Impact of the competition between mating types on the cultivation of Tuber melanosporum: Romeo and Juliet and the matter of space and time

Major breakthroughs in our understanding of the life cycles of the symbiotic ascomycetes belonging to the genus Tuber have occurred over the last several years. A number of Tuber species produce edible fruiting bodies, known as truffles, that are marketed worldwide. A better understanding of the basic biological characteristics of Tuber spp. is likely to have tremendous practical relevance for their cultivation. Tuber melanosporum produces the most valuable black truffles and its genome has been recently sequenced. This species is now serving as a model for studying the biology of truffles. Here, we review recent progress in the understanding of sexual reproduction modalities in T. melanosporum. The practical relevance of these findings is outlined. In particular, the discoveries that T. melanosporum is heterothallic and that strains of different mating types compete to persist on the roots of host plants suggest that the spatial and temporal distributional patterns of strains of different mating types are key determinants of truffle fructification. The spatial segregation of the two mating types in areas where T. melanosporum occurs likely limits truffle production. Thus, host plant inoculation techniques and agronomic practices that might be pursued to manage T. melanosporum orchards with a balanced presence of the two mating partners are described.