Researchers Identify Fungal Protein That Disarms Plant Defenses

Scientists from the United States Department of Agriculture (USDA) have identified a protein secreted by the fungus Fusarium graminearum that can suppress the natural defense mechanisms of host plants. The finding, published on the scientific platform bioRxiv, highlights the critical role of a protein named FgCYP_NO in the infection process of this pathogen, which causes Fusarium head blight (FHB) — one of the most damaging diseases in cereal crops like wheat, barley, and corn.

The study shows that FgCYP_NO functions as an effector — a type of protein released by pathogens to manipulate the host’s immune response. Specifically, it interferes with nitric oxide (NO) signaling, a key molecule in plant defense pathways. By suppressing NO production, FgCYP_NO allows the fungus to more easily colonize plant tissues.

“Inhibiting nitric oxide signaling is a powerful strategy for the pathogen to avoid detection and suppression by the plant,” the authors explain. Experiments revealed that plants with reduced NO levels were significantly more susceptible to Fusarium infection.

Fusarium head blight not only causes considerable yield losses but also compromises grain quality. In addition, F. graminearum produces harmful mycotoxins, such as deoxynivalenol (DON), which pose health risks to both humans and animals. The discovery of this effector protein provides valuable insight into how the fungus bypasses plant immunity and offers new leads for controlling the disease.

According to the researchers, identifying FgCYP_NO is a major step toward understanding how Fusarium graminearum overcomes the plant's natural defenses. “This protein is a promising target for developing future biotechnological and chemical control strategies,” they conclude.