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Salt stress is a major abiotic stress that limits agricultural productivity in many regions of the world. To understand the molecular basis of the salt stress response, two wheat (Triticum durum Desf.) cultivars, Karim and Azizi, which are of agronomic significance in Tunisia, were grown under non-saline and saline conditions (100 mM). Leaves and roots of control and salt-stressed plants were harvested after 11 days of salt treatment. Karim cultivar may behave as a typical Na+ include, which compartmentalizes Na+ within the leaf cell vacuoles where it could be used as an osmoticum to lower the osmotic potential necessary for the maintenance of the plant hydric status. While, accumulation of K+ was greater in Karim cultivar compared to Azizi, in both organs, presenting an important manifestation of salinity tolerance. Significant changes in metabolism of antioxidative system were observed, with an increase in protein tyrosine nitration, which indicates that salinity stress induces a nitro-oxidative stress. [ABSTRACT FROM AUTHOR]

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. After exposing the Karim and Azizi durum wheat cultivars, which are of agronomic significance in Tunisia, to 100 mM NaCl salinity, growth parameters (dry weight and length), proline content and chlorophylls were evaluated in their leaves and roots. In addition, we analyzed glutathione content and key enzymatic activities, including phosphoenolpyruvate carboxylase (PEPC), NADP-isocitrate dehydrogenase (NADP-ICDH), NADP-malic enzyme (NADP-ME), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH), involved in the carbon metabolism and NADPH-generating system. The sensitivity index indicates that cv Karim was more tolerant to salinity than cv Azizi. This higher tolerance was corroborated at the biochemical level, as cv Karim showed a greater capacity to accumulate proline, especially in leaves, while the enzyme activities studied were differentially regulated in both organs, with NADP-ICDH being the only activity to be unaffected in all organs. In summary, the data indicate that higher levels of proline accumulation and the differential responses of some key enzymes involved in the carbon metabolism and NADPH regeneration contribute to the salinity tolerance mechanism and lead to increased biomass accumulation in cv Karim. [ABSTRACT FROM AUTHOR]