Fig. 1.

Plasma membrane responses of V. faba guard cells in intact plants to ABA and light. (A) Reversible changes in the free-running membrane potential of a guard cell exposed to ABA and darkness. Note that K⁺ conductances in A and B were eliminated with Ba²⁺ in the external solution and Cs⁺ in the pipette. (B) Dependence of ABA-induced anion channel activation on the plasma membrane potential. ABA (20 μM) was applied with repetitive pulses of 40 s (black squares above the trace) to a single guard cell at three holding potentials (lower trace).