An insight from tolerance to salinity stress in halophyte Portulaca oleracea L.: Physio-morphological, biochemical and molecular responses.

Salinity represents one of the environmental conditions with adverse effects on the productivity of most crops throughout the world. The response of plants to salt stress is of great interest for research to understand the mechanism involved in tolerance to salinity and highlight insights into the improvement of salt tolerance-crops of importance. In this study, the effect of salt stress was observed in wild and cultivated populations of P. oleracea originated from Tunisia and Italy. The results showed that at various concentrations of NaCl (0 mM, 50 mM, 100 mM and 150 mM), salinity has led to changes in growth parameters marked mainly by an increase in fresh and dry biomass. Beside, one of the salinity-induced side effects corresponds to the competition of Na and K ions for potassium root transporters. Our results suggested that purslane deployed an important element of tolerance such as the transporters ability to discriminate cations. In addition, the variation of PC5S gene expression tested by semi-quantitative RT-PCR revealed that proline synthesis is important in plants adaptation in saline conditions. A correlation between the gene expression varying by population and saline concentration and the level of proline assayed on the leaves of P. oleracea was highlighted.