Truffle trouble: what happened to the Tuberales?

Area of Science:

• Mycology
• Evolutionary Biology
• Molecular Systematics

Background:

• Truffles, historically classified in Tuberales, are now recognized within the Pezizales.
• Morphological and biological traits define truffle characteristics.
• Previous classifications relied heavily on traditional morphological features.

Purpose of the Study:

• To provide an overview of truffles within the Pezizales.
• To analyze the phylogenetic relationships of hypogeous (underground) and epigeous (aboveground) Pezizales taxa.
• To re-evaluate truffle classification based on molecular data and morphology.

Main Methods:

• Phylogenetic analyses using Large-subunit ribosomal DNA (LSU rDNA) sequences.
• Inclusion of 55 hypogeous and 139 epigeous taxa from the Pezizales.
• Application of Parsimony, Maximum Likelihood (ML), and Bayesian inference methods.

Main Results:

• Phylogenetic analyses revealed at least 15 independent evolutionary lineages of truffles within the Pezizales.
• Hypogeous truffle forms were found nested within various major evolutionary lines, often near epigeous (apothecial) relatives.
• Traditional defining characters, such as amyloid reactions in ascus walls and the number of nuclei in ascospores, were found to be more variable than previously assumed.

Conclusions:

• The study supports the reclassification of truffles within the Pezizales, highlighting their polyphyletic origins.
• Molecular data combined with morphology provide a robust framework for understanding truffle evolution and classification.
• Re-evaluation of traditional taxonomic characters is necessary for accurate truffle systematics.