Research teams at INRA and the CEA have sequenced the genome of pedunculate oak (Quercus robur). It is the first time a Quercus species – a very common one in the northern hemisphere – has been sequenced. This work provides insight into the adaptation mechanisms of trees to changes in their environment and will be helpful in predicting their reactions to climate change. The findings have been published in a presubmission paper in Molecular Ecology Resources (open access) before a final publication in the next few months.
The emblematic pedunculate oak tree (Quercus robur) is part of the largest botanical section of the Quercus genus: the White Oak, of which there are 200 species, is found in Europe, Asia and America. A consortium of INRA Bordeaux-Aquitaine, in partnership with Genoscope, the national sequencing centre of the CEA, has recently sequenced the genome of the pedunculate oak. Three years of work have allowed the deciphering of all genetic information carried by its 12 pairs of chromosomes. The consortium has characterised 50,000 genes and estimates that half of the 1.5 billion base pairs of the genome are composed of repeated elements. This is a first for a species of the Quercus genus, which is economically, environmentally, and even culturally important in many countries.
Sequencing the genome of the pedunculate oak has provided a unique gateway to analysing and understanding gene function in this iconic tree. Its genome can be used as a reference for other white oak species and for more distant species of the family Fagaceae (Chestnut or Beech). Internal regulation in very long-lived species exposed to strong annual climate variations and extreme events over the course of their existence can be studied. This research will also help identify which genes are involved in environmental adaptation and in symbiosis between tree roots and mycorrhizal fungi (such as truffle mycelium). Through this work it also possible to identify the genes behind the biosynthesis of wood extracts such as tannins and whisky lactone, which give flavour and taste to wines and spirits. In terms of evolution, decoding the oak genome will allow scientists to analyse local adaptation and speciation processes more accurately. These processes explain the diversity of trees, which have colonised very diverse habitats.
This work is a major breakthrough in our understanding of the biology, genetics and evolution of trees which will contribute greatly to future research on genomic structure and function in these perennial species. In addition to academic knowledge, this research creates opportunities in applied dealing with the many social factors affecting the evolution of forests.