Physiological and biochemical traits involved in the genotypic variability to salt tolerance of Tunisian Cakile maritima

Abstract

Cakile maritima (family: Brassicaceae) was collected from three provenances belonging to different bioclimatic stages (humid, semi arid and arid) in Tunisia to study their eco‐physiological and biochemical responses to salinity. Seedlings were cultivated on inert sand for 20 days under NaCl treatments (0, 100, 200, 400 mm NaCl). Plant response to salinity was provenance‐ and salt‐dependent. At 100 mm NaCl, growth parameters (leaf biomass, area, number per plant and relative growth rate) were improved in plants from Jerba (originating from arid bioclimatic stage) compared with the control, while growth was reduced in those from Tabarka (from humid area). High salt levels (400 mm NaCl) decreased the plant growth in the three provenances, but plants in Tabarka were the most salt sensitive. The relative salt tolerance of plants from Jerba and Bekalta provenances was associated with low levels of malondialdehyde as well as of electrolyte leakage and endoproteolytic activity. Salt reduced leaf hydration, the decrease in water content being dose‐dependent and more pronounced in Tabarka. Increase in salinity led to significant increase in leaf succulence and decrease in leaf water potential, especially in Jerba plants. The plants from the latter displayed the highest leaf levels of Na+ and Cl−, proline, soluble carbohydrates, soluble proteins, and polyphenols. Overall, the higher salt tolerance of plants from Jerba provenance, and to a lower extent of those from Bekalta, may be partly related to their better capacity for osmotic adjustment and to limit oxidative damage when salt‐challenged.

Regional Environmental Gradients Influence Ecophysiological Responses of Dominant Coastal Dune Plants to Changes in Local Conditions

“…These results support the hypothesis that the endogenously accumulated proline might have been contributed for ROS scavenging, having a protective effect that was manifested in a decline of lipid peroxidation, and thereby improving tolerance to seawater salinity stress. Our findings are congruent with several previous reports of positive correlations between the accumulation of proline in plants and reduced damage of proteins and membranes in several environmental stress conditions, including salinity (Alia, Saradhi, and Mohanty, 1997;Gunes et al, 2007;Hassine et al, 2008;Molinari et al, 2007;Ozden, Demirel,and Kahraman, 2009;Shevyakova, Bakulina, and Kuznetsov, 2009;Siripornadulsil et al, 2002;Wided et al, 2009;Yazici et al, 2007). A possible role for plant stress indicators such as proline and MDA accumulation levels in coastal ecological monitoring was further supported by the correlations found between those stress indicators and measures of dune topography and plant diversity previously reported as being connected to prevailing coastal dynamics Macedo et al, 2010).…”

“…Our study showed that lower levels of MDA were found in plants from foredunes submitted to prevailing transgressive dynamics, attaining the lowest value in plants harvested at the extreme transgressive Mira site. Furthermore, confirming previous reports (Hassine et al, 2008;Shevyakova, Bakulina, and Kuznetsov, 2009;Wided et al, 2009;Yazici et al, 2007), we found a significant negative correlation between the levels of proline and MDA accumulation across the surveyed sites. These results support the hypothesis that the endogenously accumulated proline might have been contributed for ROS scavenging, having a protective effect that was manifested in a decline of lipid peroxidation, and thereby improving tolerance to seawater salinity stress.…”

“…In fact, proline content attained the highest values in plants from the site representing the most extreme, chronic case of transgressive dynamics (Mira), suggesting that high concentrations of proline synthesized endogenously may have an adaptive significance regarding transgressive dynamics, supporting the hypothesis that proline accumulation is a part of the plant response to an intense stress (Fidalgo et al, 2004;Hare and Cress, 1997;Smirnoff and Stewart, 1985). A study in Cakile maritima plants growing under different bioclimatic conditions and differing in their tolerance to salinity showed that the accumulation of proline was more pronounced in plants from the highest external salt level (Wided et al, 2009), suggesting a positive role of proline in salt tolerance. Further studies in five Jerusalem artichoke ecotypes also revealed the beneficial effect of proline on plant response to seawater (Long et al, 2009).…”

“…One of the most common responses to saline environments and water deficit is the synthesis and accumulation of compatible solutes, like glycinebetaine, proline, mannitol, and sugars (Maggio et al, 2003). Proline is one of the several osmoprotectants that accumulate in plants under various stress conditions and is of utmost importance for plant adaptation during osmotic stress (Khedr et al, 2003;Matysik et al, 2002;Samaras et al, 1995;Wided et al, 2009). It is well known that overproduction of ROS induces oxidative processes, such as lipid peroxidation, and this process is considered both to be a consequence and a measure of stressinduced damage at the cellular level (Gunes et al, 2007;Jain et al, 2001).…”

Halophytes of the Mediterranean Basin—Underutilized Species with the Potential to Be Nutritious Crops in the Scenario of the Climate Change

“…This slight non-alignment may be due to the different ecotype used in their experiments. In fact, in other reports a correlation between the Cakile maritima ecotype and the response to salinity regarding growth was found [ 18 , 35 , 36 , 37 ]. However, in our work, at high levels of salinity the RGR of Cakile maritima was reduced with respect to the control (by ca.…”