hkt1 mutant accumulates more Na⁺ and less K⁺ under salt-stress conditions. Ion-content was determined as described in Materials and Methods in pregerminated wild-type (Col-0) and hkt1-mutant seedlings treated with 0 (control), 10 mm CaCl₂, 150 mm NaCl or both, as indicated, for 16 h prior to seedling ejection. Data are mean values (black bar in box) ± SD (upper and lower box limit) and whiskers mark outlier values (three biological experiments, ∼40 seeds each) and different letters above the bars indicate significantly different values by Tukey's HSD post hoc test (P < 0.01).