Relative expression of CfTPS genes in C. forskohlii tissues. Transcript abundance of CfTPS genes expressed in arbitrary units was measured by quantitative PCR using the translation initiation factor (TIF4a) for normalization. Each value represents the average of three biological replicates, each of which was performed in at least three technical replicates. Ck, Root cork; CS, root cortex and stele; Fl, flowers; St, stems; Lv, leaves.