Symbiotic interactions between orchids and Tuber borchii

Tuber borchii is a precious truffle, which forms ectomycorrhizal associations with several coniferous and broadleaf trees, arbutoid mycorrhizas with the strawberry tree and recently it was found also to form orchid mycorrhizas with Epipactis atrorubens. In this work, we investigated the formation of T. borchii mycorrhizas in other orchid species (Anacamptis morio, Cephalanthera longifolia, Limodorum abortivum, Ophrys sphegodes, Orchis purpurea). To this aim the orchids growing in three T. borchii production areas located in Emilia Romagna region (Italy) were collected and the presence of T. borchii mycorrhizas was investigated by morphological and molecular approaches. For T. borchii molecular identification, specific primers were used by a nested PCR approach. Tuber borchii was identified in 2 out of 6 samples of A. morio, 3 out of 4 samples of C. longifolia, and 2 out 6 samples of O. sphegodes. The ecological and biological roles of the orchid association in the truffle life cycle are discussed.