Live confocal imaging of cellular touch responses upon local quantifiable mechanical stimulation in plant cells

Plant cells grow and differentiate in an ever-changing environment characterized by transient signals and stimuli. The ability of plant cells to perceive, integrate, and dynamically respond to these stimuli underpins a plant adaptation and survival. Among the plethora of complex stimuli plant cells are exposed to, several stimuli have a mechanical component, for example, wind, touch, contact with insects, penetration of pathogens, and even intrinsic mechanical stresses arising during tissue growth. Despite the presence of a load-bearing cell wall that separates cells from the environment and fixes their location within a tissue, plant cells are responsive to mechanical stimuli. However, several questions remain unanswered around how mechanical stimuli are perceived and translated into cellular responses. Here we establish a system enabling application of quantifiable localized mechanical stress while simultaneously capturing cellular responses with high spatio-temporal resolution using confocal imaging. We show that this system enables estimation of locally applied pressure and provides access to the temporal and spatial details of subcellular events in intact living tissues upon touch. We propose that observing these subcellular events at high spatiotemporal resolution and linking their dynamics to the intensity of mechanical stimuli may uncover the molecular mechanisms underlying plant cell responses to touch.