A xylan hydrolase contributes to pathogenicity and induces resistance to pathogens in a schizotrophic fungus

Abstract BACKGROUND Xylanases are widely distributed in fungi, and are involved in the breakdown of carbohydrates and polysaccharides in plant cell walls, and activating host immune responses. However, the role of xylanase in regulating the interaction between schizotrophic fungi and both the symptomatic host plant and the endophytic host is not yet clear. RESULTS A secretory xylanase, SsXyl3, was identified from the schizotrophic fungus Sclerotinia sclerotiorum , which contains a glycoside hydrolase family 11 domain and a signal peptide. SsXyl3 is associated with vegetative growth and sclerotial development and influences sugar metabolism in S. sclerotiorum, as demonstrated by phenotyping SsXyl3 mutants and RNA‐seq analysis. Additionally, SsXyl3 is crucial for the complete virulence of S. sclerotiorum , and is further involved in establishing the symbiotic relationship between S. sclerotiorum and wheat plants. It also regulates the induction of resistance against stripe rust and Fusarium head blight (FHB) diseases in wheat by S. sclerotiorum . CONCLUSION These results highlight that S. sclerotiorum induces resistance to stripe rust and FHB diseases in wheat, and shows complete virulence in symptomatic hosts through secreting SsXyl3. These findings offer valuable clues for developing innovative and eco‐friendly crop disease control methods for FHB and stripe rust diseases in asymptomatic wheat and Sclerotinia diseases in symptomatic hosts. © 2025 Society of Chemical Industry.