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.