Abstract
Reed keeps Na+ concentration in shoot low even under severe saline condition. We suggested that reed specifically suppress Na+ translocation from root to shoot at shoot base. We hypothesized that Na+-specific transporter or channel in shoot-base cells recover Na+ from xylem sap. We cloned a cDNA (pcnhx1) and a part of its genomic clone from reed as a candidate for involvement in this mechanism. pcnhx1 was highly homologous to osnhx1 from rice. Southern analysis suggested that reed has more than two NHX1-like genes. pcnhx1 was expressed in shoot including shoot base and up-regulated by increasing NaCl concentration. We suggest that pcnhx1 is involved in the suppression of Na+ translocation to shoot. The function of pcnhx1 will be discussed with results of yeast complementation assays and analysis of antagonism between Na+ and other cations at shoot base.
