Secondary metabolites and their impact on symbiotic interactions in the ambrosia fungus Geosmithia eupagioceri

Ambrosia fungi colonize dead trees, providing nutrition for ambrosia beetles. A key aspect of this symbiosis is the ability of fungi to colonize and dominate the wood around the beetle tunnels. Hypotheses for these dynamics include active beetle management, fungal inoculation priority, and the chemical ecology of the fungus. The ecological role of allelochemicals produced by ambrosia fungi is unknown. This study presents an analysis of secondary metabolites from Geosmithia eupagioceri (Ascomycota: Hypocreales). Eight extracellular compounds were identified: 5-hydroxymethyl-2-furancarboxylic acid, several hydroxybenzoic acid derivatives, 4-hydroxyphenylacetic acid (4-HPA), 4-HPA methyl ester, tyrosol, and thymine. Most compounds show cross-taxon activity, suppressing the growth of bacteria, fungi, a nematode, and a mite. We also point out that these compounds also have potential to modulate the physiology of their producer, the beetle host and associated microbes through synergism.