Tuber Melanosporum

The Perigord truffle (Tuber melanosporum Vittad.) is a 'cult-food', one of the worldwide recognized icon of the European gastronomy and culture, for which genomic information could act as a knowledge platform to improve its production and environmental persistence. The fruiting body of T. melanosporum is an edible truffle (= hypogeous ascocarp), which is a highly appreciated delicacy for its delicate organoleptic properties (i.e., taste and perfumes).

This fungus belongs to the Ascomycota (Pezizales; Tuberaceae). It is endemic to calcareous soils in southern Europe and found in symbiotic association with roots of deciduous trees, mostly oaks and hazelnut trees.

The worldwide demand for this delicacy has fuelled intense efforts at cultivation. Identification of processes that condition and trigger fruit body and symbiosis formation, ultimately leading to efficient crop production will be facilitated by a thorough analysis of truffle genomic traits. To elucidate the genetic basis of these traits, we have sequenced the nuclear genome of the strain Mel28 harvested in Provence in Southeastern France. This is the first symbiotic ascomycete and edible mushroom genome to be sequenced.

The haploid genome of T. melanosporum is by far the largest and most complex fungal genome sequenced so far with ~125 megabases (Mb). This expansion results from a proliferation of repeated transposable elements accounting for ~58% of the genome. In contrast, this genome only contains ~ 7,500 protein-coding genes with very rare multigene families. It lacks large sets of carbohydrate cleaving enzymes, but a few of them involved in degradation of plant cell walls are induced in symbiotic tissues. Analysis of the genome has provided unprecedented insights into the molecular bases of symbiosis, sex and fruiting in the Perigord Black truffle. It will be a major step in moving truffle research into the realm of ecosystem science, nothing to say about the exceptional social and cultural impact of a deeper understanding of the genome of one of the worldwide recognized icons of European gastronomy and culture.

TuberDB contains predicted gene models from the genome sequencing and tentative consensus (TCs) assembled from >100,000 Sanger ESTs representing the transcriptome of T. melanosporum. You could navigate the genome by using the Genome Browser. Here, position of Illumina Solexa tags from RNA-Seq transcript profiling could be displayed by activating the 'solexa tags' track.

The French-Italian Tuber Genome Consortium includes teams from the INRA, Genoscope, CNRS, and several French and Italian universities (Nancy, Marseilles, Torino, Parma, Perugia, Parma, ...).

Publication: Martin et al. (2010) Périgord black truffle genome uncovers evolutionary origins and mechanisms of symbiosis. Nature. doi:10.1038/nature08867.

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