The Ash Dieback Pathogen Resists the Chemical Defences of Its Host Tree, European Ash, by Depleting Them From the Growth Medium.

Hymenoscyphus fraxineus resists European ash defenses by depleting host compounds, with 48% of detected chemicals significantly reduced after fungal growth.

• Why it matters: Understanding how the ash dieback pathogen overcomes host defenses is crucial for managing its spread and ecological impact, as it causes widespread decline of Fraxinus excelsior in Europe.
• What they did: The study examined H. fraxineus responses to ash leaf extracts and defense compounds, finding it is not inhibited by them and can deplete these compounds extensively from the growth medium, with 48% of chemical features reduced.
• The result: H. fraxineus growth is promoted by ash metabolites, suggesting it uses host defensive compounds as carbon sources, which may facilitate successful colonization of ash tissues.