Science

Plants Have A Secret Code For Signaling Danger To One Another

There’s a lot more to plants than what meets the eye. As it turns out, plants don’t just passively exist around us, but are actually teeming with activity and even communicate with each other to let the entire foliage know what goes on in their environment.

A new study just published in the journal Science uncovered that plants can feel any tactile stimuli that touch their leaves, including the imperceptible movement of a caterpillar’s tiny toes. What’s more, they have a unique system of passing on the message to other leaves, warning them when an assailant is on the prowl and alerting them to brace for an imminent attack.

“A plant injured on one leaf by a nibbling insect can alert its other leaves to begin anticipatory defense responses,” the authors wrote in their paper, documenting that this communication system uses the same kind of signals found in animal nervous systems.

This secret code that plants use to communicate distress has been revealed for the first time by an international team of scientists from Japan, the U.S., and China, who observed it under the gaze of a fluorescence microscope.

Their remarkable discovery shows that plants possess their own kind of nervous system, which allows different parts of a plant to communicate with one another — all this despite lacking a brain, reports Science Magazine.

According to Phys.org, the team was already aware that a change in one part of a plant, such as a wound, a bite from an insect, or any kind of trauma, is sensed throughout the entire body of the plant. What they didn’t know was how the information got relayed from the affected part of the plant to the undamaged ones.

“We knew there’s this systemic signaling system, and if you wound [it] in one place the rest of the plant triggers its defense responses. But we didn’t know what was behind this system,” said Simon Gilroy, a botany professor at the University of Wisconsin-Madison and senior author of the new study.

As the Inquisitr previously reported, last year Gilroy led a project aiming to investigate how plants respond to gravity. For the purpose of that experiment, Gilroy shipped hundreds of mustard plant seeds to the International Space Station to see how they grow in microgravity conditions.

The 2017 study, conducted on a small mustard plant called Arabidopsis, eventually led Gilroy to this new revelation, observed on a plant belonging to the same species.

The missing piece of the plant puzzle was provided after the team made an educated guess that the mysterious communication system involved some kind of calcium signaling. Once they decided to study how calcium levels are impacted when a plant gets eaten by an insect or cut with a blade, the enigma began to unravel.

After devising a molecular sensor that made Arabidopsis glow when calcium levels increased — genetically engineering them to light up in the face of danger — the team observed the plants through a fluorescence microscope and finally figured out how leaves whisper to each other.

Their experiment revealed that, when a leaf suffers a trauma, it releases an amino acid known as glutamate — the same chemical that allows animal nerve cells to talk to one another by traveling long distance from one cell to the next and so on.

The release of glutamate prompts the plant’s vascular system to be flooded with a calcium-based signal, which cascades through the plant’s body, traversing it in under two minutes.

This carries the information from the attacked leaf to the unharmed ones, activating defense hormones that alert distant leaves of the danger. This entire process was made visible by the mutant Arabidopsis, which grew brighter as the calcium surged through its body and propagated to all of its leaves.

“Now that they have seen the calcium wave and the role of glutamate, researchers can better monitor and — perhaps one day even manipulate — the plant’s internal communications,” notes Science Magazine.

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