Data from: Buxus and Tetracentron genomes

Ancient whole-genome duplications (WGDs) characterize many large clades of
angiosperms, including angiosperms themselves. Prominently, the core
eudicot clade accommodates 70% of all angiosperms and shares ancestral
hexaploidy, termed gamma. Gamma arose via two WGDs that occurred early in
eudicot history; however, the relative timing of these is unclear, largely
due to the lack of high-quality genomes among early-diverging eudicots. We
provide complete genomes for Buxus sinica (Buxales) and Tetracentron
sinense (Trochodendrales), representing the lineages most closely related
to core eudicots. We show that Buxus and Tetracentron are both
characterized by independent WGDs, resolve relationships among
early-diverging eudicots and their respective genomes, and use a new
pipeline (RACCROCHE) to reconstruct ancestral genome structure at three
key phylogenetic nodes of eudicot diversification. Our reconstructions
indicate genome structure remained relatively stable during early eudicot
diversification, and reject hypotheses of gamma arising via inter-lineage
hybridization between ancestral eudicot lineages, involving, instead, only
stem lineage core eudicot ancestors.