Saitama, Japan: Plants lack nerves, yet they can sensitively detect touch from other organisms. In the Venus flytrap, highly sensitive sensory hairs act as tactile sensing organs; when touched twice in quick succession, they initiate the closure cascade that captures prey. However, the molecular identity of the touch sensor has remained unclear.
Assistant Professor Hiraku Suda and Professor Masatsugu Toyota at Saitama University, Saitama, Japan, together with colleagues and in collaboration with the research group of Professor Mitsuyasu Hasebe at the National Institute for Basic Biology (NIBB), Okazaki, Japan, have revealed that an ion channel named DmMSL10, enriched at the base of the sensory hairs, is the key touch sensor that enables the detection of very faint prey touches. The research is scheduled to be published in Nature Communications on September 30, 2025.
To visualize Ca2+ dynamics, the team engineered flytraps expressing the fluorescent Ca2+ indicator protein GCaMP6f and used two-photon microscopy with intracellular electrical recordings. "Our approach enabled us to visualize the moment a physical stimulus is converted into a biological signal in living plants," says Suda (Figure).
The team observed that a gentle bend produces a local Ca2+ rise and a small local electrical change (receptor potential) that remains localized (Video 1). By contrast, a stronger bend first elicits a larger receptor potential. Once this electrical signal crosses a threshold—like a switch being flipped—it triggers an all-or-none, large electrical spike (action potential) together with a Ca2+ wave (Video 2). Both signals then propagate from the hair base to the leaf blade. These results indicate that a threshold‑regulated, action-potential-triggering mechanism underlies this response, similar in principle to animal nervous systems.
To further analyze the mechanism underlying this tactile sensing system, the team used genetic tools to create DmMSL10 knockout (gene-disabled) plants and demonstrated the role of DmMSL10 in touch sensing. In DmMSL10 knockout plants, stimuli that trigger action potentials and long‑range Ca2+ waves in wild-type plants elicited only subthreshold receptor potentials and local Ca2+ signals (Video 3). These findings show that DmMSL10 acts like an amplifier, boosting the initial small electrical signal until it is strong enough to trigger an action potential.
To test relevance under naturalistic conditions, the team built a small ecosystem in which ants freely walked over traps (Video 4). In wild-type plants, ant touches triggered Ca2+ waves across the trap, followed by trap closure (Video 5). In DmMSL10 knockout plants, these waves were much less frequent, and closures tended to be fewer (Video 6).
"Our findings show that DmMSL10 is a key mechanosensor for the highly sensitive sensory hairs that enable the detection of touch stimuli from even the faintest, barely grazing contacts," says Suda. "Many plant responses arise from mechanosensing—the plant's tactile sense—so the underlying molecular mechanisms may be shared beyond the Venus flytrap."
