Physiological and molecular evidence for Na+ and Cl− exclusion in the roots of two Suaeda salsa populations

The molecular and physiological mechanisms of salt tolerance in two Suaeda salsa populations from different saline environments were evaluated. At 300 mM NaCl, the roots of the intertidal population accumulated more Na+ and Cl− compared with the roots of the inland population, but an opposite trend was observed in the leaves and xylem sap. Non-invasive Micro-test Technology (NMT) analysis revealed that the intertidal population exhibited a higher capacity to extrude Na+ at 300 mM NaCl, compared to the inland population, and the efflux of Cl− in the roots of the intertidal population was slightly elevated compared to that in the inland population at 300 mM NaCl. Salinity increased the relative expression of SsSOS1, SsNHX1 and SsCLCc in roots in both populations, especially in the intertidal population, at 300 mM NaCl. In conclusion, roots of the intertidal population had a higher capacity for Na+ and Cl− exclusion than roots of the inland population, and the SsSOS1, SsNHX1 and SsCLCc genes may be associated to this process. These characteristics may explain why the intertidal population of S. salsa thrives in high saline environments.