Provided is a polynucleotide that encodes a protein having the activity of transferring a sugar to a hydroxyl group at the 4'-position of a flavone. This polynucleotide is selected from the group consisting of: (a) a polynucleotide comprising a base sequence represented by SEQ ID NO: 1； (b) a polynucleotide that hybridizes with a polynucleotide comprising a base sequence complementary to the base sequence represented by SEQ ID NO: 1 under highly stringent conditions, and that encodes a protein having the activity of transferring a sugar to a hydroxyl group at the 4'-position of a flavone； (c) a polynucleotide that encodes a protein comprising an amino acid sequence represented by SEQ ID NO: 2； (d) a polynucleotide that encodes 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 represented by SEQ ID NO: 2, and having the activity of transferring a sugar to a hydroxyl group at the 4'-position of a flavone； and the like.
