Meiotic analysis of Danish species of Barbarea (Brassicaceae) using FISH: chromosome numbers and rDNA sites.

PMCs of 5 taxa of Barbarea from Denmark, i.e. B. stricta, B. verna, B. intermedia and B. vulgaris ssp. vulgaris and ssp. arcuata, the latter including the two morphologically, biochemically and cytologically divergent P-(pubescent) and G-(glabrous) types, and two P-xG-type hybrids were subjected to meiotic analysis for numbers of chromosomes and rDNA sites using fluorescent in situ hybridization (FISH). Meiosis was very regular. The chromosome number of all material was n=x=8 in agreement with the general chromosome number of 2n=16 of the genus. A previously suggested chromosome number of 2n=18 of Danish accessions of the P-type of B. vulgaris ssp. arcuata could not be verified. Meiosis of B. intermedia presented one labelled bivalent and one labelled chromosome at diakinesis/metaphase I and metaphase II/anaphase II, respectively. At the same stages two labelled bivalents or chromosomes were observed in the other materials.