OsNHX1 functions as a Na+/H+ exchanger, it has high homology with a putative Na+/H+ exchanger in Saccharomyces cerevisiae, NHX1. OsNHX1 is 2330 bp in length with an open reading frame of 1608 bp. The deduced amino acid shares high similarity with that of NHX1 and NHE isoforms in mammals. Expression of OsNHX1 can be induced by salt stress (Fukuda et al., 1999).