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How Plants Talk When We’re Not Around

Denyse O'Leary
Photo: Mimosa pudica, the "shameplant, by Suyash.dwivedi, CC BY-SA 4.0 , via Wikimedia Commons.

One genuine 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.

Biologist Peter Rogers pointed out recently that the similarities may shed a bit of light on issues around anaesthesia. Surprisingly, it is possible to anesthetize a plant. The shameplant (Mimosa pudica) demonstrated that:

Thirty years after anesthesia debuted in the operating room, Claude Bernard, a French physiologist, demonstrated that the shameplant (Mimosa pudica), which bashfully folds into itself when touched, was unresponsive to touch after exposure to ether, a commonly used anesthetic. The plant also folds into itself at night time, but this movement was not affected by anesthesia. Bernard concluded that anesthesia does not inhibit the ability to move; rather, it inhibits the plant’s ability to sense its environment. That is to say, anesthesia blocks consciousness…

PETER ROGERS, “HOW VENUS FLYTRAPS GIVE SCIENTISTS INSIGHTS ON CONSCIOUSNESS AND ANESTHESIA” AT BIG THINK (MARCH 27, 2022)

This Won’t Hurt a Bit

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

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

To test this, Hedrich determined if anesthetized flytraps still release signaling molecules. They found that sensory hair still released the signal molecule when stimulated, but the signal did not spread throughout the trap. In an animal, this is similar to local pain receptors detecting pain and releasing local pain signals, but those signals never reaching the brain.

The Venus flytrap’s response to anesthesia suggests that anesthesia affects the plant at cellular and organ levels, similar to animals. And this makes it a model to study general questions related to anesthesia and even consciousness. 

PETER ROGERS, “HOW VENUS FLYTRAPS GIVE SCIENTISTS INSIGHTS ON CONSCIOUSNESS AND ANESTHESIA” AT BIG THINK (MARCH 27, 2022)

Well, “consciousness” is going a little far so we’d best be clear what we mean by that. With plants, as with, say, worms, there could be an extensive communications network without any actual consciousness in the sense of an “I” in there. The effect would be roughly similar to a “smart” building, though much more complex. That is, the communications are highly sensitive and extensive, whether or not anyone is actually “home.”

How Plants Communicate

Still, the ways plants communicate are remarkable. For example, one researcher tells us that plants can use RNA to “talk to” neighbors, affecting their gene expression. It was quite an unexpected finding:

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

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

ALEJANDRA MANJARREZ, “PLANTS USE RNA TO TALK TO NEIGHBORS” AT THE SCIENTIST (OCTOBER 21, 2021)

There are also extensive plant communications via fungal networks:

Simple responses to the facts of nature aid the plant in learning; 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, those last two items are also studied in animal and human psychology.

Read the rest at Mind Matters News, published by Discovery Institute’s Bradley Center for Natural and Artificial Intelligence.