Characterization of anthocyanin p-coumaroyltransferase in flowers of Iris ensata

Malvidin and petunidin 3 -(p-coumaryl)rhamnosylglucoside-5-glucosides as we ll as nonacylated 3-rhamnosylglucoside-5-glucoside of these anthocyanidins were detected as major anthocyanins in cyanic flowers of li is ensata. Enzy me extracts from flower buds of this plant analyzed the transfer of the p-c oumaroyl moiety from p-coumaroyl-CoA to both the anthocyanidin 3-rhamnosylg lucoside and 3-rhamnosylglucoside-5-glucoside to form the anthocyanidin 3-( p-coumaroyl) rhamnosylglucoside and 3-(p-coumaroyl) rhamnosylglucoside-5-gl ucoside, at a ratio of ca. 1 to 4, respectively. The activities of this enz yme were also examined for various cyanic and acyanic cultivars, in additio n to the characterization of the p-coumaroyltransferase. The sequence of ac ylation and 5-glucosylation in the anthocyanin biosynthesis of this plant i s discussed. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.