The international team of scientists found out during the experiment that the plants use signaling molecules similar to those found in the nervous system of animals. With the help of these molecules, plant leaves can transmit to each other “distress signals” containing information about the hazard. Our green friends do not have a nervous system, but they definitely have something similar. Conclusions of the researchers published the journal Science.
In animals, irritated cells of the nervous system release glutamic acid, which creates an electrochemical release of calcium ions, through which the cell moves away from the dangerous area. In this process, neurotransmitters are involved – substances through which the impulse is transferred from one neuron to another. Researchers from the United States and Japan found that plants have a very similar system.
Interestingly, the authors of the study came to this discovery accidentally when they studied the effect of gravity on the change in calcium levels in a herbaceous Arabidopsis plant. One of the scientists created a molecular sensor – a fluorescent substance that is sensitive to the content of calcium and allows you to observe changes in its level in the plant in real time. The higher the level of calcium, the brighter it glows. Using a molecular sensor, scientists were able to see how the level of calcium in the plant tissues varies under different conditions.
“We knew that plants have a signal system. If you damage one part, it notifies everyone else that they have triggered protective mechanisms. But we did not know what was behind this system, “explains Simon Gilroy, a biologist at the University of Wisconsin in Madison.
If one leaf of a plant is torn off or damaged, the stalk and other leaves quickly recognize it. In the course of the experiment, scientists cut off one leaf from the rezuchovidka and found that the calcium content began to change immediately – a kind of impulse was generated that spread from the damaged part throughout the plant. The glow of the fluorescent sensor sharply became brighter near the “wound”, then faded and appeared a little further. After a while, this wave reached all the other leaves.
In the video below you can see how the illuminated signal is transmitted from the damaged part of the plant. The ejection velocity is only about a millimeter per second, which is much slower than in animal nerve cells (120 meters per second). Nevertheless, it is quite enough for the rest of the plant to start the process of producing protective mechanisms. For example, some plants begin to produce more chemically harmful substances, becoming inedible for insects, others scare off their offenders with a sharp smell.
The reaction of a plant to its eating by a caterpillar
What exactly increases the level of calcium in a plant? The authors of the study believe that the whole thing is in the same glutamic amino acid (glutamate), which was also previously found in plants. This is also indirectly evidenced by the findings of another study, conducted in 2013. They said that plants that do not have glutamate receptors do not have an electrical reaction to the threat.
Glutamate triggers the reaction
The resulting wound results in the release of glutamate. It is taken by receptors that increase the level of calcium, which in turn leads to the launch of a protective system, which in turn tries to protect the plant from further damage. And all this happens without neurons. It seems that our green friends are much more complex and dynamic than they may seem at first glance.
Scientists add that they will continue to study the signal system in plants more and will probably find a way to manage it.
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