An object of the present invention is to provide a method for producing a flavone wherein a malonyl group is added to a glucose at position 7 using a polynucleotide encoding a protein having activity that transfers a malonyl group to position 6 of the glucose at position 7 of flavone 7-glucoside, and create a plant variety having a modified flower color, and preferably a flower color that is bluer than that of existing varieties, by containing as a co-pigment a flavone wherein a malonyl group has been added to the glucose at position 7. A polynucleotide is used that is selected from the group consisting of, for example: (a) a polynucleotide consisting of the base sequence of SEQ ID NO: 1； (b) a polynucleotide that hybridizes under stringent conditions with a polynucleotide consisting of the base sequence complementary to the base sequence of SEQ ID NO: 1 and encodes a protein having activity that transfers a malonyl group to position 6 of the glucose at position 7 of flavone 7-glucoside； (c) a polynucleotide that encodes a protein consisting of the amino acid sequence of SEQ ID NO: 2； and, (d) a polynucleotide encoding a protein that consists of an amino acid sequence wherein one or a few amino acids have been deleted, substituted, inserted and/or added in the amino acid sequence of SEQ ID NO: 2 and has activity that transfers a malonyl group to position 6 of the glucose at position 7 of flavone 7-glucoside.
