Julie Ducla has investigated how plants respond when the roots of neighbouring plants are damaged. Photo: Anne Honsel
Below ground, plant roots grow alongside those of neighbouring plants, but little is known about how they respond when a neighbouring root is damaged. In her doctoral thesis, Julie Ducla shows that healthy plants can detect this damage and redirect their root growth away from it.
When Julie Ducla started her PhD, she set out to answer three questions: Can a plant detect damage to the root of a neighbouring plant? If so, what signal passes between them? And how does the healthy plant respond?
Scientists already knew that damaged or infected leaves can release airborne signals that affect neighbouring plants. Much less was known about whether roots can perceive signals from damaged roots of neighbouring plants.
“If we know someone has the flu, we might keep our distance to avoid becoming infected,” says Julie Ducla. “Plants cannot move from one place to another, and they do not talk to each other like we do. We wanted to know whether roots can sense damage to the roots of neighbouring plants, and how they respond.”
Roots respond within a second
Julie Ducla worked with seedlings of the small model plant Arabidopsis and placed them next to each other. Using two-photon microscopy, she damaged a single cell in one root with a laser and watched what happened in the root of the neighbouring seedling.
“We looked for calcium signals, which plant cells use to rapidly pass on information about stress,” explains Julie Ducla. “Within one second of damaging the cell, we saw a calcium signal in the neighbouring healthy root. The speed really surprised me.”
The next challenge was to identify the signalling molecule. The researchers suspected protons – positively charged particles that make the surroundings more acidic when their concentration increases.
An Arabidopsis root next to the organic electronic ion pump used to deliver protons without creating a flow of liquid. Photo: Julie Ducla
To test the hypothesis, Julie Ducla collaborated with researchers specialising in organic electronics. They used an organic electronic ion pump that could deliver protons next to the root without creating a flow of liquid, allowing them to test the effect of the protons alone.
“It was a difficult setup because we needed to place the pump next to the root of a seedling without touching it,” says Julie Ducla. “When the pump triggered the same response as the wounded root, we knew that protons were the signal.”
A similar calcium response occurred when an Arabidopsis root was placed next to a wounded tomato root, suggesting that this type of signalling may also occur between different species.
The effects went beyond this rapid calcium signalling. The researchers also found changes in the activity of stress- and defence-related genes as well as in root growth.
“What surprised me most was seeing the roots grow away,” says Julie Ducla. “We had identified the signal, but then we saw that the healthy root actually changed its growth direction.”
The response also occurs in soil
Most of these experiments were carried out in a transparent gel-like growth medium, where the tiny roots could easily be observed under a microscope. But roots do not normally grow in transparent gel. They grow in soil, where microscopy becomes much more difficult.
Soil blocks light, and some of its components naturally glow when illuminated under the microscope, making imaging much more difficult.
“It is very, very tricky to image anything in soil,” explains Julie Ducla. “We had to develop a new method, and we could show that even in soil, a healthy root responds when a neighbouring root is wounded.”
For Julie Ducla, the work also points to a broader way of looking at plant stress.
“We tend to focus on the stressed plant itself, but it is also important to look at what is happening around it and how neighbouring plants affect each other,” says Julie Ducla.
About the public defence
Julie Ducla, Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, defended her doctoral thesis on 25 August 2026. The faculty opponent was Christian Hardtke, University of Lausanne, Switzerland. The thesis was supervised by Peter Marhavý and Stéphanie Robert. The research was carried out in collaboration with several researchers and research groups, including the Electronic Plants group led by Eleni Stavrinidou at Linköping University, Theresia Arbring Sjöström at Linköping University and Joris Sprakel’s group at Wageningen University.
Title of the thesis: Below Ground Damage Perception in Plants
Link to the PhD thesis: https://doi.org/10.54612/a.1so6l4htb6
For questions, please contact:
Julie Ducla
Umeå Plant Science Centre
Department of Forest Genetics and Plant Physiology
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