The vacuolar Na+/H+antiporter geneAtNHX1has been found to improve salt tolerance in Arabidopsis and tomato through overexpression (Apse et al.1999; Zhang and Blumwald2001). AtNHX1 is similar sequence-wise with the mammalian NHE and the yeast NHX1 Na+/H+exchangers (Counillon and Pouyssegur...