Mechanical factors contributing to the Venus flytrap’s rate-dependent response to stimuli

Abstract

The sensory hairs of the Venus flytrap (Dionaea muscipula Ellis) detect mechanical stimuli imparted by their prey and fire bursts of electrical signals called action potentials (APs). APs are elicited when the hairs are sufficiently stimulated and two consecutive APs can trigger closure of the trap. Earlier experiments have identified thresholds for the relevant stimulus parameters, namely the angular displacement $$\theta $$ θ and angular velocity $$\omega $$ ω . However, these experiments could not trace the deformation of the trigger hair’s sensory cells, which are known to transduce the mechanical stimulus. To understand the kinematics at the cellular level, we investigate the role of two relevant mechanical phenomena: viscoelasticity and intercellular fluid transport using a multi-scale numerical model of the sensory hair. We hypothesize that the combined influence of these two phenomena and $$\omega $$ ω contribute to the flytrap’s rate-dependent response to stimuli. In this study, we firstly perform sustained deflection tests on the hair to estimate the viscoelastic material properties of the tissue. Thereafter, through simulations of hair deflection tests at different loading rates, we were able to establish a multi-scale kinematic link between $$\omega $$ ω and the cell wall stretch $$\delta $$ δ . Furthermore, we find that the rate at which $$\delta $$ δ evolves during a stimulus is also proportional to $$\omega $$ ω . This suggests that mechanosensitive ion channels, expected to be stretch-activated and localized in the plasma membrane of the sensory cells, could be additionally sensitive to the rate at which stretch is applied.

Engineering Themes in Plant Forms and Functions

“…At the same time, a simulated variant with uniform cell wall thickness predicted stretch concentrated at the constriction. This kinematic model was extended into a dynamic one, via the implementation of observed viscoelastic macroscale behavior and fluid transport within sensory cells, to demonstrate a relationship between cell wall stretch rate and angular velocity (114).…”

Shapeshifting in the Venus flytrap (Dionaea muscipula): Morphological and biomechanical adaptations and the potential costs of a failed hunting cycle

“…Each half of the bilobed trap is fitted with 3-5 specialized mechanosensory hairs, arranged in a semi-triangular shape on the inner lining of each lobe (Stuhlman, 1948;Yang et al, 2010). The trigger hairs are highly sensitive, allowing detection of motile prey as minute as ants entering the trap (Jacobson, 1965;Scherzer et al, 2019;Saikia et al, 2020Saikia et al, , 2021. Dionaea muscipula relies on haptoelectric signaling to trigger trap closure, where the mechanical stimulation of the trigger hair generates a receptor potential (RP) which in turn can elicit an action potential (AP) and associated calcium flux (Jacobson, 1965;Escalante-Pérez et al, 2011;Volkov, 2019;Scherzer et al, 2022).…”