The gene cycloidea (cyc) has been documented in its control of bilateral floral symmetry in Antirrhinum and Linaria. The role of cyc in the control of floral symmetry in other genera and its phylogenetic potential have not been widely explored. Recent work on subfamily Cyrtandroideae of Gesneriaceae has revealed a cyc homolog named Gcyc. At least two duplicates of this gene are known from Cyrtandroideae. Phylogenetic analyses using these sequences at the intra- and intergeneric levels have shown that Gcyc can provide data of phylogenetic utility. Using primers designed to amplify Gcyc from diverse Gesneriaceae, one copy of Gcyc from most taxa was isolated. In order to amplify Gcyc from additional (problematic) taxa, a new, internal 5' primer was designed. Sequences were obtained from all tribes and many genera of Gesnerioideae (including genera with non-bilateral floral symmetry). In only two genera (Fieldia and Negria) have duplications of Gcyc been found. Sequences are readily alignable and show less variability than found in subfamily Cyrtandroideae on the basis of indels. There is no evidence for frame shift or stop codon mutations, implying that gene function is maintained across all taxa. Parsimony and maximum likelihood are congruent with previous analyses of relationships among tribes and genera in Gesnerioideae.

Key words: cycloidea, Gcyc, Gesneriaceae, Gesnerioideae, phylogeny