ABSTRACT
The genus Brassica is one of the 49-54 genera in the tribe Brassiceae belonging to the crucifer family, and is the genus with the most economically important species within this tribe (Bailey et al. 2006; Beilstein et al. 2006,
Laboratory of Plant Breeding, Wageningen University and Research Center, 6700AJ, Wageningen, The Netherlands; e-mail: Guusje.Bonnema@wur.nl
Chapter 1). The economically important Brassica crop species encompass a great diversity of plants; they are grown as vegetables, fodder, sources of oils and condiments. The morphological variation present within Brassica species is enormous and from several species practically every part of the plant is used by man. This includes the oil and meal of seeds of all oil crops, the leaves in crops like heading cabbages and the leafy types that do not form heads (pakchoi, komatsuna etc.), the terminal and axillary buds in caulifl ower, broccoli and broccoletto, the seed pods in seed stalk mustard, the swollen stems in taitsai and kohlrabi and the swollen roots in turnips and swede. This chapter will describe diversity analyses and molecular taxonomy of oilseed Brassica napus. Since B. napus also includes morphotypes that are cultivated as fodder or vegetables, the diversity analyses will when needed also extend to these crop types. First the origin of B. napus is described, followed by a small section on the B. napus genome, description of the different crop types, and fi nally an overview of studies on the genetic diversity within the species is presented. Additionally a section on germplasm collections and the efforts to create a diversity fi xed foundation set (DFFS) is added. The fi nal part discusses the use of genetic diversity assessments for germplasm conservation and for practical breeding. Here diversity studies of oil types belonging to B. rapa and B. juncea will not be presented; for an overview on the genetic diversity of these species we refer to a recent overview in the book volume on Genetics and Genomics of Vegetable Brassicas of this book series. In the chapter on diversity analysis and molecular taxonomy of Brassica vegetable crops, an overview of the taxonomic position of the Brassica species in the Brassicaceae family is also reviewed.
