The Putative Plasma Membrane Na + /H + Antiporter SOS1 Controls Long-Distance Na + Transport in Plants

The salt tolerance locus SOS1 from Arabidopsis has been shown to encode a putative plasma membrane Na(+)/H(+) antiporter. In this study, we examined the tissue-specific pattern of gene expression as well as the Na(+) transport activity and subcellular localization of SOS1. When expressed in a yeast mutant deficient in endogenous Na(+) transporters, SOS1 was able to reduce Na(+) accumulation and improve salt tolerance of the mutant cells. Confocal imaging of a SOS1-green fluorescent protein fusion protein in transgenic Arabidopsis plants indicated that SOS1 is localized in the plasma membrane. Analysis of SOS1 promoter-beta-glucuronidase transgenic Arabidopsis plants revealed preferential expression of SOS1 in…