It is well known that biting animals can be put out of action with anesthetics – surprisingly, this also works with rabid plants: the famous snapping mechanism of the Venus flytrap can be stunned with ether, researchers have found. Surprising parallels emerge between the process in plants and the reactions of animals and humans. Research into the green carnivore could even have potential for medicine, say the scientists.
Normally, plants peacefully stretch their leaves into the light and their slow movements can usually only be seen through time-lapse photography. But nature also has bizarre exceptions to offer: the Venus flytrap (Dionaea muscipula) has transformed its leaf tips into claw-like traps that can catch insects in a flash. The device has a sophisticated mechanism for this: if ants and co crawl into the trap, they come into contact with sensory hairs. To trigger the snap, a prey must touch the triggers twice within 30 seconds. In this way, the plant prevents its “mouths” from tiring due to false alarms.
The scientists led by Rainer Hedrich from the University of Würzburg have been researching the fascinating mechanism of the Venus flytrap for more than ten years. They have already been able to show that plant reactions are based on electrical impulses – similar to ours. The electrical information for closing the trap is conducted through the conductive tissue instead of in nerves. “In earlier studies, we were able to show that the Venus flytrap, like humans, not only perceives touch, but can also count and remember the electrical impulses,” says Hedrich. “So it made sense to test whether and how ether affects the mechanism of the carnivorous plant,” says the researcher.
Stunned plants?
As is well known, this is a very traditional anesthetic: Ether has been used since the middle of the 19th century so that patients can better endure painful treatments or even oversleep. Surprisingly, the exact mechanism of action has never been elucidated. Even with modern anesthetics, it is often unclear how and where they work. So the researchers came up with the idea of exploring the extent to which the Venus flytrap can also be anesthetized with ether. To do this, they exposed test plants to the gas in special apparatus and carried out experiments and analyses.
The irritation of the sensory hairs in the traps during ether treatment initially documented: Similar to humans and animals, the ability of the plant to react can also be paralyzed – during the treatment the “plant mouths” no longer snapped shut. Further investigations then made it clear that the stunned traps perceived touches locally, but could not pass them on. Studies of trap memory also showed that the traps could not “remember” touches during anesthesia. This effect of the narcotic on the plant is thus also similar to that in human patients.
As the researchers explain, every time the sensory hairs in the traps are touched, the signaling substance calcium is released. This molecule also plays a crucial role in the transmission of stimuli in humans. In the course of their experiments, the researchers were able to clearly visualize the calcium signal in the plant. It was shown that the calcium signal still occurs in the sensory hairs of anesthetized plants after being touched – but it no longer leaves this touch sensor. The scientists explain that ether apparently interrupts the transmission of stimuli in the system.
Interesting parallels between humans and animals
Further test results then finally provided evidence that the blockage of a glutamate receptor is responsible for the interruption of stimulus transmission. This could also be an interesting parallel to the nervous system: These receptors perceive the neurotransmitter glutamate and are also found in humans, where they are involved in the transmission of excitation in the synapses. “We actually see calcium signals when we stimulate the traps externally with glutamate,” says co-author Manfred Heckmann. “However, this response does not occur in anesthetized traps or immature traps without the glutamate receptor.”
“Now we have to find out what the glutamate receptors of animals and plants have in common and how they differ,” says Heckmann. The team of scientists is already investigating this question. In conclusion, Scherzer says: “With this work, we show that the Venus flytrap could serve as a study object not only for plant research, but also for medicine. Perhaps it would be possible to use it to investigate the mechanism of action of drugs without having to carry out animal experiments,” says the scientist.
Source: University of Würzburg, specialist article: Scientific Reports, doi: 10.1038/s41598-022-06915-z