Figure 6.

Initial rates of K⁺ (Rb⁺) uptake in the Arabidopsis wild type (WT) and knockout lines in genes HAK5, AKT1, and CIPK23. Seeds of Arabidopsis, the single mutants hak5, akt1, and cipk23, the double mutants hak5 akt1, akt1 cipk23, and hak5 cipk23, and the triple mutant hak5 akt1 cipk23 were germinated and grown for 30 d in K⁺-sufficient nutrient solution containing 1.4 mm K⁺. After 7 d of K⁺ starvation, plants were transferred to solutions with 50 µm Rb⁺ for 7 h, during which time, samples of external solution were taken. Rb⁺ concentrations of these samples were determined and used to calculate the rate of Rb⁺ absorption from the amount of Rb⁺ depleted in the external solution per unit of root dry weight and time. Shown are average values of at least six repetitions, and error bars denote se.