Abstract
Blue/violet flowers often contain delphinidin based anthocyanins that contain plural aromatic acyl groups (polyacylanthocyanins). Gentian contains a polyacylanthocyanin, gentiodelphin (delphinidin 3-glucosyl-5, 3'-biscaffeoylglucoside), that exhibits stable blue color. Yoshida et al. (2000) showed that the color was derived from the intramolecular stacking by the two caffeoyl groups and that the caffeoyl group at 3' -position mainly contributes to the stacking. The genes encoding anthocyanin acyltransferases have been isolated from gentian, perilla and so on. However, the gene encoding the enzymes that catalyze the transfer of an acyl group to the B-ring has not been isolated. Extensive investigation of gentian anthocyanin 5- acyltransferase (Fujiwara et al., 1999) enabled us to find that this enzyme is 3' , 5-acyltransferase that acylates both 3' and 5-glucose. We have also revealed that the acylation at 5-position proceeds to that at 3' -position. The gene is useful to produce the polyacylated anthocyanin to engineer blue flowers.
