Figure 3.

Al induction of anion channels in the plasma membrane of protoplasts isolated from the DTZ of the primary root of an Al-resistant and an Al-sensitive maize cultivar. From a holding potential of −52 mV, consecutive 2-s voltage pulses were applied to the plasma membrane in 20-mV steps from −132 to 88 mV. Whole-cell currents were measured in protoplasts isolated from cortical DTZ cells of intact root apices incubated for 1 h in an agarose gel (0.6%, w/v) containing NS and 0 μm (a and b) or 90 μm (c and d) Al. a and c, Al-resistant cv ATP-Y; b and d, Al-sensitive cv Lixis. The pipette solution contained 100 mm TEACl, 2 mm MgCl₂, 2 mm MgATP, 2 mm EGTA, and 10 mm HEPES/Tris (pH 7.2), and the bath solution contained 20 mm TEACl, 1 mm CaCl₂, 0.05 mm AlCl₃, and 5 mm MES/Tris (pH 4.3). e, Corresponding current-voltage relation of anion channels induced by Al treatment of maize roots in the steady state. Black circles, Al-resistant cv ATP-Y; white circles, Al-sensitive cv Lixis.