Saline soils are the major problem of cultivated lands of Iran. Suaeda aegyptiaca is a salt-tolerant plant (halophytes) that grow naturally in salt-affected areas of Iran. We have employed proteomics to identify the mechanisms of salt responsiveness in leaves of S. aegyptiaca grown under different salt concentrations. Ten-day-old plants were treated with 0, 150, 300, 450, and 600 mM NaCl. After 30 days of treatment, leaf samples were collected and analyzed using 2-D-PAGE. Out of 700 protein spots reproducible detected within replications, 102 spots showed significant response to salt treatment compared to 0 mM NaCl. We analyzed expression pattern of saltresponsive proteins using a hierarchical and two nonhierarchical (Fuzzy ART and SOM) statistical methods and concluded that Fuzzy ART is the superior method. Forty proteins of 12 different expression groups were analyzed using LC/MS/MS. Of these, 27 protein spots were identified including proteins involved in oxidative stress tolerance, glycinebetain synthesis, cytoskeleton remodeling, photosynthesis, ATP production, protein degradation, cyanide detoxification, and chaperone activities. The expression pattern of these proteins and their possible roles in the adaptation of S. aegyptiaca to salinity is discussed.

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In order to study the effects of salinity and silicon application on root characteristics, growth, proline content, leaf and root ion accumulation of purslane (Portulaca oleracea L.), a greenhouse experiment was conducted at Ferdowsi University of Mashhad, Iran. The experiment was carried out in a split plot design in which levels of salinity (0, 120 and 240 mM) were allocated as main plots and silicon application of 1 mM sodium silicate and no application assigned as subplots with three replications. The results indicated that salinity caused a reduction in root growth (volume, area, diameter, total and main length and root dry weight), and shoot biomass accumulation. Both root and leaf sodium (Na) content and leaf proline content increased with increasing salinity. Leaf and root potassium (K) content decreased with increasing salinity. Application of silicon improved root area, root dry weight, and leaf and root K content in the presence of salinity. It also caused a significant reduction in leaf Na content and consequently improved the K/Na ratio in leaves. Based on these results, P. oleracea has the capacity to grow in salt stress conditions and could be considered as a medicinal and vegetable for growth in harsh environments.

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