Abstract
In PAP1-overexpressing mutants, anthocyanins and quercetin-type flavonol glycosides are specifically over-accumulated. Microarray analyses revealed that expressions of 38 genes are higher than in wild type. Acyltransferases (ATs), whose functions are remained undetermined, are up-regulated and expected to be involved in modification of anthocyanins.
Recombinant AT proteins were expressed in Escherichia coli. Malonyltransferase activity was detected with recombinant protein encoded by AT1. The recombinant protein accepted cyanidin 3,5-diglucoside but not cyanidin 3-glucoside as a acyl-acceptor. Coumaroyltransferase activity was detected with recombinant proteins encoded by AT2 and AT3. Although it is not possible to distinguish the transcripts of those 2 genes with microarray analysis, expressions of both genes were confirmed to be higher in pap1-D mutant than in wild type with semi-quantitative RT-PCR. Flavonoids accumulated in knockout mutants of each gene will be analyzed to confirm the functions of those AT genes in planta.
