Different types of electrical and calcium signals have different susceptibility to diethyl ether anaesthesia in...

Plants use electrical and Ca²⁺ signaling to trigger defence responses. The carnivorous sundew plant (Drosera) co-opted plant defence mechanisms for botanical carnivory and uses electrical and Ca²⁺ signals to capture prey in sticky tentacles. Here, using a transgenic Drosera rotundifolia transformed with a calcium sensor GCaMP6f, we visualized the propagation of electrical and Ca²⁺ signals in response to trap wounding and tentacle touch. We also tested the effect of the general volatile anaesthetic diethyl ether to inhibit these reactions. Changes in surface electrical potentials and gene expression were also investigated. Wounding induced systemic electrical and Ca²⁺ signal propagation from the local wounded to systemic traps. Touching the heads of marginal and central inner tentacles induced fast and slow Ca²⁺ signals, respectively, and only that from central inner tentacles propagated into the trap blade and entered into the neighbouring untouched tentacles. Diethyl ether completely blocked the fast systemic electrical signal propagation as well as the signal from the touched marginal tentacles, in contrast to the central inner tentacles. The marginal tentacles, however, memorized the touch and responded to it during the recovery period, indicating plant calcium memory. The study revealed at least three types of Ca²⁺ signals in the sundew plant with different susceptibility to anaesthesia, indicating different ion channel mechanisms responsible for their propagation.