PULLMAN, Wash. — A Washington State University study found that plants have feelings and can distinguish when touch starts and stops.
“Even without nerves, plants can sense when something touches them and when it lets go,” said researchers in a news release on Wednesday.
During the experiment, plant cells responded to the touch of a fine glass rod by sending slow waves of calcium signals to other plant cells. When the pressure was released, they sent much more rapid waves. Although scientists have known that plants can respond to touch, this study showed that plant cells send different signals when touch starts and ends, said researchers.
“It is quite surprising how finely sensitive plants cells are—that they can discriminate when something is touching them. They sense the pressure, and when it is released, they sense the drop in pressure,” said Michael Knoblauch, WSU biological sciences professor and senior author of the study in the journal Nature Plants. “It’s surprising that plants can do this in a very different way than animals, without nerve cells and at a really fine level.”
Researchers said plant cells have strong cellular walls that aren’t easily breached, unlike animal cells with more fluid membranes. Just a light touch will temporarily increase pressure in a plant cell.
“Humans and animals sense touch through sensory cells. The mechanism in plants appears to be via this increase or decrease of the internal cell pressure,” said Knoblauch. “And it doesn’t matter which cell it is. We, humans, may need nerve cells, but in plants, any cell on the surface can do this.”
Knoblauch said in future studies scientists will trigger the signal in different ways so they can understand better how touch and letting go triggers plants.
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