Figure 7.

Growth and Ion Content of the nhx1 nhx2 Double Knockout Depends on K⁺ and Na⁺ in Media.

Four-week-old wild-type plants (A), (C), (E), and (G) and nhx1 nhx2 (B), (D), (F), and (H) were grown in modified Spalding media containing:

(A) and (B) 1 mM K⁺ and 1 mM Na⁺ (control), (C) and (D) 1 mM K⁺ and 30 mM Na⁺ (30Na), (E) and (F) 30 mM K⁺ and 1 mM Na⁺ (30K), and (G) and (H) 30 mM K⁺ and 30 mM Na⁺ (30K30Na).

(I) Relative shoot fresh weight (FW) (compared with control media of each genotype) of plants shown in (A) to (H). Values are the mean ± sd (n = 25 plants). Similar letters indicate no significant difference (P < 0.05) using Tukey LSD test. ***, significant difference between genotypes (P ≤ 0.01; Student's t test). Wt, wild type.

(J) Close-up image of nhx1 nhx2 shoots grown in 30 mM K⁺.

(K) Close-up image of nhx1 nhx2 showing severe root curling in 30 mM K⁺ but not 30 mM Na⁺. Arrows point to regions of profuse root curling.

(L) Ratio of leaf K⁺ and Na⁺ content. Values are the mean ± sd (n = 5). Similar letters indicate no significant difference (P < 0.05) using Tukey LSD test. ***, significant difference between genotypes (P ≤ 0.001, respectively).