Cell Membrane Potentials of Higher Plants: Changes Induced by Wounding

Cell membrane potentials of cultured soybean cells, freshlycut soybean cotyledons, and freshly cut Jerusalem artichoketubers ranged from –20 to –45 mV. Readings fromthe cultured soybean cells remained within this range over aperiod of several days after the cells were subcultured. However,the membrane potentials of the soybean cotyledonary chlorenchymaand of the Jerusalem artichoke storage parenchyma exhibiteda striking hyperpolarization over a period of hours after thesetissues were sliced. The soybean cotyledons exhibited a morerapid hypopolarization than the artichoke tubers, developinga maximum average potential of –80 mV within 3 h afterwounding. These readings were obtained with the cells bathedin a complete culture medium known to permit sustained cellproliferation from soybean cotyledons. However, the wound-inducedhyperpolarization was not dependent upon any particular componentof the medium, including auxin or cytokinin. The hyperpolarizationwas observed even when cotyledon slices were incubated in isosmoticKCl.