Truffle brûlé: an efficient fungal life strategy.

The terms 'brûlé' and 'burnt' are used to describe vegetation-devoid areas of the ground around a range of woody plants interacting with certain truffle species. Increasing interest is currently focused on a systematic search for and study of volatile organic compounds (VOCs) emitted by truffles in the course of their life cycle. These metabolites are now recognized as biochemicals with an important impact on burnt formation. Based on current molecular approaches, Tuber melanosporum is emerging as an aggressive colonizer of the brûlé, dominant in competition with indigenous brûlé-associated organisms, suppressing their richness and biodiversity. There is compelling evidence that mycelia, mycorrhizae, and fruiting bodies of brûlé-forming truffles have evolved diffusible metabolites for their survival, typically characterized as having harmful effects on weeds, impairing seed germination, altering root morphogenesis and plant hormonal balance, or inhibiting the native rhizospheric microflora regularly associated with the brûlé. These effects can be widely interpreted as allelopathic phenomena, and the brûlé may thus be regarded as a promising opportunity to study truffle allelopathy. Considering the outstanding success of the genome analysis in T. melanosporum, we are facing a very difficult task to proceed from the molecular to the ecological level.