Abstract: Using the mTAIL-PCR method, we have isolated the two CYC-like genes, SiCYC1A and SiCYC1B, from zygomorphic and actinomorphic cultivars of Saintpaulia ionantha respectively in Gesneriaceae. The two genes, SiCYC1A and SiCYC1B, from the zygomorphic cultivar both contain the whole regulation domain, i.e. TCP and R domains. Therefore, they should be functional in the floral symmetry establishment, homologous with CYC in Antirrhinum majus. Unexpectedly, the two genes from the actinomorphic cultivar are identical to those from the zygomorphic in DNA sequence, respectively. Based on comparative analysis of the molecular alteration at CYC-like genes, which are responsible for the morphological transformation from zygomorphy to actinomorphy, we suggest that the two closely related genes SiCYC1A and SiCYC1B might be regulated by a common upstream regulator, whose change would result in silence of both SiCYC1A and SiCYC1B in controlling the development of the adaxial and lateral organs in a flower. In addition, an mTAIL-PCR method was shown to have the technological advantages of the unknown sequence for isolation.

Key words: CYC-like gene, whole gene, Saintpaulia ionantha, mTAIL-PCR, upstream regulator