SYSTEMATIC IMPLICATIONS OF CHLOROPLAST DNA VARIATION IN LEPIDIUM SECTIONS CARDAMON, LEPIOCARDAMON AND LEPIA (BRASSICACEAE)

Abstract

Chloroplast DNA restriction site variation was examined among Lepidium taxa usually classified in sects. Lepia, Lepiocardamon and Cardamon. By using 15 restriction endonucleases, filter hybridization experiments, and comparative mapping procedures, a total of 119 variable restriction sites was detected. Of these, 56 were phylogenetically informative and were used in a cladistic analysis. The resulting phylogenetic tree agrees with results derived from morphology, isozyme electrophoresis and the analysis of glucosinolates. The data suggest: 1) The recognition of sect. Lepia, and 2) that sect. Lepiocardamon has close relationships to sect. Cardamon and that both should be amalgamated. Low rates of interspecific chloroplast DNA sequence divergence in sect. Lepia correlated well with morphological data and isoelectric focusing analysis of Rubisco, suggesting that taxa of sect. Lepia are closely related and most likely have diversified recently.