Molecular phylogeny and systematics of the tribe Chorisporeae (Brassicaceae)

Sequence data from nuclear (ITS) and chloroplast (<i>trn</i>L-F) regions for 89 accessions representing 56 out of 64 species from all five genera of the tribe Chorisporeae (plus <i>Dontostemon tibeticus</i>) have been studied to test the monophyly of the tribe and its component genera, clarify its boundaries, and elucidate its phylogenetic position in the family. Both data sets showed strong support for the monophyly of the Chorisporeae as currently delimited, though the position of its tentative member <i>D. tibeticus</i> was not resolved by ITS. <i>Parrya</i> and <i>Pseudoclausia</i> are poly- and paraphyletic with regard to each other, and <i>Chorispora</i> is either polyphyletic or at least paraphyletic (comprising <i>Diptychocarpus</i>) within a weakly supported monophyletic clade. The incongruence in branching pattern among the markers was most likely caused by hybridization and possibly influenced by incomplete lineage sorting. The present results suggest uniting <i>Pseudoclausia</i>, <i>Clausia podlechii</i>, and <i>Achoriphragma</i> with <i>Parrya</i> and transferring <i>P. beketovii</i> and <i>P. saposhnikovii</i> to <i>Leiospora</i> (Euclidieae). We also obtained support for splitting <i>Chorispora</i> into two geographically defined groups, one of which is closer to <i>Diptychocarpus</i>. Both data sets revealed a close relationship of the Chorisporeae to Dontostemoneae, while ITS also indicated affinity to Hesperideae. Therefore, the position of Chorisporeae needs further verification. KeywordsBrassicaceae–Chorisporeae–Generic delimitation–Phylogeny–Parrya.