REDUCTION OF DUPLICATION IN A BRASSICA-OLERACEA GERMPLASM COLLECTION

To reduce the number of accessions in the Brassica oleracea collection of the Centre for Genetic Resources The Netherlands (CGN) groups of a ccessions were bulked. Accessions in a group were selections from the same landrace or old variety, and were chosen, with the help of crop e xperts, on the basis of their history and morphology. Since this appro ach was received rather sceptically in the genebank community, a genet ical analysis of some of the groups and their components (named variet ies) was made to justify the procedures. A selection of white cabbage and Brussels sprouts, representing two crop types of B. oleracea, was made: eleven white cabbage groups comprising 43 components, and nine B russels sprouts groups comprising 24 components. Each group and all of its components were described on the basis of electrophoresis of nine isoenzymes on 30 plants. Most components were rightly classified; 16 percent were misclassified. All these misclassifications were within s imilar groups. It could be concluded that pooling of the components in cluded in this study was justified. In two cases the isozymic patterns suggested that the groups could even have been larger. Only in the ca se of the two groups of Brussels sprouts 'Bedfordshire' this was a rea l option. In the other case involving the white cabbage groups 'Langed ijker Bewaar Gewoon', 'Langedijker Bewaar Graag' and 'Late Herfstdeen' this was not an option since these landraces, although having a commo n genetic background, clearly have a distinct identity as defined by m orphology and history.