Phenotypic and genotypic characterization of inhabitant PGPR strains of Pseudomonas from apple orchards

Abstract

Aim of present research was to isolate and characterize the Pseudomonas strains phenotypically and genotypically from the rhizospheric soil of apple orchard at Maggota (Shimla district) Himachal Pradesh. Phenotypic identification of the test isolates was based on morphological, physiological and biochemical characterization of the bacteria followed by genotypic analysis using rRNA gene sequencing and RAPD-PCR analysis. The fourteen Pseudomonas sp. isolates were screened out for various plant growth promoting activities such as siderophore production, antifungal activity, phosphate solubilisation, HCN and ammonia production, production of plant growth regulators and lytic enzymes. Isolates showed production of plant growth regulators (auxins, gibberellins and cytokinins) in the range of 19.67-83.33µg/ml, 21.00-58.67 µg/ml and 12.33-43.33 µg/ml respectively. Pseudomonas strains showed phosphate solubilising activity in the range of 12.33-63.33 Pi µg/ml, 53.66-93.44 % SU siderophore production and 11.33-96.33mm (diameter) protease activity in plate assay. Five Pseudomonas isolates i.e. An-16-kul, An-1 -mag, An-2-mag, An-3-mag and An-6-mag showed maximum antifungal activity against plant pathogenic fungi. Therefore, the aim of present investigation was to study multifarious plant growth promoting qualities of Pseudomonas sp. and to select more efficient PGPR strain of fluorescent Pseudomonas sp. which can be further used as biofertilizer.