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Science: Plants Perceive, Respond Like Animals, When Attacked

SAN FRANCISCO (CBS SF) - If the ability to think, feel and respond separates humans and beasts from plants, there's new evidence that shows we are not so different, after all. In fact, when attacked, the response, whether flora or fauna is almost the same.

A team of researchers at the University of Wisconsin–Madison was looking at ways plants take in and assimilate information when they stumbled upon a major discovery. Plants actually know when they are being attacked, or eaten. They have even developed mechanisms to "respond with chemical defenses to deter herbivores and repair damaged tissue."

The findings were published in the September issue of Science in an article titled, 'Nervous system-like signaling in plant defense.'

Imagine a horse among the herd. It senses a predator lurking in the bushes. It bolts. The herd follows suit, each animal spurred by a sudden release of an amino acid called glutamate that travels through the body. The herd's survival depends on the adrenal release, or fight-or-flight response in one horse and the lightning-fast communication that ensues.

The scientists observed a similar rapid-defense in plants, that also begins with the release of glutamate, the chemical its nerve cells use to send signals to other cells. But a plant is tethered to the ground; it can't run.

These so-called 'glutamate receptors' receive the signal and set off a chain of communication to the rest of the plant. The leaf can't escape an attacking caterpillar. Instead it emits a flood of calcium ions to signal to other parts of the plant that an attack is underway. It screams, "we are wounded," via a vast network, and in a matter of seconds the plant goes into a state of defense and repair. Defense strategies may include a release of noxious gas to make its leaves less tasty. Repairing may involve long-term strategies to grow new leaves.

"For an animal that [attack] could be devastating. But for plant, the way they deal with it is they just rebuild themselves," said lead author, professor Simon Gilroy.

The researchers were able to capture the process on video.

The team genetically modified plants using the gene from jellyfish that makes them glow green. The result was an amazing show of light -- a wave of fluorescent light as the flood of calcium travels through the plant's vascular system.


The video shows a cabbage caterpillar eating the leaves of a mustard plant. A wave of calcium crosses the plant, shown by florescent light, triggering a defense response in distant leaves.

Gilroy calls this accidental discovery "the classic opportunistic randomness of science." He told Forbes the work is still in its infancy but the impact is far-reaching. Someday we could find a way to warn plants of pending attacks, and they could arm themselves in advance.

Imagine that conversation.

"Classic science," says Gilroy. "You think you found one thing and there's a thousand questions that come from it." writer, producer Jan Mabry is also executive producer Bay Sunday, Black Renaissance and host of The Bronze Report. She lives in Northern California. Follow her on Twitter @janmabr.


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