Classical Breeding and Genetic Analysis of Vegetable Brassicas
Different Brassica vegetables have different origins and breeding history. It is believed that most of the present day cultivated forms of B. oleracea have originated from native wild forms, which were found growing originally
in the Atlantic coasts of Europe especially northern Spain, western France, southern and southwestern Britain (Snogerup 1980; Snogerup et al. 1990; Hodgkin 1995; Lázaro and Aguinaglade 1998). Hodgkin (1995) believed that this wild species had been brought to the Mediterranean region from the western Atlantic European coast where selection for different morphological types created the present diverse cultivated forms of B. oleracea. Further, it is believed that all cole crops originated from the Mediterranean regions through mutation and introgression from wild species during evolution or human selection (Swarup and Brahmi 2005; for details of origin see Chapter 1). B. oleracea evolved into a wide range of various subgroups or cultivars that are presently cultivated worldwide for edible roots, leaves, flower stalks or swollen stem. It is shown that plants from different subgroups belonging to this species are closer genetically than morphologically as they hybridize easily among each other. Breeding for different types, forms, quality, duration and other morphological traits by people from different regions created lots of diversity within each subgroup. In the following section the early breeding history of a few major B. oleracea crops are described. The authors adapted most of the contents from the review of Shinohara (1984) for the breeding history due to limited literature from other sources/forms.