Figure 1.

ann1 Root Plasma Membrane Lacks the OH^•-Activated Conductance.

(A) Whole-cell patch clamp recordings from wild-type (WT; Col-0) root hair apical spheroplast PM. Left: Control currents (I) elicited by step voltage (V) changes, from a representative spheroplast. Centre: I after exposure to extracellular OH^• generated by 1 mM copper and 1 mM ascorbic acid (Cu-Asc). Holding potential was 0 mV. Right: mean ± se. I-V relationships for control (open circles) and OH^• exposure (n = 6). I below the V axis is cation entry into the spheroplast.

(B) As in (A) but for ann1 (n = 6). Spheroplasts from the complemented mutant proved too fragile to patch clamp.

(C) As in (A) but for wild-type root epidermal protoplasts (n = 6).

(D) ann1 root epidermal protoplasts (n = 6).

(E) Complemented mutant ann1/ANN1 (n = 6). Bathing medium (mM): 20 CaCl₂, 0.1 KCl, 0.02 NaCl, and 5 MES-Tris, pH 5.6, adjusted to 270 mOsM with d-sorbitol. Pipette solution: 40 K-gluconate, 10 KCl, 0.4 CaCl₂, 1 mM BAPTA, and 2 MES-Tris, pH 7.2, adjusted to 270 mOsM with d-sorbitol.