Plants Use Blazes of Light to Communicate

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Plant glows as signals are sent across its leaves. UW-Madison/YouTube

Science is just beginning to understand the subtle but intricate ways that plants — once thought of as an inert branch of life — can communicate and process information about the world around them. Now new research out of the University of Wisconsin-Madison has revealed nervous system-like mechanisms within plants that might be our most stunning look yet into the communicative world of flora.

The research was able to capture blazes of light surging through plants that operate like signals conveying information to its cells in response to stimuli. You can see this mechanism in action in the video above, which shows a glowing signal propagate like a wave across the plant, after a caterpillar chomps off one of its leaves.

Using more than a dozen of these incredible video captures, the researchers were able to reveal how glutamate, which is an abundant neurotransmitter in animals, triggers these waves of light.

"We know there's this systemic signaling system, and if you wound in one place the rest of the plant triggers its defense responses," explained Simon Gilroy, who headed the research. "But we didn't know what was behind this system."

Calcium puts on a show

What you actually see lighting up within the plant is calcium, which can carry a charge. Normally this process is not so spectacularly visible, but researchers used plants that produce a protein that only fluoresces around calcium, thus the impressive light show.

Even with the protein help, the signal happens in the blink of an eye, about one millimeter per second. That's much slower than animal nerve impulses, but it serves its purpose for plants. It also demonstrates how this process is analogous to the ways that animal nervous systems respond to stimuli.

The plants use this communication system to help prepare themselves for future threats. As the signals propagate, defense hormones kick in which can alter growth patterns.

It might officially be time to rethink our ideas of plants as immobile, unengaged, non-communicative organisms.

"Without the imaging and seeing it all play out in front of you, it never really got driven home — man, this stuff is fast!" said Gilroy.