Figure 1.

Schematic model of the signaling cascade from prey perception to digestion in Dionaea. Touching the TH (center) is converted into an AP. The predominant opinion on the ion fluxes involved, which lead to a plant AP, are shown in the upper left corner. An initial Ca²⁺ influx subsequently triggers Cl⁻ efflux-associated depolarization of the membrane potential. This depolarization is compensated by the activation of K⁺ efflux. The following repolarization is dominated by an H⁺ efflux. Finally, the original Ca²⁺, Cl⁻, and K⁺ concentrations have to be re-adjusted again. Besides showing different ion permeabilities, the involved transport proteins also exhibit diverse transport activities, kinetics, and voltage dependencies. Thus, the mediated ion fluxes show overlapping phases, which are important for the fine tuning of the AP. The touch-induced AP leads to a calcium wave in the trap and when two APs are triggered within a short time interval, the Ca²⁺ threshold value is exceeded, and the trap closes quickly. Furthermore, the electrical signal also causes an induction of the plant hormone JA. After continuous electrical stimulation, the JA signaling pathway is activated, resulting in the expression of digestive enzymes and finally in prey digestion.