How plants talk when we’re not around


A real surprise in recent decades has been the discovery that plants have nervous systems like animals and use some of the same compounds in communications – for example, TMAO to relieve stress and glutamate to speed transmission.

Venus flytrap at work

Biologist Peter Rogers recently highlighted that the similarities may shed some light on anesthesia-related issues. Surprisingly, it is possible to anesthetize a plant. The shame plant (Mimosa pudica) and the Venus flytrap have been shown to:

Thirty years after the start of anesthesia in the operating room, Claude Bernard, a French physiologist, demonstrated that the shame plant (Mimosa pudica), which folds timidly in on itself when touched, no longer responded to touch after exposure to ether, a commonly used anesthetic. The plant also folds in on itself at night, but this movement was unaffected by anesthesia. Bernard concluded that anesthesia does not inhibit the ability to move; on the contrary, it inhibits the ability of the plant to sense its environment. That is to say, the anesthesia blocks consciousness…

Peter RogersHow Venus flytraps are giving scientists insight into consciousness and anesthesia” to think big (March 27, 2022)

In 2017, anesthesia was again attempted on a plant, this time the Venus flytrap:

According to [plant physiology expert Rainer] Hedrich, the Venus flytraps remember when they’re hit. When the prey lands on the plant’s trap, it brushes against a sensory hair. The hair triggers an electrical impulse and releases a wave of signal molecules through the trap. After two pulses, the trap closes and imprisons the animal prey. After five pulses, the plant produces digestive enzymes. Because anesthesia disrupts memory in animals, Hedrich theorized that anesthesia prevented the plant from remembering every stimulation.

To test this, Hedrich determined whether anesthetized flytraps still release signaling molecules. They found that the sensory hairs still released the signal molecule when stimulated, but the signal did not propagate into the trap. In an animal, this is similar to local pain receptors which detect pain and release local pain signals, but these signals never reach the brain.

The Venus flytrap’s response to anesthesia suggests that anesthesia affects the plant at the cellular and organ level, as in animals. And that makes it a model for studying general questions related to anesthesia and even consciousness.

Peter RogersHow Venus flytraps are giving scientists insight into consciousness and anesthesia” to think big (March 27, 2022)

Well, “consciousness” goes a bit far because we better understand what we mean by that. With plants, as with, say, worms, there could be a vast web of communication without any real consciousness in the sense of an “I” in there. The effect would be roughly similar to a “smart” building, although much more complex. In other words, communications are very sensitive and extensive, whether someone is actually “at home” or not.

Yet the ways in which plants communicate are remarkable. For example, a researcher tells us that plants can use RNA to “talk” to neighbors, affecting the expression of their genes, this was a rather unexpected finding:

Why would one plant need to affect the gene expression of another plant? One possibility, Perata posits, is that “sharing information by exchanging RNA would allow plants under stress to warn neighboring plants, not yet affected by stress.” Competition could be another explanation, he writes; for example, if a plant releasing miRNAs “could inhibit the physiological functions of a neighboring plant”, it could gain “a competitive advantage in resource use”. …

[Plant molecular geneticist Hailing]Jin adds that these new findings open up a lot of new questions, and there’s probably a lot more to learn about the role of RNA in plant communication. What we currently know is only the “tip of the iceberg”, she concludes.

Alejandra ManjarrezPlants use RNA to talk to neighbors” to The scientist (October 21, 2021)

There are also many plant communications via fungal networks:

Simple answers to the facts of nature help the plant learn; for example, response to the position of the sun (heliotropism)response to recent temperature changes (vernalization)losing or gaining a response to a stimulus (habituation/dishabituation)and associating one stimulus with another (associative learning). Yes, these last two items are also studied in animal and human psychology.

What about memory? Philosopher Laura Ruggles provide an example:

During the day, mallow uses the motor tissue at the base of its stems to turn its leaves towards the sun, a process actively controlled by changes in water pressure inside the plant (called turgidity). The magnitude and direction of sunlight is encoded in light-sensitive tissue, distributed over the geometric arrangement of mallow leaf veins, and stored overnight. The plant also tracks day and night cycle information via its internal circadian clocks, which are sensitive to environmental cues that signal dawn and dusk.

Overnight, using information from all of these sources, Mallow can predict where and when the Sun will rise the next day. It may not have concepts such as “the Sun” or “sunrise”, but it stores information about the light vector and day/night cycles that allow it to reorient its leaves before dawn. so that their surfaces face the Sun as it rises in the sky. It also allows it to relearn a new location when plant physiologists play with its “head” by changing the direction of the light source. When the factories are closed in the dark, the anticipatory mechanism also works offline for a few days. Like other foraging strategies, it is all about maximizing available resources – in this case, sunlight.

Laura RugglesThe spirit of plants” to infinite time (December 12, 2017)

Even if the plant is not “thinking”, it has an effective substitute for thinking in the form of chemical communication cascades. It turns out that nature is much more information-dense than we thought.

To note: One last thing: something else plants sometimes do is manipulate insect pests into killing themselves:


You can also read:

Plants help each other. Are they aware of themselves? Can they suffer? Recent discoveries that plants can do many things we thought only animals could do raise some interesting questions. Plants’ elaborate communication systems emphasize the fact that information is immaterial, but they do not involve individual consciousness.

and

How plants can count and remember without a brain. Plants like Venus Flytrap can time things due to the chemicals circulating in their systems. Although a mind is needed to work with ideas, many natural systems store information in other ways. Plants store information about their experiences.

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