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Natureplants

These Incredible Videos Reveal How Plants Send Distress Signals When Under Attack

author

Robin Andrews

Science & Policy Writer

clockSep 14 2018, 16:11 UTC

Modifying the plant with fluorescent light reveals its defense response in all its glory. Simon Gilroy/University of Wisconsin-Madison

Trees and plants and the like can, in fact, talk to each other, but not in the way we think of it. In the Douglas fir forests of Canada, for example, trees form symbiotic, subterranean relationships with fungi. The oldest, tallest trees give their excess sugar to the fungi, the fungi provide the trees with soil nutrients, and soon this develops into a wider network involving plenty of trees.

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One thing that this fungal network makes possible is the communication of distress signals. A new study, led by the University of Wisconsin-Madison (UWM), explores various ways in which distress signaling works.

As these spectacular videos show, flora like the mustard plant Arabidopsis is able to use a combination of specific chemicals to send out warning flares to its brethren over long distances. In this case, long distances refer to across a single plant, rather than underground in a forest – but this new Science study does highlight just how adept plants are at communicating in this way.

In fact, in some ways, their signaling methods aren’t too dissimilar from that of animals.

Looking at Arabidopsis – a plant often used in studies thanks to its well-documented genome, among other things – botanist Masatsugu Toyota, formerly of UWM but now at Saitama University, was originally studying how plants’ internal communication relays, involving calcium ions, deal with things like gravity.

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Per ScienceAlert, in order to research this, he tweaked the genes of the mustard plant that caused it to express a protein that fluoresces around the ever-changing calcium ion hotspots. As it happened, this revealed a lot more about the internal networks than he or his colleagues bargained for.


It was already known that plants use bioelectrical signals to relay information around their structures, with various signal emitters and receptors at play. Previous work suggested that glutamate, a vital neurotransmitter in animals and a compound in plenty of plants, was key here, but the specifics were hard to pin down.

Fortunately, by following the flow of calcium ions around a plant, they could track what triggers its initial release. Comparing genetically modified plants that were unable to engage in much signaling to those that could, they watched as the glowing calcium ion cascades were kickstarted by glutamate pouring out of sites of damage.

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The damage, in this case, was occasionally caused by a cabbage caterpillar. As it began chomping its way through a single leaf, it lit up; glutamate was released, and calcium streamed through newly opened ion channels streamed throughout the entire plant, warning it of the potential doom-laden fate that awaited it.

Compared to animal nerve impulses, these moved an incredibly slow pace of around 1 millimeter per second (about 0.002 miles per hour). Nevertheless, for plants, this was pretty rapid. “Within minutes, an undamaged leaf can respond to the fate of a distant leaf,” they note in their study.

Let’s be clear here: plants do not have nervous systems. The cells and structures here are very different, but it’s fair to say that they can achieve the same feat as us without requiring the same biological architecture. Now, thanks to this paper, we are able to visualize it quite clearly too.

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Co-author Simon Gilroy, a professor of botany at UWM, was clearly thrilled with the entire endeavor. In a statement, he exclaimed: “Without the imaging and seeing it all play out in front of you, it never really got driven home — man, this stuff is fast!”

So, whether it's through forests or individual plants, don't forget that trees and plants are not just photosynthesizing dullards. They're positively electric, effervescent examples of evolutionarily excellence that we're still scrambling to comprehend.


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