Genetic and phylogeographic structures of the symbiotic fungus Tuber magnatum.

The quality and market price of truffles vary with the species and, traditionally, the place of origin. The premium species Tuber magnatum produces white truffles and has a patchy distribution restricted to Italy and some Balkan areas. We used polymorphic microsatellites to evaluate 316 specimens grouped into 26 populations sampled across the species' geographic range to determine if natural populations of T. magnatum are genetically differentiated. We found that the southernmost and the northwesternmost populations were significantly differentiated from the rest of the populations. The simple sequence repeat data also could be used to make inferences about the postglacial T. magnatum expansion pattern. This study is the first to identify a genetic and phylogeographic structure in T. magnatum. The presence of a genetic structure can be of practical interest in tracing truffle populations according to their geographic origin for marketing strategies. Evidence for extensive outcrossing in field populations of T. magnatum also is provided for the first time.