Figure 4.

Comparison of salt stress responses of Arabidopsis and yeast strains ectopically expressing TsHKT1;2 and AtHKT1. A to C, Four-day-old Arabidopsis seedlings overexpressing TsHKT1;2 (TsHKT1;2-OX) or AtHKT1 (AtHKT1-OX) with a 35S-CaMV promoter, in the wild-type (WT; Col-gl1) or an AtHKT1 knockout mutant (athkt1-3) background, were transferred to salt medium (Supplemental Table S4). The photograph was taken after vertical growth for 7 d (A), and root growth was measured (B) with three independent replicates (n = 30 in each repeat). A magnified image is presented in C to show the shoot phenotype. Bars = 10 mm in A and C. D, TsHKT1;1, TsHKT1;2, and AtHKT1 were ectopically expressed in the S. cerevisiae strain AXT3K (Δena1-4-Δnha1 Δnhx1), which lacks the Na⁺ efflux system. Cells transformed with a vector control and AtKAT1 were included as negative and positive controls, respectively. Yeast cells of decimal dilution were plated on AP medium containing 1 mm K⁺ (Control) and 150 mm NaCl with 1 and 10 mm KCl, respectively. [See online article for color version of this figure.]