Differential response of NADP-dehydrogenases and carbon metabolism in leaves and roots of two durum wheat (Triticum durum Desf.) cultivars (Karim and Azizi) with different sensitivities to salt stress.

Wheat (Triticum durum Desf.) is a common Mediterranean species of considerable agronomic importance. Salinity is one of the major threats to sustainable agricultural production mainly because it limits plant productivity.

Redox and nitric oxide homeostasis are affected in tomato (Solanum lycopersicum) roots under salinity-induced oxidative stress.

The nicotinamide adenine dinucleotide phosphate (NADPH) and reduced glutathione (GSH) molecules play important roles in the redox homeostasis of plant cells. Using tomato (Solanum lycopersicum) plants grown with 120mM NaCl, we studied the redox state of NADPH and GSH as well as ascorbate, nitric oxide (NO) and S-nitrosoglutathione (GSNO) content and the activity of the principal enzymes involved in the metabolism of these molecules in roots. Salinity caused a significant reduction in growth parameters and an increase in oxidative parameters such as lipid peroxidation and protein oxidation.

The role of nitrogen availability for the salt-tolerance of two different varieties of durum wheat.

Salt stress tolerance of durum wheat was assessed in control and 200 and 300 mM NaCl-exposed seed of two cultivars (BidiAP4 and Azizi). These salt treatments were accompanied by different levels of nitrate (Ca(NO3)2) added to the media (0.1, 3, 10 mM).

Expression pattern of genes encoding nitrate and ammonium assimilating enzymes in Arabidopsis thaliana exposed to short term NaCl stress.

Key steps in nitrate nutrition and assimilation were assessed over two weeks in control and 100mM NaCl-exposed Arabidopsis thaliana (Columbia) plants. The data showed that NaCl stress lowered nitrate contents in both leaves and roots. While NaCl stress decreased ammonium contents in leaves, it increased the contents in roots at the end of treatment.

Response of Arabidopsis thaliana, seedlings to cadmium in relation to ammonium availability.

This study explored the natural variability of Arabidopsis thaliana to find out its response to ammonium availability and characterize the tolerance capacity to cadmic stress under low, average or high nitrogen supplies. Growth was determined by different morphological traits and metabolic enzymes. Plant growth was inhibited by cadmium at low nitrogen regime.

Immunolocalization of H(+)-ATPase and IRT1 enzymes in N(2)-fixing common bean nodules subjected to iron deficiency.

The demand for iron in leguminous plants increases during symbiosis, as the metal is utilised for the synthesis of various Fe-containing proteins in both plant and bacteroids. However, the acquisition of this micronutrient is problematic due to its low bioavailability at physiological pH under aerobic conditions. Induction of root Fe(III)-reductase activity is necessary for Fe uptake and can be coupled to the rhizosphere acidification capacity linked to the H(+)-ATPase activity.

Ion uptake and structural modifications induced by nitrogen source in tomato (Solanum lycopersicum Mill. Cv. Ibiza F1).

Interactions between NO(3)(-) and NO(2)(-) were studied at the level of root uptake, ion translocation (NO(3)(-), NO(2)(-), K(+)), ion xylem exudates composition and inorganic cation contents (K(+), Ca(2+), Mg(2+)) using tomato seedling (Solanum lycopersicum Mill cv. Ibiza F1). Nitrite was supplied in the medium as KNO(2) (0, 0.

Metabolic changes of iron uptake in N(2)-fixing common bean nodules during iron deficiency.

Iron is an important nutrient in N(2)-fixing legume nodules. The demand for this micronutrient increases during the symbiosis establishment, where the metal is utilized for the synthesis of various iron-containing proteins in both the plant and the bacteroid. Unfortunately, in spite of its importance, iron is poorly available to plant uptake since its solubility is very low when in its oxidized form Fe(III).

An Arabidopsis mutant disrupted in ASN2 encoding asparagine synthetase 2 exhibits low salt stress tolerance.

Salt tolerance of Arabidopsis knockout mutant with T-DNA insertion in ASN2 gene encoding asparagine synthetase (AS, EC 6.3.5.

Arabidopsis GLUTATHIONE REDUCTASE1 plays a crucial role in leaf responses to intracellular hydrogen peroxide and in ensuring appropriate gene expression through both salicylic acid and jasmonic acid signaling pathways.

