Cytogenetic analysis of diploid Brassica species

The chromosomes of Brassica species are small and poorly differentiated, and their identification is extremely difficult using conventional cytogenetic methods. Progress in molecular analysis of Brassica species requires cytogenetic maps of their chromosomes. Chromosome-specific markers are needed to distinguish particular pairs of homologous chromosomes and for karyotyping. In this study, three morphological groups of chromosomes in B. campestris (genome A) and B. oleracea (genome C) and two in B. nigra (genome B) were distinguished by the morphometric features of the chromosomes, based upon arm ratio and absolute length. Using fluorescence in situ hybridization and differential stainings it was possible to establish further markers for five pairs of chromosomes in genome A, three in genome B and two in genome C, and to present idiograms of the chromosomes for three diploid Brassica species. However, for clear identification of all chromosome pairs more cytogenetic markers are needed.