EXPRESSION OF AN ANTIRRHINUM-MAJUS UDP-GLUCOSE-FLAVONOID-3-O-GLUCOSYLTRANSFE TRANSGENE ALTERS FLAVONOID GLYCOSYLATION ACID ACYLATION IN LISIANTHUS (EUSTOMA-GRANDIFLORUM GRISE)

A binary vector containing an Antirrhinum majus UDP-glucose:flavonoid- 3-O-glucosyltransferase (UFGT) cDNA under the control of the cauliflow er mosaic virus 35S promoter was used to transform lisianthus (Eustoma grandiflorum Grise.). Of four independent transgenic lines recovered, one produced high levels of the UFGT transcript and synthesized 3-O-g lucosylated anthocyanins novel to lisianthus, as well as enhanced leve ls of 3-O-glucosylated flavonols. The novel 3-O-glucosylated anthocyan ins accounted for approximately 30% of the total anthocyanins in the p etals. The level of 3-O-glucosylated flavonols increased by approximat ely 4.8x, representing a change from the production of 3-O-galactosyla ted flavonols to 3-O-glucosylated flavonols of approximately 32%. In a ddition, the increase in glucosylation of the flavonols resulted in a corresponding decrease in acylation. Modifications at other positions of the flavonoid nuclei were unaffected. The results indicate that in lisianthus there is a high specificity shown by some flavonoid modifyi ng enzymes, such as that for flavonol acylation, while other enzymes, such as those involved in modifications at the C-5 of the anthocyanin, are more flexible in their choice of substrate. The results also prov ide information on the role of flavonoid glycosylation and acylation i n copigmentation in lisianthus. (C) 1997 Elsevier Science Ireland Ltd.