(ORDO NEWS) — Japanese researchers have uncovered the secret behind the rapid movements of Mimosa pudica leaves in response to touch and injury.
It turned out that calcium ions (Ca2+) play the most important role in this process, and the mechanism itself protects the plant from insect attacks.
Unlike animals, plants do not have the nerves and muscles that would allow them to move quickly. However, Mimosa pudica, known as the bashful mimosa, can move its leaves instantly in response to touch or injury.
Until now, both the signaling molecules that trigger this movement and the physiological role of this process have remained mysteries. Now researchers from Saitama University (Japan) have been able to answer these questions.
Shy mimosa is the most famous non-insectivorous plant that can move quickly. Previous research has shown that electrical signals action potentials, short-term changes in membrane potential that are also the basis of nerve impulses, are critical to mimosa’s rapid movements.
The authors of the new article have created fluorescent plants that allow real-time recording of the intracellular concentration of calcium ions (Ca 2+ ) and action potentials.
It turned out that when the sheet was damaged, the action potential and the change in Ca 2+ concentration propagated at the same speed and passed through the recording site at the same time.
Treatment of Mimosa pudica leaves with Ca 2+ channel inhibitors and Ca 2+ trap reagents blocked both action potentials and leaf movements in response to touch.
These data supported the idea that Ca 2+ acts as a signaling molecule that triggers rapid leaf movement.
To determine the role of leaf movements, the scientists created a transgenic immobile Mimosa pudica and compared it to wild-type plants.
It turned out that herbivorous insects, such as grasshoppers, ate more immobile leaves than ordinary ones.
The researchers also visualized Ca 2+ signals, leaf movements, and grasshopper behavior on the leaf under a microscope.
When the insect was feeding, the leaflets began to fold sequentially along with the propagation of Ca 2+ signals, preventing the grasshopper from continuing to feed.
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