Genetic basis of sodium exclusion and sodium tolerance in yeast. A model for plants

Abstract

A yeast strain carrying disruptions in TRK1 and ENA genes was very sensitive to Na + because uptake discriminated poorly between K + and Na + , and Na + efflux was insignificant. Transformation with TRK1 and ENA1 restored discrimination, Na + efflux and Na + tolerance. Increasing external Ca 2+ increased Na + tolerance almost in the same proportion in TRK1 enal cells and in trkl ENAI cells, suggesting an unspecific effect of this cation. By using a vacuolar ATPase mutant, the role of the vacuole in Na + tolerance was also demonstrated. The yeast model of Na + exclusion and Na + tolerance may be extended to plants.