Placement of Three Problematic Genera of Gesneriaceae based on Chalcone Synthase (CHS) a Duplicated Nuclear Gene.

The duplicated nuclear gene CHS was used to position three problematic genera within Gesneriaceae. CHS is duplicated in all lineages and forms extensive orthologous-paralogous trees making the placement of genera within the family distinct. Two genera of the tribe Coronanthereae (Sarmienta and Rhabdothamnus) are a monophyletic group within the Gesnerioideae subfamily and this clade is sister to a large orthologous-paralogous subtree containing the majority of new world genera This placement suggests that Coronanthereae does not merit standing as a subfamily but is a tribe circumscribed within Gesnerioideae. The monotaxic tribe Titanotricheae (Titanotrichum) lies between the Coronanthereae and sister to the rest of the new world genera.