Hydrophilic C terminus of Salicornia europaea vacuolar Na(+)/H(+) antiporter is necessary for its function.

Plant vacuolar Na(+)/H(+) antiporters play important roles in cellular ion homeostasis,vacuolar pH regulation and sequestration of Na(+) ions into the vacuole. Previous research showed that hydrophilic C-terminal region of Arabidopsis AtNHX1 negatively regulates the Na(+)/H(+) transporting activity. In this study, we truncated the hydrophilic C terminus of a vacuolar Na(+) /H(+) antiporter gene from Salicornia europaea (SeNHX1) to generate its derivative, SeNHX1-ΔC. Expression of SeNHX1 and SeNHX1-ΔC in yeast mutant showed that SeNHX1 significantly improved the tolerance to NaCl; however, the expression of SeNHX1-ΔC enormously decreased the tolerance to NaCl. Overall, these results suggest that the hydrophilic C-terminal region of SeNHX1 is required for Na(+)/H(+) exchanging activity of SeNHX1.