Five glucosyltransferases were cloned by RT-PCR ampliWcation using total RNA from Hieracium pilosella L. (Asteraceae) inXorescences as template. Expression was accomplished in Escherichia coli, and three of the HIS-tagged enzymes, UGT90A7, UGT95A1, and UGT72B11 were partially puriWed and functionally characterised as UDP-glucose:Xavonoid O-glucosyltransferases. Both UGT90A7 and UGT95A1 preferred luteolin as substrate, but possessed diVerent regiospeciWcity proWles. UGT95A1 established a new subgroup within the UGT family showing high regiospeciWcity towards the C-3Ј hydroxyl group of luteolin, while UGT90A7 primarily yielded the 4Ј-O-glucoside, but concomitantly catalysed also the formation of the 7-O-glucoside, which could account for this Xavones glucoside in H. pilosella Xower heads. Semi quantitative expression proWles revealed that UGT95A1 was expressed at all stages of inXorescence development as well as in leaf and stem tissue, whereas UGT90A7 transcript abundance was nearly limited to Xower tissue and started to develop with the pigmentation of closed buds. Other than these enzymes, UGT72B11 showed rather broad substrate acceptance, with highest activity towards Xavones and Xavonols which have not been reported from H. pilosella. As umbelliferone was also readily accepted, this enzyme could be involved in the glucosylation of coumarins and other metabolites.