A new study challenges the long-held idea that water movement drives the rapid closure of Venus flytraps. Researchers instead point to quick changes in cell wall stiffness triggered by electric signals.
Venus flytraps close their traps in under a second after trigger hairs are touched twice. Scientists led by Yoël Forterre at Aix-Marseille University tested the previous theory that water shifts between cell layers cause the motion.
Measurements showed water transport across the trap takes 30 to 60 seconds, far too slow to explain the speed of closure. The team observed that the trap surface grows bumpier upon triggering, which they attribute to reduced stiffness in the outer cell walls.
Electric signals and calcium ion waves spread across the leaf within a fraction of a second after the initial touch. These signals prompt the outer epidermal cell walls to soften rapidly, releasing stored stress and allowing the trap to bend shut.
Sergey Shabala at the University of Western Australia remains unconvinced, arguing that water could move simultaneously through cells and that cell wall changes may require minutes. The findings appear in the journal Science.
