Abstract
Increment of salt stress brought about a clear enhancement of the oxidative activities in tolerant plant species. Five cultivars of flax (Linum Usitatissimum L.) Sakha-1, Sakha-2, Giza-8 (Egyptian origin), Alfa-B (Lithanian origin), and Ariane (French origin) were tested for salt stress tolerance. Plants were subjected hydroponically to sodium chloride (0.00 and 100 mM NaCl) for 21 days. Parameters of oxidative stress such as activity of antioxidant enzymes peroxidase (POD), superoxide dismutase (SOD) and ascorbate peroxidase (APX) together with lipid peroxidation were determined. Electrophoretic isozyme profiles detection and total soluble protein SDS-PAGE were used as biochemical markers for assessing plant salt tolerance.
Plant growth of Ariane was improved at 100 mM NaCl as compared to control (0.0 NaCl) whereas plant growth of Sakha-1 and Sakha-2 was decreased by 100 mM NaCl level. No response was observed on plant growth of Giza-8 and Alfa-B cultivars under salt stress. Nutrients concentration ratios were disturbed under high level of NaCl (100 mM). The relative salt tolerance of Sakha-1 and Ariane cultivars was associated with high antioxidant enzymes activity POD, SOD, and low MDA content. Salt stress caused an inhibition in the synthesis of polypeptide in the leaves of flax cultivars. In addition, electrophoretic profiles of POD and SOD showed differences under salt stress. From this study, it could be concluded that Ariane and Sakha-1 cultivars showed salt tolerance for the high capacity to limit oxidative damage by increasing their activity of antioxidant enzymes together with the low content of MDA and the decrease of Na/K concentration, which may play as a part of biochemical and physiological role involved in salt tolerance and impair the oxidative damage resulted from salinity salt stress. Ariane and Sakha-1 cultivars were found to be more tolerant to salinity salt stress.