Structural characterization of ITS2 and CBC species concept applications in the tribe Coluteocarpeae (Brassicaceae)

The taxonomic utility of internal transcribed spacer 2 (ITS2) secondary structures in different plant groups, as well as in Brassicaceae, has been addressed by many studies. Although characterization and applications of ITS2 secondary structures for the members of main Brassicaceae lineages (Lineages I, II, III, and expanded Lineage II) have been studied, the utility of compensatory base change (CBC) species concept has not been the subject of any studies thus far. In the current study, the ITS2 secondary structures of 49 Coluteocarpeae (expanded Lineage II) specimens were investigated to determine relationships among the species. In addition to the utility of the CBC species concept, the availability of hemi-CBC and nonstructural substitutions (NSTs), which are also used for generic and species delimitation, were tested and discussed.