Figure 5. Hypothesized time of events for the evolution of the Vitis genome.

The evolution of this genome is proposed to have followed two steps leading to hexaploidisation starting from a paleotetraploid state. In the text, a second scenario is discussed in light of the cytological data for the Rosa canina. The same two steps can be hypothesised, with Va and Vc genomes first coexisting in the same nucleus but not exchanging genetic material, and later fusing to generate the hexaploid state. In such a case, polyploidization probably occurred at an intermediate time between 100 and 60 mya.