Glucosyltransferase that catalyzes the formation of 1-O-beta-D-glucose esters with hydroxybenzoic acids and cinnamic acid including its derivatives as preferred glucosyl acceptors. Has significant activity with gallic acid (3,4,5-trihydroxybenzoic acid), 3,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, cinnamic acid, sinapic acid, coumaric acid, caffeic acid and ferulic acid in vitro. Gallic acid is the predicted native substrate of the enzyme, which thus catalyzes the formation of 1-O-galloyl-beta-D-glucose, the first committed step of hydrolyzable tannins (HTs) biosynthesis, with punicalagin isomers being the major HTs of pomegranate. Catalyzes the formation of flavonoid glucosides with genistein, apigenin and luteolin in vitro. Has low activity with benzoic acid, 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, naringenin and quercetin. No activity with catechol, resveratrol, chlorogenic acid, catechin and epicatechin (building blocks of proanthocyanidins) or cyanidin, delphinidin and pelargonidin (the three anthocyanidins). 3,4,5-trihydroxybenzoate + UDP-alpha-D-glucose = 1-O-galloyl-beta-D-glucose + UDP 3,4-dihydroxybenzoate + UDP-alpha-D-glucose = 1-O-(3,4-dihydroxy-benzoyl)-beta-D-glucose + UDP 4-hydroxybenzoate + UDP-alpha-D-glucose = 4-(beta-D-glucosyloxy)benzoate + H(+) + UDP (E)-cinnamate + UDP-alpha-D-glucose = 1-O-(trans-cinnamoyl)-beta-D-glucose + UDP E-sinapate + UDP-alpha-D-glucose = 1-O-(trans-sinapoyl)-beta-D-glucose + UDP (E)-4-coumarate + UDP-alpha-D-glucose = 1-O-(trans-4-coumaroyl)-beta-D-glucose + UDP (E)-caffeate + UDP-alpha-D-glucose = 1-O-[(E)-caffeoyl]-beta-D-glucose + UDP (E)-ferulate + UDP-alpha-D-glucose = 1-O-[(E)-feruloyl]-beta-D-glucose + UDP genistein + UDP-alpha-D-glucose = genistein 7-O-beta-D-glucoside + H(+) + UDP apigenin + UDP-alpha-D-glucose = apigenin 7-O-beta-D-glucoside + H(+) + UDP luteolin + UDP-alpha-D-glucose = H(+) + luteolin 7-O-beta-D-glucoside + UDP kcat is 0.55 sec(-1) with gallic acid as substrate. kcat is 0.6 sec(-1) with 4-hydroxybenzoic acid as substrate. kcat is 1.35 sec(-1) with 3,4-dihydroxybenzoic acid as substrate. kcat is 0.89 sec(-1) with caffeic acid as substrate. kcat is 0.45 sec(-1) with cinnamic acid as substrate. kcat is 0.44 sec(-1) with coumaric acid as substrate. kcat is 0.66 sec(-1) with ferulic acid as substrate. kcat is 0.44 sec(-1) with sinapic acid as substrate. Optimum pH is 4.5. Activity remains fairly constant between 20-55 degrees Celsius. Active even at 0 degrees Celsius. Highly expressed in leaf. Also expressed in peel, stem, root and aril. No difference in the levels of punicalagin in pomegranate hairy roots in a single RNAi knockdown of this gene. However, double RNAi knockdown of this gene together with UGT84A23 leads to significantly reduced levels of punicalagin and bis-hexahydroxydipheynyl glucose isomers, and to increased levels of galloyl glucosides (ether-linked gallic acid and glucose). Belongs to the UDP-glycosyltransferase family.