Cation/H+ exchangers OsCHX11 and OsCHX16 facilitate potassium transport under saline and saline-alkaline conditions

This study aimed to elucidate the functions of saline-alkaline inducible genes encoding OsCHX11 and OsCHX16, members of the cation/H+ exchanger (CHX) family, under different component of saline-alkaline conditions. Rice biomass under carbonate-based (50 mm Na+ with carbonates) and high-pH (50 mm Na+ without carbonates) conditions was similar, whereas higher Na+/K+ ratio was observed under carbonate-based conditions. Under carbonate-based conditions, only OsCHX16 was significantly expressed, whereas both OsCHX11 and OsCHX16 were highly expressed under high pH conditions. The yeast complementation assay showed that OsCHX11 and OsCHX16 improved the yeast growth under saline, carbonate-based, and high-pH conditions by increasing K+ concentration. Taken together, these results suggest that OsCHX11 and OsCHX16 may contribute to the K+ uptake system under saline-alkaline conditions with or without carbonates at cell level.