Phylogenomics of the olive tree (Olea europaea) disentangles ancient allo- and autopolyploidizations in Lamiales.

Abstract

BackgroundPolyploidization is one of the major evolutionary processes that shape eukaryotic genomes, being particularly common in plants. Polyploids can arise through direct genome doubling within a species (autopolyploidization) or through the merging of genomes from distinct species after hybridization (allopolyploidization). The relative contribution of either mechanism in plant evolution is debated. Here we used phylogenomics to dissect the tempo and mode of duplications in the genome of the olive tree (Olea europaea), one of the first domesticated Mediterranean fruit trees.\n\nResultsOur results depict a complex scenario involving at least three past polyploidization events, of which two -at the bases of the family Oleaceae and the tribe Oleeae, respectively- are likely to be the result of ancient allopolyploidization. A more recent polyploidization involves specifically the olive tree and relatives.\n\nConclusionOur results show the power of phylogenomics to distinguish between allo- and auto- polyplodization events and clarify the conundrum of past duplications in the olive tree lineage.