Chromosome numbers in root meristem cells of the seedlings of wild and cultivated Cruciferae species able to hybridize with Brassica napus have been studied. The seedlings of Brassica junceae, Diplotaxis tenuifolia and Raphanum raphanistrum showed exclusively diploid metaphases. Up to 5 % of B. napus and B. cretica seedlings were mixoploids. Diploid cells prevailed among the mixoploids, but hypo– and hyperdiploid ones were observed as well. Near 20 % of B. campestris and R. sativum seedlings were mixoploid, and di– tetraploid chimeras constituted considerable proportion of them. Less than a half of B. nigra seedlings were diploid, while the rest of plants were mixoploid. Among them the seedlings bearing preferentially tetra– and triploid cells dominated. Biological implications and presumable reasons underlying the discovered mixoploidy are discussed.
Keywords: Brassica, mixoploidy