Article

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

Département de Biologie, Faculté de Sciences de Tunis, Campus universitaire 1060, 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.

0 Bookmarks
 · 
108 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Symbiotic nitrogen fixation (SNF) in root nodules of grain legumes such as chickpea is a highly complex process that drastically affects the gene expression patterns of both the prokaryotic as well as eukaryotic interacting cells. A successfully established symbiotic relationship requires mutual signaling mechanisms and a continuous adaptation of the metabolism of the involed cells to varying environmental conditions. Although some of these processes are well understood today many of the molecular mechanisms underlying SNF, especially in chickpea, remain unclear. Here, we reannotated our previously published transcriptome data generated by deep SuperSAGE (Serial Analysis of Gene Expression) to the recently published draft genome of chickpea to assess the root- and nodule-specific transcriptomes of the eukaryotic host cells. The identified gene expression patterns comprise up to 71 significantly differentially expressed genes and the expression of twenty of these was validated by quantitative real-time PCR with the tissues from five independent biologica lreplicates. Many of the differentially expressed transcripts were found to encode proteins implicated in sugar metabolism, antioxidant defense as well as biotic and abiotic stress responses of the host cells, and some of them were already known to contribute to SNF in other legumes. The differentially expressed genes identified in this study represent candidates that can be used for further characterization of the complex molecular mechanisms underlying SNF in chickpea.
    Frontiers in Plant Science 07/2014; 5(325). DOI:10.3389/fpls.2014.00325 · 3.64 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Five north Tunisian native rhizobia were tested in symbiosis with ‘Coco-blanc’ variety under two phosphorus (P) supplies (P -sufficient and insoluble P (IP) at 250 μmol P plant−1. At flowering stage, responses against IP were assessed and indicated that inoculation with P.Ps.09 produced a high nodule biomass (0.12g). Similarly, P.Tb.09 produced 0.08 g nodule biomass under both P and P.Bj.09 that significantly increased nodule number under IP. Shoot biomass exhibited high dry weight with P.Tb.09 and CIAT899 (1.6 g plant−1). Inoculation with CIAT899 produced a high root biomass under both P. Analysis of a halo diameter of clear zone rounding each colony under IP indicated that P.Tb.09 has developed high halo Ø (1.7cm). These variations were associated under IP with a decrease of pH by P.Ar.09 and with increase in shoot phosphatase activity by P.Ar.09, P.Bj.09, P.OM.09 and P.Ps.09. The use of P-efficient rhizobia may constitute an adaptive mechanism against P-deficiency tolerance.
    Journal of Plant Nutrition 12/2013; DOI:10.1080/01904167.2013.872275 · 0.54 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Pot experiments were conducted under greenhouse conditions to evaluate the impacts of salinity and drought stress on the growth and symbiosis of seedlings of Acacia gerrardii subsp. negevensis. Rhizobium isolates KSA5, KSA6 and KSA8 were obtained from root nodules of Acacia ampliceps (Maslin), Acacia tortilis subsp. tortilis (Forssk.) and Leucaena leucocephala (Lam.) grown in the Dirab Valley south of Riyadh City in Saudi Arabia. The seed of Acacia gerrardii subsp. negevensis was obtained from Al Marbaa Park at Asser region South of Kingdom and planted in greenhouse of the Range and Forestry Applied Research Unit at Experimental Station of Faculty of Food and Agricultural Sciences. Tolerance to temperature, pH and salt were assessed for each isolate. The results showed that the Rhizobia isolates tolerated temperatures of up to 30°C and grew at pH 5.5 to 8.5 as well as in the presence of high concentrations of NaCl up to 2% w/v. Salinity and drought stress had negative effects on seedlings growth but even stronger negative impacts on nodulation. Under these stresses, the isolates were able to modify the nodules on the roots of A. gerrardii subsp. negevensis, but this ability declined as salinity increased and drought progressed. Rhizobium isolate KSA5 was a superior competitor in its ability to cope with these stresses compared with isolates KSA6 and KSA8. Hence, it can be concluded that inoculating seedlings with indigenous Rhizobium isolates may improve the tolerance of Acacia gerrardii subsp. negevensis seedlings to salinity and drought stress in the nursery stage.
    Journal of Food Agriculture and Environment 01/2014; 12(2):1220-1226. · 0.44 Impact Factor

Full-text

Download
111 Downloads
Available from
May 23, 2014