Fig. 4.

5′-flanking sequences of flavonoid biosynthetic genes from gentian and transient expression assay. (A) Structures of the promoters of Gt CHS, Gt FNSII, Gt F3′H, and GtF3′5′H. Filled, striped, and dotted boxes indicate MYB recognition elements, vertebrate MYB (Urao et al., 1993), P-recognition element (Grotewold et al. 1994), and an ACGT-containing element (ACE, Hartmann et al., 1998, 2005), respectively. The positions upstream of the transcription initiation site (arrow) are indicated as numerals above the filled triangles. The coding regions are indicated as open boxes. (B) Effect of GtMYBP3 and GtMYBP4 on promoter activities of four flavonoid biosynthetic genes. Transient expression assays were performed by transfecting the reporter and effector plasmid DNA into the protoplasts from Arabidopsis T87 cells. GtCHSpro-LUC, GtFNSIIpro-LUC, GtF3′Hpro-LUC, or GtF3′5′Hpro-LUC were used as reporters, and p35Spro-GtMYBP3, p35Spro-GtMYBP4, or pBI221 (negative control) were used as the effector. p35Spro-RLUC was also used as a transformation control. The promoter activation activities are indicated as relative values compared with that of the negative control. Asterisks indicate statistically significant differences between the means for negative control (pBI221) and tested genes, as judged by Student′s t-test (P < 0.01).