Biology and Fertility of Soils

, Volume 46, Issue 1, pp 17–26 | Cite as

Alleviation of drought stress effects in sunflower seedlings by the exopolysaccharides producing Pseudomonas putida strain GAP-P45

  • V. Sandhya
  • Ali SK. Z.
  • Minakshi GroverEmail author
  • Gopal Reddy
  • B. Venkateswarlu
Original Paper


Production of exopolysaccharides (EPS) can be used as a criteria for the isolation of stress tolerant microorganisms. In the present study, EPS-producing fluorescent pseudomonads were isolated from alfisols, vertisols, inseptisols, oxisols, and aridisols of different semiarid millet growing regions of India and were screened in vitro for drought tolerance in trypticase soy broth supplemented with different concentrations of polyethylene glycol (PEG6000). Out of the total 81 isolates, 26 could tolerate maximum level of stress (−0.73 MPa) and were monitored for the amount of EPS produced under maximum level of water stress. The strain GAP-P45, isolated from alfisol of sunflower rhizosphere, showed the highest level of EPS production under water stress conditions, was identified as Pseudomonas putida on the basis of 16S rDNA sequence analysis, and was used as seed treatment to study its effect in alleviating drought stress effects in sunflower seedlings. Inoculation of Pseudomonas sp. strain GAP-P45 increased the survival, plant biomass, and root adhering soil/root tissue ratio of sunflower seedlings subjected to drought stress. The inoculated bacteria could efficiently colonize the root adhering soil and rhizoplane and increase the percentage of stable soil aggregates. Scanning electron microscope studies showed the formation of biofilm of inoculated bacteria on the root surface and this, along with a better soil structure, might have protected the plants from the water stress.


Pseudomonas putida GAP-P45 Exopolysaccharide Drought stress Soil aggregate stability Biofilm 



The authors are grateful to Indian Council of Agricultural Research (ICAR), New Delhi, for providing the financial assistance in the form of network project on “Application of Microorganisms in Agriculture and Allied Sectors” (AMAAS).


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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • V. Sandhya
    • 1
  • Ali SK. Z.
    • 1
  • Minakshi Grover
    • 1
    Email author
  • Gopal Reddy
    • 2
  • B. Venkateswarlu
    • 1
  1. 1.Central Research Institute for Dry land AgricultureHyderabadIndia
  2. 2.Department of MicrobiologyOsmania UniversityHyderabadIndia

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