Contribution to ITS phylogeny of the Brassicaceae, with special reference to some Asian taxa

Abstract

Sequence data from the nuclear ribosomal internal transcribed spacer (ITS) region for 189 accessions representing 184 species in 121 genera of Brassicaceae were used to determine monophyly of tribes and genera, tribal boundaries, and component genera. Parsimony analysis and Bayesian inference suggest that the tribes Camelineae and Arabideae are polyphyletic and should be subdivided into smaller tribes. The study also supports the recent recognition of the new tribes Aphragmeae, Biscutelleae, Buniadeae, Calepineae, Conringieae, Dontostemoneae, Erysimeae, Malcolmieae, Megacarpaeeae, and Turritideae. The data argue for the placement of Borodinia in the tribe Boechereae, Litwinowia and Pseudoclausia in the Chorisporeae, Atelanthera and Streptoloma in the Euclidieae, and Megacarpaea and Pugionium in the Megacarpaeeae, and exclusion of Asperuginoides, Didymophysa, and Ptilotrichum from the Alysseae, Macropodium, Pseudoturritis, and Stevenia from the Arabideae, and Crucihimalaya, Irenepharsus, Pachycladon, and Turritis from the Camelineae. Finally, the findings support the expansion of Stevenia to include both Berteroella and Ptilotrichum, Sterigmostemum to include Oreoloma and one species of Anchonium, Crucihimalaya to include Transberingia and several species of Arabis, and Parrya to include Pseudoclausia. The data also suggest that Calymmatium and Olimarabidopsis may be congeneric.