‘The ‘black diamond’, the ‘mysterious product of the earth’, the ‘ultimate fungus’ and ‘la grande mystique’ are some of the common names describing the delectable Périgord black truffle (Tuber melanosporum Vitt.). The culture, harvesting and marketing of this highly prized ectomycorrhizal fungus is a world that retains some of the secrets and intrigue of the past. Truffle cultivation is notoriously difficult, in part because of its cryptic life cycle as an underground symbiont, in which the fungus trades nutrients with oak-tree roots. By the end of the 1960s, there had been some success in devising new methods for producing truffle-infected seedlings under controlled conditions in glasshouses by inoculating plants with truffle cultures and spores. After successful plantation in orchards, reliable information on truffle yields and production is very difficult to obtain as a result of under-reporting of harvests, under-the-table marketing practices and a lack of administration records. It appears, however, that the production of truffles, as with other mushrooms, is erratic from year to year (depending on the weather conditions) and tends to decline as a result of global climate change. Decreasing supply and rising market prices have provided a strong incentive for research on truffle cultivation.’ (from my edito)
The February issue of New Phytologist (189: 3) includes a Special Feature dedicated to the Perigord Truffle genome with 7 papers discussing the transcriptome, the repertoire of transcriptional factors, the carbohydrate metabolism, the aroma biosynthesis and the molecular ecology of sex of this ultimate fungus. Another raft of companion papers have been published in Fungal, Genetics & Biology.
To date, genomes of two mutualistic fungal symbionts, the basidiomycete L. bicolor and the ascomycete Tuber melanosporum, have been sequenced. Based on their symbiosis-induced gene networks, evolution of the ectomycorrhizal lifestyle appears to be quite divergent (Plett & Martin, 2011). To better understand the differences between symbiotic lineages and types of symbiosis, our JGI project is aiming to sequence 25 mycorrhizal fungi from different orders. As of today, genomic DNA from Amanita muscaria, Cenococcum geophilum, Hebeloma cylindrosporum, Laccaria amethystina, Oidiodendron maius, Piloderma croceum, Paxillus involutus, Pisolithus microcarpus and P. tinctorius is currently being sequenced using next generation sequencing platforms. Sequencing of Boletus edulis, Cantharellus cibarius, Coltricia cinnamomea, Cortinarius glaucopus, Gymnomyces xanthosporus, Lactarius quietus, Meliniomyces bicolor, Paxillus rubicundulus, Ramaria formosa, Rhizoscyphus ericeae, Scleroderma citrinum, Suillus luteus, Sebacina vermifera, Tomentella sublilacina, Tricholoma matsutake, Tulasnella calospora and Terfezia boudieri will follow in 2011.