Electrophysiological approach to examine a putative cold- and menthol-sensitive channel in the liverwort Conocephalum conicum

The mechanism of cold perception by plants is still poorly understood. It was found that temperature drop evokes changes in the activity of ion pumps and channels, which leads to plasma membrane depolarization.^1,2 The nature of the primary step of its action (alteration in membrane composition,³ transient influx of Ca²⁺ etc.,²) has not been elicited yet. Our electrophysiological experiments conducted on the liverwort Conocephalum conicum showed that its cells respond not only to sudden cooling⁴ but also to menthol, generating depolarization of the plasma membrane and action potentials (APs). Similar results are well documented in mammals; cold or “cooling compounds” including menthol cause activation of thermosenstitive channel TRPM8 permeable to Ca²⁺ and generation of AP series.⁵ TRP receptors are detected, among others, in green and brown algae. Possible existence of TRPM8-like channel-receptor in Conocephalum conicum is discussed here.Key words: action potential, cold, liverwort, menthol, thermoreceptors, voltage transient