For about half the global population, rice is the staple food. Yet every year, a fungal disease - rice blast - destroys harvests that could feed 60 million people. Researchers at the Karlsruhe Institute of Technology (KIT) have uncovered how the pathogen outsmarts the rice plant's defense system. The findings open up new possibilities for making rice more resilient, directly benefiting global food security.
The fungus causing rice blast disease is found in more than 85 countries worldwide, affecting not only rice but also other cereals. Infestation spreads rapidly: Within a few days, large areas of dead leaves appear and the crop's grain production nearly comes to a stop. In Asia and South America, rice blast is therefore as much of a threat to food security as mildew in cereals or potato blight, both known in Europe.
Kamikaze Attack on Cells: How the Fungus Outsmarts the Crop's Immune System
The KIT team investigated how the fungus outsmarts the crop's natural defenses. Plants do not produce antibodies as humans do, but they have indeed their own highly effective immune system. Its key component is a compound called salicylic acid - the natural precursor to aspirin. If one of the plant's cells is attacked, salicylic acid triggers an emergency response: The cell dies in a controlled manner, taking the pathogen with it, thus protecting the neighboring cells.
Defense Becomes a Deadly Trap
The rice blast fungus exploits this kamikaze mechanism. It produces a substance called pyriculol that is chemically similar to salicylic acid. "The fungus sends a false alarm signal to the plant," said Professor Peter Nick from KIT's Botanical Institute. "The plant shows a panic reaction, disables important defense mechanisms and activates its self-destructive cell death even before the fungus actually invades the plant." You can imagine the process like this: "The fungus gives the plant a kind of fake aspirin, which triggers the cells' self-destructive defense mechanism, but without the protective effect it normally has."
Every year, the rice blast disease destroys enormous
amounts of crops in Asia and South America.
(Photo: Karlheinz Knoch, KIT)
The Fungus Benefits in Two Ways
The rice blast fungus benefits in two ways from the premature self-destruction of the plant cells: It uses the dead tissue as a source of energy. At the same time, the false alarm signal suppresses precisely those mechanisms that would normally make cell death an effective protective response. Nutrients are freely available to the parasite - while the plant's immune response is blocked.
"Cooler" Rice Varieties in the Future Avoid Disastrous Panic Reactions
The researchers have made another discovery: "There are rice varieties that react less strongly to the attack - they are, so to speak, able to stay cool," said Peter Nick. These plants are resistant and can keep the parasitic pest in check. "This means that we could protect the crop against the Kamikaze mechanism by neutralizing the panic signal." Nick suggests focusing on the cultivation of varieties with this specific trait and growing them on a larger scale.
Impact on Food Security
The study provides an important basis for a more targeted fight against rice blast - not only by using fungicides, but also through a deeper understanding of the crop's defense mechanisms. This benefits above all regions where rice is essential for the population's survival.
Original publication
Junning Ma, Jean-Benoît Morel, Michael Riemann, Stefan Jacob, Peter Nick, Pyriculol effects on plant defence in rice: a virulence-independent secondary metabolite enhances host immunity against Magnaporthe oryzae, Journal of Experimental Botany, Volume 77, Issue 8, 15 April 2026, Pages 2594-2610, https://doi.org/10.1093/jxb/erag061
