’jumping genes’ help black truffles adapt to their environment

Black truffles, also known as Périgord truffles, grow in symbiosis with the roots of oak and hazelnut trees. In the world of haute cuisine, they are highly prized for their syrupy sweet flavor. In the world of epigenetics, however, the fungi (Tuber melanosporum) are of major interest for another reason: their unique pattern of DNA methylation, a biochemical process that chemically modifies nucleic acids without changing their sequence. Epigenetics is the study of changes in gene expression caused by mechanisms other than changes in the DNA sequence. A newly published study in the journal Genome Biology by scientists from UCLA and colleagues in Italy, France and Taiwan reports on the truffle's unique genetic makeup. "The fungi have a complex genome, with a preponderance of repetitive and mobile elements," said Simone Ottonello of the laboratory of functional genomics and protein engineering at the University of Parma in Italy. "The genome resembles the composition of the human genome, which also uses reversible methylation — and other mechanisms — to deal with repeated and mobile elements." More than 58 percent of Tuber melanosporum's genetic material is made up of so-called "jumping genes," transposable genetic elements, or transposons, that can replicate and paste themselves throughout the genome.