Figure 4.

High Ca²⁺ restores the growth of sos3 on low-K⁺ growth medium. (A) Optimal growth of wild type (•), sos1 (○), and sos3 (▪) seedlings requires different external K⁺ concentrations in the media. (B) Ca²⁺ dose-response curve of wild type (•), sos1 (○), and sos3 (▪) seedlings. The medium contained 20 μM K⁺. Media were modified from MS (see Materials and Methods). Growth measurement was similar to that in Fig. 3 except that the measurement was taken 3 days after the seedling transfer to minimize the effect of residual K⁺ and Ca²⁺ carried by the plants from MS medium. [Bars = SD (n = 15).]