Glutathione is a major cellular thiol that is maintained in the reduced state by glutathione reductase (GR), which is encoded by two genes in Arabidopsis (Arabidopsis thaliana; GR1 and GR2). This study addressed the role of GR1 in hydrogen peroxide (H(2)O(2)) responses through a combined genetic, transcriptomic, and redox profiling approach. To identify the potential role of changes in glutathione status in H(2)O(2) signaling, gr1 mutants, which show a constitutive increase in oxidized glutathione (GSSG), were compared with a catalase-deficient background (cat2), in which GSSG accumulation is conditionally driven by H(2)O(2).

Cytosolic NADP-dependent isocitrate dehydrogenase contributes to redox homeostasis and the regulation of pathogen responses in Arabidopsis leaves.

Cytosolic NADP-dependent isocitrate dehydrogenase (cICDH) produces 2-oxoglutarate (2-OG) and NADPH, and is encoded by a single gene in Arabidopsis thaliana. Three allelic lines carrying T-DNA insertions in this gene showed less than 10% extractable leaf ICDH activity, but only relatively small decreases in growth compared to wild-type Col0. Metabolite profiling by gas chromatography-time of flight-mass spectrometry (GC-TOF-MS) and high-performance liquid chromatography (HPLC) revealed that loss of cICDH function produced only small effects on leaf compounds involved in carbon and nitrogen assimilation.

Tissue-specific cadmium accumulation and its effects on nitrogen metabolism in tobacco (Nicotiana tabaccum, Bureley v. Fb9).

Tobacco (Nicotiana Tabaccum, Bureley v. Fb9) seedlings were grown for 30 days on control medium, and then treated for seven days with different concentrations (0, 10, 20, 50 and 100 muM) of CdCl(2). Cadmium (Cd) was mostly accumulated in the leaves.

Changes in growth and activity of enzymes involved in nitrate reduction and ammonium assimilation in tomato seedlings in response to NaCl stress.

Background And Aims: In Tunisia, salt water is largely used for tomato irrigation. In this work, a study was made of the changes in the nitrate reduction and ammonium assimilation into amino acids in tomato seedlings under salinity in order to providee further insight into the salt effects on plant growth. Methods Ten-day-old tomatoes (Solanum lycopersicum) were subjected to 100 mm NaCl stress, and nitrogen metabolism in leaves and roots was studied.

NaCl stress effects on enzymes involved in nitrogen assimilation pathway in tomato "Lycopersicon esculentum" seedlings.

Tomato plants (Lycopersicon esculentum Mill, cv. Chibli F1) grown for 10 days on control medium were exposed to differing concentrations of NaCl (0, 25, 50, and 100mM). Increasing salinity led to a decrease of dry weight (DW) production and protein contents in the leaves and roots.

[Implication of glutamate, isocitrate and malate deshydrogenases in nitrogen assimilation in the cadmium-stressed tomato].

Tomato seedlings grown on nitric medium and treated with various cadmium concentrations (0 to 50 microM) were used. Results obtained show that cadmium remains predominantly located in the roots, which then seem to play the role of trap-organs. Increasing cadmium concentration in the medium leads particularly to a decrease in NO3- accumulation, together with a decrease in the activity of glutamine synthetase and in the quantity of plastidic isoform ARNm (GS2), and, on the contrary, to an increase of the cytosolic isoform ARNm (GS1).

Cadmium toxicity induced changes in nitrogen management in Lycopersicon esculentum leading to a metabolic safeguard through an amino acid storage strategy.

Tomato (Lycopersicon esculentum) seedlings were grown in the presence of cadmium. After 1 week of Cd treatment, a sharp decline in biomass accumulation in the leaves and roots was observed, together with a decrease in the rate of photosynthetic activity due to both Rubisco and chlorophyll degradation and stomata closure. Cadmium induced a significant decrease in nitrate content and inhibition of the activities of nitrate reductase, nitrite reductase, glutamine synthetase (GS) and ferredoxin-glutamate synthase.

[Reversibility of the effects of cadmium on the growth and nitrogen metabolism in the tomato(Lycopersicon esculentum)].

In order to better understand the effects of heavy metals on the growth of plants, we decided to perform recovering experiments by following both chemical and physiological parameters in cadmium pre-stressed tomato seedlings after cadmium had been removed from the nutrient solution. The work shows that cadmium suppression results in resumption of growth activity. The biomass of leaves and stems rose steadily.

Effects of cadmium on the co-ordination of nitrogen and carbon metabolism in bean seedlings.

The effect of cadmium (Cd) was investigated on the in vitro activities of leaf and root enzymes involved in carbon (C) and nitrogen (N) metabolism of bean (Phaseolus vulgaris L. cv. Morgane).