Studies on characterization and role of 2,4-Diacetylphloroglucinol and Pyoluteorin produced by fluorescent Pseudomonas species in replant site of apple orchard
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Date
2015
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YSPU
Abstract
The present study focuses on characterization of secondary antifungal metabolites i.e. 2,4-
diacetylphloroglucinol and Pyoluteorin produced by fluorescent Pseudomonas sp. isolated from the
normal and replant sites of apple orcards. Six strains were isolated from the replant sites of Maggota,
Sharontha and Siao of Shimla distt. and thirteen already isolated strains of fluorescent Pseudomonas
sp. from replant sites of apple were used for screening of direct and indirect plant growth promoting
activities like antifungal, siderophores, phosphate solubilization and production of HCN, ammonia,
plant growth regulators (auxins, cytokinins and gibberellins) and lytic enzymes. Isolates Sh2r, Sh4r
and B showed 99.7%, 98.4% and 99% similarity with Pseudomonas poae DSM14936 and
Pseudomonas gessardii CIP105469 respectively. Six fungal pathogenic sp. isolated from replant sites
of apple of Shimla distt. i.e. MgF1 and MgF2 showed 99.2% and 99.1% similarity with Rosellinia
necatrix and Fusarium oxysporum, ShF1 and ShF2 showed 99.5% and 99.2% similarity with
Fusarium oxysporum and Schizophyllum commune & SiF1 and SiF2 showed 99.2% and 100%
similarity with Fusarium oxysporum and Pythium ultimum.
Optimization of media, time of incubation, temperature, pH, carbon, nitrogen and mineral
sources were done for production and extraction of antifungal metabolites i.e. 2,4- diacetylphloroglucinol & Pyoluteorin and for mass multiplication of inoculums for field trials. These metabolites were extracted with ethylacetate and identified through TLC at Rf 0.8 and 0.5 respectively. Antifungal activity, MIC and thermal stability of both these metabolites were evaluated. 2,4-diacetylphloroglucinol was further characterized through HPLC and NMR techniques. Antifungal activities of Pseudomonas sp. help in suppression of plant pathogens in soil. Antifungal activity along with other plant growth promoting activities may be the reasons for better establishment and growth promotion of replanted apple. Treatments with formulations of consortial strains were found to be more effective in growth and establishment of replanted apple. Therefore these strains can be exploited for the management of replant problem of apple.
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Keywords
bacteria, planting, fungi, productivity, biological development, diseases, apples, biochemical compounds, vegetative propagation, inorganic acid salts