Japanese scientists find out secret of Venus flytrap’s deadly bite

By Stephen Beech

The secret of the Venus flytrap's deadly bite has finally been revealed.

The unique touch sensor of the carnivorous plant that feeds on insects has been identified by Japanese scientists.

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 the hairs are touched twice in quick succession, they trigger the closure cascade that captures prey.

But the molecular identity of the touch sensor had remained unclear until now.

The Japanese researchers discovered 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.

To visualize the dynamics, the team engineered flytraps expressing the fluorescent calcium ion (Ca2+) indicator protein GCaMP6f and used state-of-the-art two-photon microscopy with intracellular electrical recordings.

Dr. Hiraku Suda, an Assistant Professor at Saitama University, said: “Our approach enabled us to visualize the moment a physical stimulus is converted into a biological signal in living plants."

The team observed that a "gentle bend" produces a local Ca2+ rise and a small local electrical change that remains localized.

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By contrast, a stronger bend first elicits a larger electrical change.

Once that electrical signal crosses a threshold - like a switch being flipped - it triggers an all-or-none, large electrical spike together with a Ca2+ wave.

Both signals then propagate from the hair base to the leaf blade.

The findings, published in the journal Nature Communications, indicate that a threshold‑regulated, action-potential-triggering mechanism underlies the response, similar in principle to animal nervous systems.

To further analyze the mechanism underlying the tactile sensing system, the researchers used genetic tools to create DmMSL10 knockout - or "gene-disabled" - plants and showed the role of DmMSL10 in touch sensing.

The 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.

In wild-type plants, an ant touch triggered Ca2+ waves across the trap, followed by trap closure.

In DmMSL10 knockout plants, the waves were much less frequent, and closures tended to be fewer.

Dr. Suda said, “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."

He added: “Many plant responses arise from mechanosensing - the plant’s tactile sense - so the underlying molecular mechanisms may be shared beyond the Venus flytrap.”