When a Plant Gets Hurt, An Amazing Reaction Happens
At the point when plants are under attack – say, for example, by a creepy crawly making a leaf dinner – their defense system are raised in different parts. How would they know to do that?
The defense System is More Similar to Animals
As indicated by new research, plants utilize similar signaling molecules that animals use in their nervous system. Our green companions don’t have nerves, precisely – yet they absolutely have something surprisingly comparable.
The research involved using fluorescent proteins to mark and watch the signals as they travel in waves through plants in response to a stressor.
“We know there’s this systemic signaling system, and if you wound in one place the rest of the plant triggers its defense responses. But we didn’t know what was behind this system,” explained botanist Simon Gilroy from the University of Wisconsin-Madison.
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How does Plant Defense System work when it gets hurt?
If a plant gets wounded, an electrical charge fire, propagating across the plant. The unknown part was what triggered that charge and helped propagate it – but that’s not even what the researchers were trying to study.
What they were originally looking at was how plants respond to gravity by studying increases in calcium. So botanist Masatsugu Toyota genetically engineered a mustard plant that would let the researchers observed changes in calcium concentration in real-time.
He introduced a protein that only fluoresces in the presence of calcium. And then the researchers cut a leaf to see if they could detect calcium changes.
The Process in Animals
In animals, an excited nerve cell releases an amino acid called glutamate, which triggers a wave of electrically charged calcium ions that propagate to cells farther and farther away from the site.
As should be obvious from the video, the end result for the plants is absolutely extraordinary. Waves of light stream out from the source of the injury, spreading through the plant at the speed of about a millimeter for each second.
It’s a lot slower than animal nerve signals, which can travel up to 120 metres per second (268 mph), but for plants this is super speedy communication.
How does Plant protect itself in case of an Injury?
The researchers discovered that once the wave hits, defensive hormones rise in that region of the plant.
This tells the plant to mount its defenses, such as an increase in noxious chemicals that will make the plant unpalatable to munching insects, or – as is known in the case of grass – the release of smelly volatiles that signal parasitic wasps to come and lay their eggs in insects that might be eating it.
Video: UW-Madison Campus Connection
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Difference between Plant’s Defense System and Animals Defense System
Apart from the speed of reaction or response which is much greater in animals, what was triggering the researchers was the calcium waves? Just like in animals, the researchers believed it might be glutamate, which is also found in plants. And previous research published in 2013 revealed that plants missing glutamate receptors also did not have an electrical threat response.
So the research team wounded plants without glutamate receptors to see if there was an effect on calcium flow.
“Lo and behold, the mutants that knock out the electrical signaling completely knock out the calcium signaling as well,” Gilroy said.
This research puts together various pieces to solve the puzzle of how plants cells communicate. The wound spills glutamate, which is taken up by receptors that trigger calcium ion propagation, which in turn switches on the plant’s defense system to try and protect against further damage.
And they do it all without actual nerves. Pretty cool, huh? Looks like our green brethren are a lot more complex and dynamic than they seem and we need to explore a lot out there.
The team’s research has been published in the journal Science.
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