Induced Inorganic Phosphate Solubilization Through N-Methyl-N´-Nitro-N-Nitrosoguanidine Treated Mutants of Pseudomonas koreensis Strain AK-1 (MTCC Number 12058) Under Polyethylene Glycol

Abstract

In the present study, a wild type and mutant strain of Pseudomonas koreensis strain AK-1 (MTCC number 12058) was used for enhanced inorganic phosphorus solubilization under drought stress. Five mutants namely AK-1a, AK-1b, AK-1c, AK-1d and AK-1e were found to solubilize inorganic phosphates more than that of wild type strain in drought stress of 0–10 % polyethylene glycol. On the basis of solubilization index on Pikovskaya agar medium the highest phosphate solubilization index was recorded by mutant strain AK-1c as compared to the wild type strain (AK-1). AK-1c gave the highest Phosphate solubilization index (7.67) at 0 % of polyethylene glycol concentration and lowest (3.6) at the 10 % of polyethylene glycol. AK-1e showed the lowest (4.85) at 0 % and 2.6 at 10 % P solubilization index among the five mutant strains while AK-1 wild type strain showed 4.12 at 0 % and 2.33 at 10 % polyethylene glycol. A highest (19.82) μg/ml at 2 % and 9.73 μg/ml at 10 % PEG inorganic phosphate was solubilized by AK-1c mutant strain which was more than that of wild type variety (17 μg/ml at 2 % and 7.5 μg/ml at 10 % PEG). In plant growth promoting experiment, mutant (AK-1c and AK-1a) bacterial treated soybean plants showed increased shoot length, root length, shoot fresh weight, root fresh weight and number of lateral roots under drought stress as compared to untreated control plants. Bacteria treated soybean plants in Murashige Scoog media showed significant increase in number of lateral roots as compared to the control.