strains amplifying a 745bp amplicon were selected as DAPG positive. Of these 120 positive pseudomonads from the agriculture field have 23 DAPG positive isolates, from 42 pseudomonads strains 5 codes for DAPG from the mangrove and 152 pseudomonads 17 DAPG positives from the saline coastal ecosystems. All the DAPG positives were partially sequenced & analyzed for their genetic diversity. Antagonistic activity of pseudomonads were assayed against plant pathogens resulted in 27% suppressing M. grisea growth and 35% inhibit the growth of X. oryzae & R. solani. Isolates negative for DAPG also exhibited antagonistic activity and also isolates positive for DAPG coding strains failed to exhibit antagonistic activity against the plant pathogens. In that 55% of strains having coding genes for HCN, 37% for chitinase production, 8% for quorum sensing, 33% for biofilm formation, 15% for phosphate solubilizing, 63% for protease & 46% cellulase producers. Functional properties of pseudomonads were comparatively good in agricultural ecosystem and the role of other metabolite coding genes is in progress.