Figure 7.

Inhibition of the Inward K⁺ Currents in Stomatal Guard Cells by ABA and Ca²⁺ Is Impaired in cpk8 and cat3 Mutants.

(A) Representative whole-cell recordings of inward K⁺ currents in guard cell protoplasts isolated from different materials (Col, cpk8, and cat3) with or without addition of 50 μM ABA in the bath solution. The voltage protocols, as well as time and current scale bars for the recordings, are shown inside the figure. Each trace represents the K⁺ currents at the indicated voltage.

(B) Current density-voltage curves of steady state whole-cell inward K⁺ currents in guard cell protoplasts isolated from different plant materials with or without the addition of 50 μM ABA in the bath solution. The data are derived from the recordings as shown in (A) and are presented as means ± se (Col, n = 12; cpk8, n = 11; cat3, n = 13).

(C) Representative whole-cell recordings of inward K⁺ currents in guard cell protoplasts isolated from different plant material (Col, cpk8, and cat3) with or without the addition of 2 μM free Ca²⁺ in pipette solution. The voltage protocols, as well as time and current scale bars for the recordings, are shown inside the figure. Each trace represents the K⁺ currents at the indicated voltage.

(D) Current density-voltage curves of the steady state whole-cell inward K⁺ currents in guard cell protoplasts isolated from different plant materials with or without the addition of 2 μM free Ca²⁺ in the pipette solution. The data are derived from the recordings as shown in (C) and are presented as means ± se (Col, n = 14; Col+Ca²⁺, n = 21; cpk8, n = 13; cpk8+Ca²⁺, n = 22; cat3, n = 15; cat3+Ca²⁺, n = 20).