Kinematics Governing Mechanotransduction in the Sensory Hair of the Venus flytrap

Abstract

Insects fall prey to the Venus flytrap (Dionaea muscipula) when they touch the sensory hairs located on the flytrap lobes, causing sudden trap closure. The mechanical stimulus imparted by the touch produces an electrical response in the sensory cells of the trigger hair. These cells are found in a constriction near the hair base, where a notch appears around the hair’s periphery. There are mechanosensitive ion channels (MSCs) in the sensory cells that open due to a change in membrane tension; however, the kinematics behind this process is unclear. In this study, we investigate how the stimulus acts on the sensory cells by building a multi-scale hair model, using morphometric data obtained from μ-CT scans. We simulated a single-touch stimulus and evaluated the resulting cell wall stretch. Interestingly, the model showed that high stretch values are diverted away from the notch periphery and, instead, localized in the interior regions of the cell wall. We repeated our simulations for different cell shape variants to elucidate how the morphology influences the location of these high-stretch regions. Our results suggest that there is likely a higher mechanotransduction activity in these ’hotspots’, which may provide new insights into the arrangement and functioning of MSCs in the flytrap.

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

“…2 c–e) of three sensory hairs (Saikia et al. 2021 ). The material properties of the cell wall, the lever, and the podium were estimated previously via a parametric study (Saikia et al.…”

“…The material properties of the cell wall, the lever, and the podium were estimated previously via a parametric study (Saikia et al. 2021 ), and they are defined by their elastic moduli: , 8 MPa, and 16 MPa, and their Poisson’s ratios: 0.3, 0.39, and 0.47, respectively. The lumen of these cells are filled with a compressible fluid, here assumed to be water with a density and a bulk modulus of 2.1 GPa which exerts a turgor pressure of .…”

“…In our previous work (Saikia et al. 2021 ), we developed a multi-scale finite element method (FEM) model of the hair using morphometric data taken from CT images, in order to evaluate the cell wall stretch at threshold values of . Since these simulations focused primarily on the influence of morphology on the resulting cell wall stretch, we did not explore the rate-dependent effects at different values of .…”

Plant Biomechanics—A Natural Transition from Molecular to Organ Scale

“…Saikia et al [ 5 ] focused on kinematic aspects of mechanotransduction, in which mechanosensitive ion channels are involved. They studied sensory hairs of Venus flytrap ( Dionaea muscipula ), which sense touching of trap lobe surfaces by insects, which eventually leads to sudden trap closure.…”

“…They studied sensory hairs of Venus flytrap ( Dionaea muscipula ), which sense touching of trap lobe surfaces by insects, which eventually leads to sudden trap closure. Saikia et al [ 5 ] combined cutting-edge empirical analyses of structure and mechanics of sensory hairs, with modelling of hair deformation at the tissue and subcellular scales. The comprehensive 3D multiscale model, based on the finite element method (FEM), in which detailed empirical data were used as the input, allowed them to calculate local stretch of individual cell walls of the hair.…”