Phylogeny and ecological roles shaping yeast-hyphae morphogenesis in Ophiostomataceae

Area of Science:

• Mycology
• Evolutionary Biology
• Fungal Genetics

Background:

• The Ophiostomataceae family includes diverse fungi exhibiting yeast-hyphae dimorphism.
• This dimorphism is crucial for pathogenic (e.g., Dutch elm disease) and symbiotic (e.g., ambrosia fungi) lifestyles.
• Understanding dimorphism's role is key to fungal adaptability and ecological function.

Purpose of the Study:

• To investigate the interplay between dimorphism and fungal lifestyles across Ophiostomataceae genera.
• To determine the evolutionary origins and patterns of dimorphism within the family.
• To explore the correlation between dimorphism and the ambrosia lifestyle.

Main Methods:

• Cultured six Ophiostomataceae genera (Raffaelea, Harringtonia, Leptographium, Ophiostoma, Heinzbutinia, Esteya) representing four lifestyles.
• Assessed yeast morphotype growth under standardized conditions with DL-proline as the sole nitrogen source.
• Analyzed the evolutionary history and phylogenetic signal of dimorphism.

Main Results:

• All tested strains, except one, showed increased yeast morphotype growth (≥50%).
• Species exhibited varied responses to inoculum size, indicating inter-species variation.
• Dimorphism likely evolved in the common ancestor and shows a strong phylogenetic signal, with conserved presence or loss within lineages.

Conclusions:

• Dimorphism is an ancestral trait in Ophiostomataceae, conserved within lineages.
• Dimorphism and the ambrosia lifestyle are evolutionarily correlated within this family.
• This interplay significantly shaped the evolutionary trajectory of Ophiostomataceae.