Lysine crotonylation enhances fungal effector activity and promotes invasion of host plants.

Phytopathogenic fungi secrete a large arsenal of effectors to facilitate host infection; however, the mechanisms regulating the activity of these virulence proteins remain elusive. Here, we show that at least 86 putative effectors in the fungal pathogen Fusariumoxysporum f. sp. lycopersici are crotonylated within their enzymatic domains, as revealed by proteomic analysis. Crotonylation of a chitinase and two plant cell wall-degrading enzymes by the fungus-specific crotonyltransferase FolRtt109 enhances their enzymatic activities and consequently promotes fungal invasion. Conversely, application of an Rtt109 inhibitor attenuates effector activity, leading to reduced fungal virulence. Notably, this inhibitor exhibits broad-spectrum efficiency against multiple phytopathogenic fungi without detectable adverse effects on host plant seedlings. Collectively, these findings demonstrate that crotonylation regulates effector activity in plant fungal pathogens to influence virulence and highlight the potential of targeting this modification as a fungicide strategy for plant disease control.