nins: pelargonidins (orange/red), cyanindins (blue/magenta/red), and delphinidins (blue/purple). The production of pelargonidins requires just the core enzymes, but the production of cyanidins and delphinidins depends on 2 enzymes [flavonoid 3′-hydroxylase (F3′H) and flavonoid 3′5′-hydroxylase (F3′5′H)] that add 1 or 2 hydroxyl groups, respectively, on the β-ring of the product of F3H (Grotewold, 2006; Rausher, 2008). Subsequently, DFR, ANS, and UFGT act to produce anthocyanins, which are then transported into the vacuole where they accumulate and produce visual colors (Fig. 2.3).
Rausher (2008) has described general trends in flower color evolution: shifts are generally blue to red or from producing anthocyanin to not, although exceptions do occur. Considering the biochemical pathway for anthocyanins, Rausher pointed out that these trends likely arise because mutations causing loss of function are more likely than those causing