Coordinate up-regulation of V-H +-ATPase and vacuolar Na +/H + antiporter as a response to NaCl treatment in a C 3 halophyte Suaeda salsa

Abstract

The strategy of Suaeda salsa adaptation to high salinity was shown in this study. Our results firstly demonstrated that Na + was a beneficial element rather than toxic ion for S. salsa plants. The biomass of S. salsa seedlings increased significantly after salt-treatment (100–400 mmol/L NaCl). Secondly, S. salsa had strong ability to accumulate Na + under saline condition. Ninety-four percent of Na + absorbed by salt-treated S. salsa plant accumulated in the shoot, especially in the leaves, and 98% of Na + in the leaves accumulated in leaf symplast. Thirdly, measurement on isolated tonoplast-enriched membrane vesicles derived from the leaves of S. salsa showed that increased V-H +-ATPase hydrolytic activity, V-H +-ATPase proton pump activity and the tonoplast Na +/H + antiport activity were found in salt-treated leaves compared with the control leaves. Up-regulation of the tonoplast Na +/H + antiport activity was due to increase of both transcription and translation. These results suggested that coordinate up-regulation of V-H +-ATPase activity and Na +/H + antiporter activity play a pivotal role in Na + sequestering into vacuoles of S. salsa.