This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Plants cannot run away when the wind picks up, rain lashes down or a hungry herbivore begins chewing on their leaves. Instead, they must sense their surroundings and adapt.
Now, researchers have uncovered an important piece of the puzzle of what happens inside plants when they are exposed to touch, injury or other physical stimuli. By subjecting the plant Arabidopsis thaliana (thale cress), a small flowering weed related to mustard and cabbage, to different forms of mechanical stimulation, the research team showed that a chain of three specific proteins becomes activated. These proteins, known as MAP kinases, are activated within a minute and then send signals that affect the activity of hundreds of genes and contribute to changes in plant growth.
"We have known for more than 25 years that mechanical stimulation activates MAP kinases, but a crucial piece of the puzzle has been missing: what triggers the signal and how it is linked to the plant's subsequent development. We have now identified that signaling pathway," says Olivier Van Aken, a biology researcher at Lund University. The work is published in the journal Nature Communications.
The researchers combined genetic, molecular and large-scale analyses of gene activity and proteins to track what happens inside the plant following mechanical stimulation. The study shows that the protein groups MAPKKK3/4/5, MKK4/5 and MPK3/6 form a central signaling pathway. Activated quickly after mechanical stimulation, the pathway functions like a protein-based cascade, controlling a large part of the plant's early response to touch.
The study also shows that the signaling pathway influences how plants grow when exposed to repeated mechanical stress. This phenomenon, known as thigmomorphogenesis, means that recurring wind exposure or attacks from herbivores and insects can alter a plant's growth, shape and defense. "It is remarkable that a signal initiated within a minute can have such widespread effects," says Huy Cuong Tran, a biology researcher at Lund University and first author of the study.
The findings provide new insight into how plants perceive and adapt to their physical environment. In the longer term, the research may contribute to a better understanding of how plants cope with mechanical stress and how environmental conditions influence growth and resilience. However, this remains fundamental research.
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