Potassium (K⁺) is a necessary nutrient for plant growth and crop production. The K⁺ transporter plays crucial roles in the absorption and transport of K⁺ in plants. Most K⁺ transporters in Arabidopsis have been reported, but AtKUP12, which is a member of the KT/KUP/HAK family, has not yet been the subject of relevant in-depth research. In the present study, we demonstrated that AtKUP12 plays a crucial role in K⁺ uptake in Arabidopsis under 100 μM lowK⁺ and 125 mM salt stress conditions. AtKUP12 transcripts were induced by K⁺ deficiency and salt stress. We analyzed the K⁺ uptake of AtKUP12 using the K⁺ uptake-deficient yeast R5421 and Arabidopsis mutant atkup12. Transformation with AtKUP12 rescued the growth defect of mutant yeast and atkup12 mutant plants at the low-K⁺ concentration, which suggested that AtKUP12 might be involved in high-affinity K⁺ uptake in low-K⁺ environments. In comparison to the wild-type (WT) and atkup12-AtKUP12 complementation lines, atkup12 showed a dramatic reduction in potassium concentration, K⁺/Na⁺ ratio, and root and shoot growth on 12-day-old seedlings under the salt conditions; however, there was no significant difference between the complementation and WT lines. Taken together, these results demonstrate that AtKUP12 might participate in salt tolerance in Arabidopsis through K⁺ uptake and K⁺/Na⁺ homeostasis.

AtKUP12; atkup12 mutant; K⁺ uptake; K⁺/Na⁺ homeostasis; salt tolerance