K⁺ Channels in the Plasma Membrane of Lily Pollen Protoplasts

Using the patch‐clamp technique K + channels could be observed in the plasma membrane of protoplasts from pollen grains of Lilium longiflorum . With depolarizing membrane potentials the open probability of the different K + channels increased. Two K + channel populations occurring occasionally had a single channel conductance of 120 pS and 42 pS, respectively. The most often observed K + channel had a single channel conductance of 19 pS which showed an increase of channel activity with increasing free cytoplasmic Ca 2+ concentration. This channel population might be involved in the pathway of endogenous transcellular K + currents which are activated during pollen tube tip extension.