Although a number of species in the truffle genus Tuber are harvested for human consumption, the Périgord Black Truffle (Tuber melanosporum) and the Piedmont white truffle (T. magnatum) dominate the truffle trade. Although it is now cultivated more widely (e.g., in Morocco, Australia, New Zealand, Canada, the United States, Argentina, Chile and Israel), T. melanosporum is native to calcareous soils in southern Europe, occurring in Spain, France, Italy, Greece, Bulgaria, Romania, and Turkey between 40° and 48° N (Jeandroz et al 2008). The Périgord Black Truffle is the underground fruiting body of T. melanosporum, an ascomycete fungus that forms ectomycorrhizal associations with the roots of various host plants (typically oaks [Quercus], hazels [Corylus], or other broad-leaved plants). Tuber melanosporum (and some of its relatives) apparently produce chemicals that inhibit plant growth in the soil around the truffle and its plant host. Streiblova et al. (2012) reviewed the current state of knowledge regarding the mechanisms behind this phenomenon.
Truffle prices range into the hundreds (or even thousands) of Euros per kilogram. The high demand for black truffles has led to intensive efforts at cultivation. The life cycle and ecology of this species is complex (Kües and Martin 2011 and references therein), but significant progress has been made in "truffle farming". Nevertheless, commercial production does not come close to meeting demand. Many growers hope that the recently released 125 megabase haploid genome sequence for this species will provide new opportunities to achieve a deeper understanding of the biology of this truffle that will in turn allow progress in developing commercially viable cultivation techniques.
The recent detection of the very similar Chinese Black Truffle (T. indicum) in an Italian truffle plantation has raised concerns about the potential impact of this exotic truffle on the native (and more commercially valuable) T. melanosporum (Murat et al. 2008).
(Martin et al. 2010; Kües and Martin 2011 and references therein)