Abstract: We isolated and characterized two CYC-like genes from Oreocharis benthamii Clark (Gesneriaceae) in order to investigate their expression patterns. Phylogenetic analysis demonstrates that the two CYC-like genes, ObCYC1 and ObCYC2, belong to GCYC1 and GCYC2 clades in Gesneriaceae, respectively. Gene-specific RT-PCR results show that they have different spatio-temporal expression patterns. ObCYC1 is mainly expressed in the adaxial region of developing flowers as CYC is in Antirrhinum majus. The expression pattern of ObCYC1 demonstrates its basic function of controlling the adaxial floral organ development that is similar to that of CYC in Antirrhinum, which is in correlation with their conserved function domains, i.e. TCP and R domains. However, ObCYC1 is likely to repress the growth of both the adaxial petals and adaxial staminode. In addition, the weakened expression of ObCYC1 near flowering is correlated with the flower morphology of Oreocharis which is characteristic of weak zygomorphy. ObCYC2 exhibits a remarkable differentiation in protein sequence of TCP and R domain in comparison with those of ObCYC1 and CYC. Correlatively, ObCYC2 is inactive in floral tissue. This unique feature of ObCYC2 needs to be investigated by further comparative study both in expression and function in order to understand its basic function and evolutionary pathway in Gesneriaceae and related families.

Key words: CYCLOIDEA, expression pattern, floral symmetry, Gesneriaceae, Oreocharis benthamii