A unique inventory of ion transporters poises the Venus flytrap to fast-propagating action potentials and calcium...

Since the 19^th century, it has been known that the carnivorous Venus flytrap is electrically excitable. Nevertheless, the mechanism and the molecular entities of the flytrap action potential (AP) remain unknown. When entering the electrically excitable stage, the trap expressed a characteristic inventory of ion transporters, among which the increase in glutamate receptor GLR3.6 RNA was most pronounced. Trigger hair stimulation or glutamate application evoked an AP and a cytoplasmic Ca²⁺ transient that both propagated at the same speed from the site of induction along the entire trap lobe surface. A priming Ca²⁺ moiety entering the cytoplasm in the context of the AP was further potentiated by an organelle-localized calcium-induced calcium release (CICR)-like system prolonging the Ca²⁺ signal. While the Ca²⁺ transient persisted, SKOR K⁺ channels and AHA H⁺-ATPases repolarized the AP already. By counting the number of APs and long-lasting Ca²⁺ transients, the trap directs the different steps in the carnivorous plant's hunting cycle. VIDEO ABSTRACT.