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We tend to view plants as helpless and passive green blobs, but a fascinating new study, in which scientists have used fluorescent light to visualize alarm signals in plants, shows how our photosynthesizer friends can mobilize their defenses .
A new study published today in Science offers an unprecedented view of the signaling action that occurs in factories when they are attacked. A second or two after an injury has been inflicted on a plant, for example a caterpillar, a warning signal emanates from the wound and extends across the entire plant in less than 120 seconds . The factory, now aware that it is under attack – or at least "conscious" of what it can be – can respond to the threat by putting in place chemical countermeasures.
Scientists have long known this signaling system, but the new study, led by researchers at the University of Wisconsin-Madison, the Japan Science and Technology Agency and several other institutions, is the first to show this mechanism remarkable defense. in action Moreover, the study offers new perspectives on the biological processes underlying this nervous system such as signaling, still poorly understood.
"We know that if you hurt a leaf, you get an electric charge, and you get a spread that travels across the plant," said botanist Simon Gilroy, professor at UWM and co-author of the new study. declaration. "What triggered this electrical charge, and how it moved through the factory, was unknown."
Gilroy and his colleague Masatsugu Toyota, who led the research, suspected calcium was a factor. Calcium ions, which produce an electrical charge, are known to perform signaling functions in factories, particularly in response to changing environmental conditions. Scientists have struggled to visualize this movement within plants, which leads to a rather fascinating solution. To watch the calcium move in real time, Toyota and its colleagues are transforming the plants into bioengineering to produce a fluorescent protein around the calcium, illuminating the interior of the plants like a Christmas tree. Using state-of-the-art microscopes and biosensors, researchers were able to track the presence and volume of calcium in response to various injuries, including crawler chomps, scissors, and crush damage.
While experimenting on mustard plants, the researchers observed the plants light up when calcium moved away from the wound and headed toward their other leaves. The signal propagated at a speed of one millimeter per second, which is fast enough to reach the farthest corners of the plant in less than two minutes. The calcium impulses may have spread while traveling through the vascular or circulatory system of the plant.
After the warning signal fully spread, the leaves began to release their defense-related hormones in anticipation of future attacks. Plants, in addition to releasing chemicals that trigger the repair process, can release chemicals that are harmful to insects.
This latest research builds on the work of Swiss scientist Ted Farmer, who previously showed that defense-related electrical signals depend on glutamate, a major neurotransmitter in mammals and a signaling agent in plants. In a secondary experiment, Toyota and colleagues have demonstrated that long-range signaling is lost in plants that have been released from glutamate release via two specific genetic mutations. This strongly suggests that glutamate, when released at the site of an injury, triggers the calcium explosion – a previously undocumented action in plants.
Write in an accompanying science: Insights According to biologists Gloria Muday and Heather Brown-Harding, researchers must conduct future experiments to prove that it is not glutamate that travels long distances around the plant, but rather the proposed calcium.
Quite unbelievable for a motionless organism without a central nervous system. Plants can not run away, nor bite teeth with teeth and claws, but they are not totally defenseless either.
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