Effect of salinity on root-nodule conductance to the oxygen diffusion in the Cicer arietinum Mesorhizobium ciceri symbiosis

Department of Biology, Faculté des Sciences de Tunis, Tunis-Ville, Tūnis, Tunisia
Journal of Plant Physiology (Impact Factor: 2.77). 09/2007; 164(8):1028-36. DOI: 10.1016/j.jplph.2006.05.016
Source: PubMed

ABSTRACT Nodule conductance to O2 diffusion has been involved as a major factor of the inhibition of N2 fixation by soil salinity that severely reduces the production of grain legumes. In order to determine the effect of this constraint on the nodule conductance, oxygen uptake by the nodulated roots of Cicer arietinum was measured by recording the concentration of O2 as a function of pO2 in a gas-tight incubator. After germination and inoculation with the strain Mesorhizobium ciceri UPMCa7, the varieties Amdoun 1 and INRAT 93-1 were hydroponically grown in a glasshouse on 1L glass bottles filled with nutrient solution containing 25 mM NaCl. Salinity induced a marked decrease in shoot (30% versus 14%), root (43% versus 20%), and nodule biomass (100% versus 43%) for Amdoun 1 relative to INRAT 93-1. Although salinity completely prevented nodule formation in the sensitive variety Amdoun 1, nodule number and biomass were higher in the first than in the second variety in the absence of salt. This effect was associated with a significantly higher O2 uptake by nodulated root (510 versus 255 micromol O2 plant(-1)h(-1)) and nodule conductance (20 versus 5 microm s(-1)) in Amdoun 1 than in INRAT 93-1. Salinity did not significantly change the nodule conductance and nodule permeability for INRAT 93-1. Thus, the salt tolerance of this variety appears to be associated with stability in nodule conductance and the capacity to form nodules under salt constraint.

Download full-text


Available from: Mainassara Zaman-Allah, Jun 26, 2015
  • Source
    Turkish Journal of Agriculture and Forestry 01/2011; 35:205-214. · 0.91 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nitrogen nutrition of Hedysarum carnosum, a pastoral legume common in Tunisian central and southern rangelands, largely depends on atmospheric nitrogen fixation. Yet, this process is greatly affected by environmental factors such as salinity. This study aimed to characterize the tolerance limits and the physiological responses of H. carnosum to salinity under symbiotic nitrogen fixation. Salt treatment was imposed by adding NaCl at different concentrations (0, 50, 100 and 200 mM) to the nutrient solution. Na + content generally increased in the plant organs with increasing salinity in the culture medium. Especially, an excess accumulation of this cation was observed in leaves. Despite the fact that Na + accumulation decreased plant growth, both nodulation and symbiotic nitrogen fixation capacity of H. carnosum appeared to be relatively salt-tolerant, owing to the plant capacity to maintain tissue hydration, control Na + accumulation in shoots, and to conserve nodule efficiency to fix N 2 . Taken together, our findings indicate that H. carnosum is a glycophyte that can tolerate moderate salinity (100 mM), suggesting its possible utilization (i) in the improvement of soil fertility and (ii) in saline pastures, where the survival of other fodder species is critical.
    AFRICAN JOURNAL OF BIOTECHNOLOGY 12/2010; 9:7462-7469. · 0.57 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although relationships among plant, biological N 2 fixation, and response to soil and environmental conditions have received considerable coverage in the scientific literature, a comprehensive summary and interpretation of these interactions with specific emphasis are lacking. Fluctuations in pH, nutrient availability, temperature, and water status, among other factors, greatly influence the growth, survival, and metabolic activity of nitrogen fixation bacteria. The subsequent inhibition of nitrogenase would result in O 2 accumulation in the infected zones, inducing the decrease in nodule permeability. Poor nodulation of legumes in arid soils is likely due to decreases in population levels of rhizobia during the dry season. Fixation, therefore, also tends to decrease with legume age, mainly because of the concomitant increase in soil N. Calcium deficiency, with or without the confounding influence of low pH also affects attachment of rhizobia to root hairs. Rhizobia may have different tolerances to soil acidity factors than the host plant. Relatively, high-root temperature has also been shown to influence infection, N 2 -fixation ability, and legume growth. Also, root nodulation by the bacteria can be dependent on the formation of mycorrhiza.