Plant and Soil

, Volume 295, Issue 1, pp 169–178

Natural occurrence of Azospirillum brasilense in strawberry plants


    • Facultad de Agronomía y ZootecniaUniversidad Nacional de Tucumán
  • J. Motok
    • Facultad de Agronomía y ZootecniaUniversidad Nacional de Tucumán
  • M. L. Tortora
    • Facultad de Agronomía y ZootecniaUniversidad Nacional de Tucumán
  • S. M. Salazar
    • Facultad de Agronomía y ZootecniaUniversidad Nacional de Tucumán
  • J. C. Díaz-Ricci
    • Instituto Superior de Investigaciones Biológicas (UNT-CONICET), Instituto de Química Biológica “Dr. Bernabé Bloj”, Facultad de Bioquímica, Química y Farmacia, UNT
Regular Article

DOI: 10.1007/s11104-007-9273-x

Cite this article as:
Pedraza, R.O., Motok, J., Tortora, M.L. et al. Plant Soil (2007) 295: 169. doi:10.1007/s11104-007-9273-x


Azospirillum species are free-living nitrogen-fixing bacteria commonly found in soil and in association with roots of different plant species. For their capacity to stimulate growth they are known as plant growth-promoting bacteria (PGPB). In this work, we demonstrate the natural occurrence and colonization of different parts of strawberry plants by Azospirillum brasilense in the cropping area of Tucumán, Argentina. Although bacteria isolations were carried out from two strawberry cultivars, e.g., Camarosa and Pájaro, attempts were successful only with the cultivar Camarosa. Whereas different strains of Azospirillum were isolated from the root surface and inner tissues of roots and stolons of the cultivar Camarosa, we have not obtained Azospirillum isolates from the cultivar Pájaro. After microbiological and molecular characterization (ARDRA) we determined that the isolates belonged to the species A. brasilense. All isolates showed to have the capacity to fix nitrogen, to produce siderophores and indoles. Local isolates exhibited different yields of indoles production when growing in N-free NFb semisolid media supplemented or not with tryptophan (0.1 mg ml−1). This is the first report on the natural occurrence of A. brasilense in strawberry plants, especially colonizing inner tissues of stolons, as well as roots. The local isolates showed three important characteristics within the PGPB group: N2-fixation, siderophores, and indoles production.


nifD-geneN2-fixationPhytohormonesPlant growth-promoting bacteriaSiderophores

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© Springer Science+Business Media B.V. 2007