Whose truffle is this? Distribution patterns of ectomycorrhizal fungal diversity in Tuber melanosporum brûlés developed in multi-host Mediterranean plant…

Elisa Taschen, Mathieu Sauve, Adrien Taudiere, Javier Parlade, Marc-André Selosse, Franck Richard

In the Mediterranean region, patches of vegetation recovering from disturbance and transiently dominated by shrubs produce one of the world's most prized fungi, the black truffle (Tuber melanosporum). In these successional plant communities, we have fragmentary knowledge of the distribution of T. melanosporum in space among ectomycorrhizal (ECM) host species and in time. Molecular identification of hosts (RFLP) and fungi (ITS sequencing) and quantification of T. melanosporum mycelium (qPCR) were employed to evaluate the presence of T. melanosporum on four dominant ECM host species (Quercus ilex, Q. coccifera, Arbutus unedo, Cistus albidus) and the extent to which their respective ECM communities shared fungal diversity, over the course of development of truffle grounds, from recent unproductive brûlés to senescent ones where production has stopped. We found that truffle grounds host rich communities in which multi-host fungal species dominate in frequency. When considering both ECM tips and soil mycelia, we documented a dynamic and spatially heterogeneous pattern of T. melanosporum distribution in soils and a presence of ECM tips restricted to Q. ilex roots. This study advances our knowledge of the ecology of T. melanosporum, and provides insight into the extent of ECM fungal sharing among plant species that dominate Mediterranean landscapes.