Genome sequencing supports a multi-vertex model for Brassiceae species

- R. sativus has a similar position in genome evolution as that of Brassicas.
- Brassica “triangle of U” was extended to an open system as a multi-vertex model.
- Model multi-vertex suggests the importance of paleopolyploidization to Brassiceae speciation.
- The model describes potentials of utilizing more Brassiceaes to create new crops.

The economically important Brassica genus is a good system for studying the evolution of polyploids. Brassica genomes have undergone whole genome triplication (WGT). Subgenome dominance phenomena such as biased gene fractionation and dominant gene expression were observed in tripled genomes of Brassica. The genome of radish (Raphanus sativus), another important crop of tribe Brassiceae, was derived from the same WGT event and shows similar subgenome dominance. These findings and molecular dating indicate that radish occupies a similar evolutionary origin as that of Brassica species. Here, we extended the Brassica “triangle of U” to a multi-vertex model. This model describes the relationships or the potential of using more Brassiceae mesohexaploids in the creation of new allotetraploid oil or vegetable crop species.