Glucosinolates (GLSs) are found in Brassica vegetables. Examples of these sources include cabbage, Brussels sprouts, broccoli, cauliflower and various root vegetables (e.g. radish and turnip). A number of epidemiological studies have identified an inverse association between consumption of these vegetables and the risk of colon and rectal cancer. Animal studies have shown changes in enzyme activities and DNA damage resulting from consumption of Brassica vegetables or isothiocyanates, the breakdown products (BDP) of GLSs in the body. Mechanistic studies have begun to identify the ways in which the compounds may exert their protective action but the relevance of these studies to protective effects in the human alimentary tract is as yet unproven. In vitro studies with a number of specific isothiocyanates have suggested mechanisms that might be the basis of their chemoprotective effects. The concentration and composition of the GLSs in different plants, but also within a plant (e.g. in the seeds, roots or leaves), can vary greatly and also changes during plant development. Furthermore, the effects of various factors in the supply chain of Brassica vegetables including breeding, cultivation, storage and processing on intake and bioavailability of GLSs are extensively discussed in this paper.

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For the e.cient application of haploid induction procedures in cabbage breeding\ a su.cient number of regenerants should be achieved in a broad spectrum of genotypes[ However\ the majority of genotypes are somewhat recalcitrant[ The e.ciency of microspore culture was tested by crossing a responsive "17[6 embryos per Petri dish# and a non! responsive "9[0 embryo# cabbage cultivar[ The embryo yield of one progeny was intermediate "07[8# while two were superior to the best parent cultivar "41[8 and 53[9 embryos#[ Thus\ genes for haploid embryogenesis\ present in responsive lines\ can be e}ectively trans! mitted to responsive × non!responsive hybrids[ Abscisic acid!induced desiccation of embryos was used for the e.cient regeneration of plants[ High germination percentages "43[6Ð69[5)# followed by normal plan! tlet development were achieved[ Spontaneous genome doubling mea! sured at the plantlet stage di}ered markedly in untreated genotypes[ The percentage of diploids ranged from 10 to 56)[ The e}ects of two antimitotic drugs applied to freshly isolated microspores were deter! mined in two experiments[ In the _rst experiment\ tri~uralin "9[4 and 0[9 mg:l# had no e}ect on embryo induction while oryzalin partly "9[014Ð9[14 mg:l# or completely "9[4 mg:l# inhibited the formation of embryos[ In the second experiment\ higher concentrations of tri~uralin increased the proportion of diploidized plants[ Application of anti! mitotic drugs to microspores did generally not improve the overall production of haploid plants\ which was higher in an untreated control[

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