Saitama University and NIBB decode the Venus flytrap's "sense of touch" — Protein DmMSL10 functions as sensor

The Venus flytrap senses when an insect lands on its leaves and closes them to capture prey. While this demonstrates that plants possess something akin to a sense of touch, the mechanism remained unexplained for over 200 years. Assistant Professor Hiraku Suda, Graduate Student Hiroki Asakawa, Researcher Takuma Hagihara, Professor Masatsugu Toyota, and their colleagues from the Graduate School of Science and Engineering at Saitama University, in collaboration with the research group of Professor Mitsuyasu Hasebe from the National Institute for Basic Biology (NIBB), have revealed that the protein DmMSL10, which is activated by mechanical stimuli, functions as a tactile sensor that detects contact with insects. Toyota stated, "We want to convey, based on scientific evidence, the truth behind what might be dismissed as pseudoscience-the idea that plants may also have senses." The research was published in Nature Communications.

Venus flytrap leaves have six organs called sensory hairs, and when prey touches them, the hairs bend at a constriction near their base. At this time, in response to the contact stimulus, calcium signals and electrical signals propagate throughout the leaf. When calcium signals and electrical signals are transmitted to the leaf twice through two stimulations of the sensory hair, movement occurs. This mechanism has been studied by many researchers, including Darwin, for over 200 years since its discovery. The possibility of a contact stimulus sensor existing at the base of the sensory hairs had been suggested, but the detailed cellular-level mechanism for detecting contact stimuli were unclear.

The research group introduced a biosensor that changes brightness according to intracellular calcium ion concentration into the Venus flytrap and observed how it detects contact stimuli. For observation, they utilized the new combination of a two-photon microscope with an electrophysiological device capable of measuring electrical signals inside living organisms, constructing a system that could simultaneously observe calcium signals and electrical signals at the cellular level in Venus flytrap sensory hairs.

When the sensory hair was bent slightly to apply a weak stimulus, a calcium signal and a weak electrical signal (receptor potential) were generated; these propagated only around the cells stretched by the bending. On the other hand, when the hair was bent greatly to apply a strong stimulus, a strong electrical signal (action potential) that propagated long distances throughout the leaf was generated, and a calcium signal that propagated long distances was also generated. At this time, it was found that the sensory hair detected the angle and speed at which it was bent. Furthermore, when the cell that first generates a calcium signal when bent was removed with a laser, long-distance propagation of the calcium signal no longer occurred, indicating that this cell is necessary for long-distance calcium signaling.

Next, to clarify the molecules involved in sensing contact stimuli, the researchers knocked out the DmMSL10 gene and examined the response when the sensory hair was bent. Suda stated, "We focused on DmMSL10 because it was highly expressed in sensory hairs and was a gene encoding an ion channel." Even when applying strong stimuli that generated long-distance calcium signals and action potentials in wild-type plants, these signals did not occur in the knockout. In wild-type plants, action potentials are generated when the receptor potential exceeds a threshold, but in knockout plants, even when applying the same stimulus, the receptor potential was smaller compared with the wild-type and action potentials did not occur. These results revealed that the Venus flytrap has a mechanism similar to animal nerves, where "action potentials are generated when the receptor potential exceeds a threshold."

Furthermore, to investigate whether DmMSL10 is useful for prey detection in natural environments, they constructed a system enabling calcium imaging with an ultra-wide viewing angle of 50 square centimeters and examined whether the Venus flytrap could detect the presence of walking ants. In knockout plants, the probability of long-distance calcium signals occurring when ants touched sensory hairs was low, and there was a tendency for a low probability of capturing ants, revealing that DmMSL10 contributes to a highly sensitive detection system that does not miss even slight contact stimuli from prey.

DmMSL10 exists in many plants, and E. coli also has a homologous gene, but animals do not. The sense of touch that detects contact stimuli is known to exist in various plants, which may use a mechanism similar to the Venus flytrap. This is a major step forward in elucidating plant senses, which differ from those of animals.

Journal Information
Publication: Nature Communications
Title: MSL10 is a high-sensitivity mechanosensor in the tactile sense of the Venus flytrap
DOI: 10.1038/s41467-025-63419-w