World Journal of Microbiology and Biotechnology

, Volume 24, Issue 7, pp 1027–1035

Symbiotic effectiveness and response to mannitol-mediated osmotic stress of various chickpea–rhizobia associations

Authors

    • Laboratoire Interactions Légumineuses Microorganismes (LILM)Centre de Biotechnologie, Technopark Borj Cedria (CBBC)
  • Moez Jebara
    • Laboratoire Interactions Légumineuses Microorganismes (LILM)Centre de Biotechnologie, Technopark Borj Cedria (CBBC)
  • Adel Zitoun
    • Laboratoire Interactions Légumineuses Microorganismes (LILM)Centre de Biotechnologie, Technopark Borj Cedria (CBBC)
  • Férid Limam
    • Laboratoire Interactions Légumineuses Microorganismes (LILM)Centre de Biotechnologie, Technopark Borj Cedria (CBBC)
  • Mohamed Elarbi Aouani
    • Laboratoire Interactions Légumineuses Microorganismes (LILM)Centre de Biotechnologie, Technopark Borj Cedria (CBBC)
Original Paper

DOI: 10.1007/s11274-007-9571-8

Cite this article as:
Mhadhbi, H., Jebara, M., Zitoun, A. et al. World J Microbiol Biotechnol (2008) 24: 1027. doi:10.1007/s11274-007-9571-8

Abstract

Thirty-six symbiotic associations involving six chickpea cultivars against six rhizobial strains were evaluated for symbiotic performance and responses to osmotic stress applied by mannitol (50 mM) in aerated hydroponic cultures. Analyses in different symbioses were focused on biomass production, nodulation, nitrogen fixation, and their modulation under osmotic stress conditions, as well as expression of nodular antioxidant enzymes. Mesorhizobium ciceri reference (835) and local (CMG6) strains, as well as the local (C11) M. mediterraneum allowed the best symbiotic efficiency for all chickpea cultivars. The osmotic stress induces severe decrease ranging 30–50% in aerial biomass and 50–70% for nitrogen fixation. Nevertheless, plants inoculated with M. ciceri (835) and M. mediterraneum (C11) preserve a relatively high growth (4 g plant−1) with nitrogen-fixing activity (25 μmols h−1 plant−1). The bacterial partner was the most important factor of variance of the analysed parameters in osmotic stress or physiological conditions where it gets to 60–85%. The strains allowing the best competent symbioses were proposed for field assays. Under osmotic stress, nodular peroxidase (POX) and ascorbate peroxidase (APX) activities were significantly enhanced. The increase of POX and APX was inversely correlated with the inhibition of aerial biomass production (= 0.05) and nitrogen-fixing capacity (= 0.01), suggesting a protective role of these enzymes in nodules. Superoxide dismutase (SOD) was also activated in stressed nodules. However, the spectacular decrease in catalase (CAT) activity discounts its involvement in osmotic stress response.

Keywords

Chickpea cultivarsPeroxidasesOsmotic stressRhizobial strainSymbiotic effectiveness

Abbreviations

APX

Ascorbate peroxidase

ARA

Acetylene reduction activity

CAT

Catalase

EDTA

Ethylenediaminetetraacetic acid

PCA

Principal component analysis

POX

Guaiacol peroxidase

ROS

Reactive oxygen species

SOD

Superoxide dismutase

Copyright information

© Springer Science+Business Media B.V. 2007