Stress Tolerance and Genetic Variability of Phosphate-solubilizing Fluorescent Pseudomonas from the Cold Deserts of the Trans-Himalayas

Abstract

Nineteen efficient phosphate-solubilizing fluorescent Pseudomonas from the cold deserts of the trans-Himalayas were screened for stress tolerance against temperature, alkalinity, salinity, calcium salts, and desiccation. Phylogenetic analysis based on 16S rRNA gene sequencing placed these bacteria under three groups with fourteen strains in Group I including Pseudomonas trivialis and P. poae, two strains in Group II together with Pseudomonas kilonensis and P. corrugata, and three strains in Group III along with Pseudomonas jessenii and P. moraviensis. Genetic diversity assessed by ERIC and BOX-PCR revealed variability among strains belonging to the same phylogenetic groups. Cluster analysis based on the growth characteristics under regimes of different stress levels placed the strains into three distinct clusters displaying no correlation to their phylogenetic groups. Stress-tolerant strains differed in the level of decline in phosphate solubilization under increasing intensity of various stress parameters. The highest decrease occurred with 5% CaCO(3,) followed by 2.5% CaCO(3), pH 11, 5% NaCl, temperature of 37 degrees C, 40% PEG, 5% CaSO(4), 2.5% NaCl, 2.5% CaSO(4), pH 9 and temperature of 15 degrees C. Two strains belonging to Phylogenetic Group I exhibited higher phosphate solubilization at lower temperature. The results revealed that stress-tolerance ability was not limited to any particular phylogenetic group. Knowledge about the genetic variants of phosphate-solubilizing fluorescent Pseudomonas with potential for tolerance to desiccation, alkalinity, temperature, and salinity could be useful in understanding their ecological role under stressful environments of low phosphate availability.

Assessment of genetic diversity and plant growth promoting attributes of psychrotolerant bacteria allied with wheat (Triticum aestivum) from the northern hills zone of India

“…There are considerable populations of P-or K-solubilising bacteria in soil and in the plant rhizosphere. P-solubilising bacteria (PSB) have the ability to solubilise inorganic phosphate compounds, such as tricalcium phosphate (Vyas et al 2009). Among PGP attributes, P-solubilisation at low temperature is probably the best characterised (Gulati et al 2008;Mishra et al 2011;Selvakumar et al 2011;Yadav et al 2014a, b).…”

“…Potentially plant growth promoting bacteria (PGPB) can enhance plant resistance towards biotic and abiotic stresses (Yang et al 2009;Grover et al 2011) and improve plant growth along with soil conditions (Tilak et al 2005;Vyas et al 2009). Tolerance to stress provided by microbial inoculants becomes more significant within the perspective of crop production losses due to severe abiotic stress (Grover et al 2011).…”

“…Apart from BBDG, another group of PGPB belong to the genus Pseudomonas and in the present study isolated species of Pseudomonas identified as PGPB were Pseudomonas fluorescens, P. mediterranea, P. peli, P. fragi, P. geniculata, P. a z o t o f o r m a n s , P. s y r i n g a e P. m o r a v i e n s i s , P. extremorientalis, P. aeruginosa, P. rhodesiae and P. koreensis. It was reported earlier that Pseudomonas PGPB are highly resistant to various environmental stresses (Vyas et al 2009). …”

Diversity of Cold Tolerant Phosphate Solubilizing Microorganisms from North Western Himalayas

“…In a recent study, Vyas et al (2009) screened 19 efficient phosphate-solubilizing fluorescent Pseudomonas isolates from the cold deserts of the trans-Himalayas, for tolerance against temperature, alkalinity, salinity, calcium salts and desiccation induced stresses. Phylogenetic analysis based on 16S rRNA gene sequencing placed these bacteria under three groups with fourteen strains in Group I including Pseudomonas trivialis and P. poae, two strains in Group II together with Pseudomonas kilonensis and P. corrugata and three strains in Group III along with Pseudomonas jessenii and P. moraviensis.…”

Statistical Optimization of Medium Components for Mass Production of Plant Growth-Promoting Microbial Inoculant Pseudomonas trivialis BIHB 745 (MTCC5336)

“…Pseudomonas trivialis BIHB 745 (MTCC 5336, NCBI GenBank accession DQ536516) isolated from the Indian trans-Himalayas reported for high phosphate solubilization, stress tolerance, organic acid production, and plant growthpromotion was employed for present studies [7].…”