Plants in the crossfire: Nitrogen increases susceptibility to disease!

Plants in the crossfire: Nitrogen increases susceptibility to disease!

In modern agriculture, fertilizer use is often discussed, particularly the effects of excessive nitrogen use. Researchers of the Technical University of Munich (TUM) have found that high nitrogen levels in plants not only affect their growth, but also their health. A key finding of their studies shows that increased nitrogen supply makes plants more susceptible to certain diseases.

The TUM researchers have identified a small protein known as C-terminally encoded peptides (CEPs), which plays a crucial role in plant immune defense. Ralph Hückelhoven, professor of phytopathology, explains that high nitrogen content limits the plants' immune defenses. Crucially, when nitrogen concentrations are high, plants produce fewer CEPs or even lose sensors for these hormones, making them more susceptible to bacterial infections.

The role of C-terminally encoded peptides

CEPs are plant peptide hormones that act as messengers and help regulate immune responses. The studies show that plants produce more peptide hormones when attacked by bacteria. The researchers placed test plants with pathogenic bacteria of the genusPseudomonasand observed that high nitrogen concentrations negatively influence the signaling pathway of the CEPs. These results suggest that moderate nitrogen application in agriculture could help produce more disease-resistant crops.

Furthermore, the findings demonstrate that the use of receptor kinases (RKs) in plants plays a central role in the control of growth, development and immunity. RKs act as pattern recognition receptors that can detect microbe-associated molecular patterns and thus activate pattern-activated immunity (PTI), as observed for example in Arabidopsis thaliana.

Nutrient supply and immunity in interaction

Additionally, research shows that reduced nitrogen availability improves the activation of certain immune pathways and thus increases bacterial resistance. Research has confirmed that the expression of CEP4, a specific CEP, is downregulated by bacterial flagellin treatment, indicating a complex regulatory mechanism linking nutrient synchronization and immunity.

These connections between fertilization and plant health not only shed light on the mechanisms of disease resilience, but also expand our understanding of plant immune responses. CEPs play a key role in the signaling pathways that control the response of plants to nutrient availability and pathogenic stimuli. In the future, this knowledge could be crucial for developing sustainable farming methods that both increase yields and minimize plants' susceptibility to disease.