"Plants don’t get a fever - they boost their defence mechanisms"

A research team led by Prof Gundula Noll (University of Münster) and Dr Alexandra Furch (University of Jena) has deciphered how plants use electrical signals to defend themselves against pathogens. In an interview with Christina Hoppenbrock, Gundula Noll shares insights into the immune response of plants and her latest research findings.

 

Is the plant immune response comparable to that of animals and humans?

No. Plants have their own way of defending themselves. While animals have specialised immune cells that specifically seek out and eliminate pathogens, plants go about this differently. They do not have a circulating immune system that wanders through the body but react locally and systemically with a sophisticated signalling system. When an attacker is detected, affected cells send out chemical and electrical alarm signals that activate defence mechanisms – their own biological early warning system, so to speak. These signals spread via the vascular tissue, especially via the phloem, which is actually responsible for transporting nutrients. So plants don’t get a fever - instead they boost their defence mode.

How well researched is the immune system of plants?

There are still plenty of exciting mysteries. It is particularly fascinating that plants do not work with just one type of signal, but rather a combination of electrical and chemical signals. It is not yet clear which of these signals set the tone. The current focus is on peptides and hormones, but the final proof is still missing. And then there is the question of how exactly these signals are processed. Electrical plant signals sweep through the plant via the phloem - but what happens next? Which cells 'understand' them and how do they finally trigger a defence response?

Why is it important to know how plants respond to pathogens?

It is the key to sustainable crop protection. The better we understand how plants activate their natural defences, the more targeted we can support them – without the massive use of chemicals. This will not only help the environment, but also agriculture by enabling robust crop varieties that can defend themselves against new pathogens. Especially in times of climate change, as new pathogens suddenly emerge, we need plants that are resilient.

Your current work shows that harmful bacteria trigger electrical impulses and other reactions in the plant. How does this work?

You can imagine it as a kind of plant nervous system – only without a brain. As soon as the plant senses a bacterial signal, certain ion channels in the cell membranes are activated and set off a chain reaction. Charged particles flow through the cells and generate an electrical wave that spreads across the phloem. This is similar to the way nerve cells work – not quite as fast, but extremely effective. These electrical signals trigger a whole cascade of defence reactions. They trigger chemical signals such as calcium ions and reactive oxygen compounds, which initiate the actual counterattack against the pathogen.

Were you surprised by your results?

Definitely. It was particularly exciting to find this mechanism in two very different plant species – thale cress and fava bean. This shows that this strategy is evolutionarily proven and probably plays a role in many plants. Another highlight was the discovery of an unexpected role for special phloem barrier proteins (SEOR proteins). It was previously thought that they were only responsible for regulating the flow of nutrients. But no: they also have a function in the immune response. This opens new doors for research – could these proteins be specifically manipulated to make plants more resistant? There are numerous possibilities.

 

 

Original publication:

Furch A. C. U. et al. (2025): Transformation of flg22 perception into electrical signals decoded in vasculature leads to sieve tube blockage and pathogen resistance. Sci. Adv. Vol 11, Issue 9; DOI:10.1126/sciadv.ads6417

Further information

• Original publication in "Science Advances"
• The research group "Plant Biotechnology" at the Institute of Plant Biology and Biotechnology
• The research group "Vascular Biology" at the Matthias Schleiden Institute of the University of Jena
• Gundula Noll/Fraunhofer Institute for Molecular Biology and Applied Ecology IME