Figure 4.

Auxin-induced increase in K⁺ channel density in coleoptile protoplasts. (A) In the cell-attached mode, K⁺ currents increased after the addition of 10 μM 1-NAA after a voltage step from +80 mV to −80 mV. Auxin-evoked currents (ΔI) were obtained by subtracting the mean current response (I_m) over 7 min before the addition of auxin (n = 12) from I_m collected 15 min (gray trace, n = 6) and 23 min (black trace, n = 8) after auxin treatment. With incubation times ≥23 min, auxin induces a time-dependent inward conductance. (B) Development of the K⁺-inward conductance in response to 10 μM 1-NAA. In the presence of auxin, repetitive voltage ramps (n = 14) monitor the increase in K⁺ current at times ≥15 min. In the absence of auxin only background currents were recorded (shaded area). Each trace in A and B represents the mean of n voltage ramps averaged.