Morphological characterization of molecular-typed Tuber magnatum ectomycorrhizae

Abstract.

Recent reports of discrepancies between the morphological and molecular-based characterization of Tuber magnatum ectomycorrhizae suggest misleading morphological typing of these structures. This study reports a new morphological and anatomical description of T. magnatum ectomycorrhizae at different development stages using nursery-inoculated host plants. Both ascocarps, used as spore donors in the inoculation process, and the resulting ectomycorrhizae were first checked by single-step PCR analysis using a T. magnatum species-specific ITS primer pair. Direct sequence analysis of the entire ITS1–5.8S-ITS2 fragment of DNA from mycorrhizal pools demonstrated the purity of the samples processed. Thus, the validity of the criteria reported here for the morphological identification of T. magnatum symbiotic structures is supported by molecular analysis. When diagnostic morphological traits appear only occasionally, as a result of ageing or of particular edaphic conditions, only molecular markers such as the species-specific ITS primers designed here ensure reliable typing of T. magnatum mycorrhizae for the purpose of controlling and/or certifying mycorrhizal plants present on the market.