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bioRxiv · 10.1101/193672

Isolation of phosphate solubilizing Pseudomonas strains from apple rhizosphere in the Trans Himalayan region of Himachal Pradesh, India

Sharma, R.·Pal, J.·Kaur, M.
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Abstract

Total fifteen phosphate solubilizing bacteria were isolated from rhizosphere soil of apple tree on Kings B medium belonging to genus Pseudomonas spp. They were characterized on the basis of morphological and biochemical characteristics. Preliminary selection as phosphate solubilizing bacteria were done on the basis of formation of transparent zone around the colony on Pikovskayas agar medium containing 0.5% triclcium phosphate (TCP). Maximum in vitro phosphate solubilization on Pikovskayas agar plates after 72h incubation at 28{degrees}C was shown by An-15-Mg (46 mm), whereas in case of broth, again this strain showed maximum tricalcium phosphate (TCP) solubilization (76 g/ml). The pH of each inoculated broth was recorded daily and dropped significantly (pH 7.0-3.99). All the Pseudomonas isolates were further evaluated for overall plant growth promoting traits. Greatest siderophore activity was exhibited by An-14-Mg (71.23 %SU) followed by An-15-Mg (70.12 %SU) which were statiscally at par with each other. Whereas, maximum IAA production was observed again in An-15-Mg (95 g/ml). This isolate also showed the maximum production of HCN and ammonia. 16S rDNA and phylogenetic analysis showed that strain An-15-Mg exhibits 99% level of similarity with Pseudomonas aeruginosa. Therefore, it was designated as Pseudomonas aeruginosa strain An-15-Mg. HPLC analysis showed that the Pseudomonas aeruginosa strain An-15-Mg produced maximum concentration of succinic acid, malonic, citric and malic acid with small amounts of schimic, quinic, tartaric, fumaric and lactic acids. The strain An-15-Mg possessed phosphate solubilization as major PGP trait along with different PGP traits. The potential phosphate solubilizing strain of Pseudomonas aeruginosa was reported first time as PGPR which lives in close association with apple tree without harming the plant, therefore could be used as a promising phosphate solubilizer and biofertilizer in apple crop grown in high hills of Himachal Pradesh.\n\nAuthors contributionAll authors made significant efforts towards the completion of this research work and preparation of manuscript timely. Author Ranjna Sharma has done collection of soil samples of apple tree from two districts, isolation and characterization of phosphate solubilizing Pseudomonas isolates and their screening for different PGPTs, phenotypic characteriazation, 16S rRNA analysis and statistical analysis. Author S P Singh has done HPLC analysis at their institute. Author Ankita has done sequence analysis and phylogenetic tree preparation. Author Mohinder Kaur is my mentor and generated idea regarding this work. She guided me in completing this work successfully as well as manuscript writing.

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Sharma, R., Pal, J., Kaur, M.. 2017-09-25. Isolation of phosphate solubilizing Pseudomonas strains from apple rhizosphere in the Trans Himalayan region of Himachal Pradesh, India. https://doi.org/10.1101/193672

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