Injured plants sound the alarm with a pressure wave
Roots respond to predators with a newly discovered, physically mediated defence mechanism. It works thousands of times faster than known chemical signals.
Inside a root, there is high pressure – until something bites into it. The sudden drop in pressure helps neighboring root parts prepare for the attacker. This physically mediated defense reacts much faster than chemical signals, as are known from other plant organs. A research team led by biologist Angel Baudon from the University of Würzburg has discovered the mechanism in experiments.
Since plants cannot run away, they defend themselves with defensive substances. If, for example, a caterpillar eats a leaf, released chemical substances and electrical signals trigger an immune response. However, experts knew comparatively little about how this works in the underground parts of plants.
The team led by Baudon investigated the popular model organism Arabidopsis thaliana, or thale cress. They specifically injured individual roots and measured how the signaling substance calcium spread in surrounding lateral roots, as well as the electrical impulses in neighboring root parts.
To their surprise, the experts found that in all cases of injury, the neighboring roots reacted practically immediately, within milliseconds. Apparently, a signal propagated through the root system at several centimeters per second. As they write in their publication, this is about 10,000 times faster than the calcium waves known from similar scenarios in above-ground plant parts.
Instead, the decisive informant in the soil appears to be hydrostatic pressure: the cell wall and cell water press strongly against each other, and any injury causes this equilibrium to collapse and a pressure wave to form. It travels extremely quickly through the root system. According to the study, so-called mechanosensitive channels then convert the physical stimulus into electrical impulses in distant areas. These ultimately trigger an immune response.
Apparently, special rules with different sensors and mechanisms than previously known apply to underground pest defense. However, how these laboratory results from the model organism can be transferred to crops still needs to be researched.
Spektrum der Wissenschaft
We are partners of Spektrum der Wissenschaft and would like to make well-founded information more accessible to you. Follow Spektrum der Wissenschaft if you like the articles.
Experts from science and research report on the latest findings in their fields – competent, authentic and comprehensible.
From the latest iPhone to the return of 80s fashion. The editorial team will help you make sense of it all.
Show all
