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 Ca2+ concentration. This channel population might be involved in the pathway of endogenous transcellular K+ currents which are activated during pollen tube tip extension.