and
flavonoid 3-hydroxylase (F3H, Brugliera et al. 1999).
Petunia has two F35H loci, and the Hf1 locus plays
major role (Holton et al. 1993a). Hf1 and Hf2 encode
very similar F35H in terms of their amino acid and
DNA sequences (about 95% identity, Holton et al.
1993a). Wild-type petunia flowers contain acylated
delphinidin-type anthocyanins and flavonols (Figure 1),
and their color is reddish purple (low pH) or violet (high
pH). The flower color becomes redder when the flowers
produce cyanidin-type anthocyanins and/or non-acylated
anthocyanins.