Isolation of an acyl-glucose-dependent anthocyanin 7-O-glucosyltransferase from the monocot Agapanthus africanus.

A cDNA encoding an acyl-glucose-dependent anthocyanin 7-O-glucosyltransferase (AaAA7GT) was isolated from Agapanthus africanus petals; this is the first AAGT identified in a monocot. Peak expression of AaAA7GT in developing A. africanus petals occurred before the flowering stage, and was later than found previously for other anthocyanin biosynthetic genes. Analysis of recombinant proteins showed AaAA7GT had strict substrate preference for anthocyanidin 3-O-glycosides. The AaAA7GT amino acid had high sequence similarity to glycoside hydrolase family 1 (GH1) proteins, which typically act as β-glycosidases. A phylogenetic analysis of amino acid sequences suggested that AAGTs were derived from glycosidase early in the angiosperm lineage.