Even for plants, there can be too much of a good thing. When nitrogen levels are too high, for example due to excessive fertilization, plants become more susceptible to certain diseases. However, the exact reasons are not yet fully understood.
A group of researchers involving the Technical University of Munich (TUM) has now taken the first steps towards answering this question. They identified a small protein (peptide) that makes the plant resistant to certain bacteria. However, its effect is limited when there is a high nitrogen supply. The research is published in the journal Nature Communications.
“The immune system of plants and humans is much more alike than one might initially think. In plants, hormone-like peptides are involved in the immune response, and there, too, is a complex interplay between nutrition and health,” explains Ralph Hückelhoven, Professor of Phytopathology at TUM.
Together with other researchers, a working group at his chair, led by Martin Stegmann, identified one of the connecting points of this relationship: the C-terminally encoded peptides (CEPs). These are plant peptide hormones, known as phytocytokines, which serve various functions as messenger substances, from stress response to root formation. The study now shows that they also play a role in the plant´s immune defense.
The researchers demonstrated that plants were more susceptible to bacterial infections if they produced less of these peptide hormones or if their sensors on the cell surface were missing. It was also shown that plants produced more peptide hormones as they were attacked by bacteria.
For this purpose, the researchers exposed the test plants to pathogenic bacteria of the genus Pseudomonas. This shows that the peptide hormones are closely linked to the plant’s resistance to bacterial pathogens.
Antibacterial resistance is nitrogen-dependent
Nitrogen is an important fertilizer. However, high nitrogen concentrations affect the signaling pathway of the investigated peptide hormones. The research showed that the resistance to bacteria mediated by the peptide hormones was reduced when the plants were exposed to high nitrogen concentrations, making the plants more susceptible to diseases.
“These results provide starting points for further research into the reason and mechanisms behind this link between the plant’s nutritional status and immune defense,” explains Hückelhoven.
The research may also have implications for agricultural practice. Here, higher susceptibility to certain diseases due to excess nitrogen levels may limit crop health. Hückelhoven explains, “With our newly gained knowledge, it might be possible in the future to breed crops that are particularly resistant to disease, even with a moderate application of nitrogen.”
More information:
Jakub Rzemieniewski et al, CEP signaling coordinates plant immunity with nitrogen status, Nature Communications (2024). DOI: 10.1038/s41467-024-55194-x
Provided by
Technical University Munich
Citation:
Too much of a good thing: How high nitrogen levels compromise plant immunity (2025, February 27)
