Polyphyletism of Celastrales deduced from a chloroplast noncoding DNA region.

In a previous study we examined the phylogeny of four families related to the angiosperm order Celastrales based on chloroplast rbcL 5' flanking sequences. We have added here several additional dicots, sampled from 6 of the 7 families of Celastrales sensu Cronquist and 19 putatively related genera. Based on a cladistic analysis of these DNA sequences, the order Celastrales appears polyphyletic: it is here restricted to Celastraceae (including Hippocrateaceae and Brexia) with Parnassia as sister; Aquifoliaceae plus Helwingia are included in Asteridae. Neither Salvadoraceae nor Geissolomataceae, Icacinaceae, Phellinaceae, Aextoxicaceae, Corynocarpaceae, Dichapetalaceae, Stackhousiaceae, or Goupiaceae are related to Celastrales. The usefulness of this noncoding region is discussed and the influence of the A + T content of neighboring bases on the increase of transversions is also observed as previously shown in chloroplast noncoding regions of monocots.