Glycosyltransferase involved in the biosynthesis of aurones, plant flavonoids that provide yellow coloration to flowers. 2',4,4',6'-tetrahydroxychalcone + UDP-alpha-D-glucose = 2',4,4',6'-tetrahydroxychalcone 4'-O-beta-D-glucoside + H(+) + UDP 2',3,4,4',6'-pentahydroxychalcone + UDP-alpha-D-glucose = 2',3,4,4',6'-pentahydroxychalcone 4'-O-beta-D-glucoside + H(+) + UDP Expressed in petals. Not detected in stems and leaves. Belongs to the UDP-glycosyltransferase family.