Understanding Brassicaceae evolution through ancestral genome reconstruction.

BACKGROUND

Brassicaceae is a family of green plants of high scientific and economic interest, including thale cress (Arabidopsis thaliana), cruciferous vegetables (cabbages) and rapeseed.

RESULTS

We reconstruct an evolutionary framework of Brassicaceae composed of high-resolution ancestral karyotypes using the genomes of modern A. thaliana, Arabidopsis lyrata, Capsella rubella, Brassica rapa and Thellungiella parvula. The ancestral Brassicaceae karyotype (Brassicaceae lineages I and II) is composed of eight protochromosomes and 20,037 ordered and oriented protogenes. After speciation, it evolved into the ancestral Camelineae karyotype (eight protochromosomes and 22,085 ordered protogenes) and the proto-Calepineae karyotype (seven protochromosomes and 21,035 ordered protogenes) genomes.

CONCLUSIONS

The three inferred ancestral karyotype genomes are shown here to be powerful tools to unravel the reticulated evolutionary history of extant Brassicaceae genomes regarding the fate of ancestral genes and genomic compartments, particularly centromeres and evolutionary breakpoints. This new resource should accelerate research in comparative genomics and translational research by facilitating the transfer of genomic information from model systems to species of agronomic interest.