Provided is a polynucleotide encoding a protein that exhibits activity for transferring a sugar to a hydroxyl group at position 7 of a flavone, particularly flavone 4′-glucoside, wherein the polynucleotide is selected from the group consisting of: (a) a polynucleotides comprising the base sequence of SEQ ID NO: 1 or SEQ ID NO: 5; (b) a polynucleotide that hybridizes, under stringent conditions, with a polynucleotide comprising the base sequence complementary to the base sequence of SEQ ID NO: 1 or SEQ ID NO: 5; (c) a polynucleotide encoding a protein comprising the amino acid sequence of SEQ ID NO: 2 or SEQ ID NO: 6; (d) a polynucleotide encoding a protein comprising an amino acid sequence in which one or more amino acids have been deleted, substituted, inserted, and/or added in the amino acid sequence of SEQ ID NO: 2 or SEQ ID NO: 6.
