ABSTRACT
The species of the Brassicaceae form a diverse monophyletic family with over 3,000 members (Koch et al. 2001; Beilstein et al. 2006). The family includes a number of economical important species particularly those from the Brassica genus, and research among this family has tended to focus on the six Brassica species that form U’s triangle (U 1935). Four of these species
1Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, S7N0X2, Canada. ae-mail: Isobel.Parkin@agr.gc.ca *Corresponding author
(Brassica rapa, B. napus, B. juncea and B. carinata) are predominantly grown for oil production while B. oleracea species represent a heterogeneous array of vegetable crops and B. nigra commonly known as black mustard is valued as a condiment. The assortment of valuable phenotypes could result partly from the complex genome structure that has been uncovered within these species. The Brassica species are paleopolyploids evolved from a common ancestor shared with the diminutive plant model Arabidopsis thaliana (Fig. 6-1). The Brassica diploid species, B. oleracea (C genome), B. rapa (A genome) and B. nigra (B genome) have each arisen from a hexaploid ancestor, resulting from a genome triplication event that occurred approximately
Figure 6-1 Phylogenetic relationship of Brassicaceae redrawn from Beilstein et al. (2006), Warwick et al. (2009) and P. Edger et al. (unpubl. data).
