Disclosed are a method for controlling flavonoid synthesis in a chrysanthemum plant or non-chrysanthemum plant by genetic recombination technology using a transcriptional regulatory region useful for altering flower color, a method for modifying anthocyanins, a method for producing a chrysanthemum plant or non-chrysanthemum plant containing modified anthocyanins in the petals thereof, and a chrysanthemum plant or non-chrysanthemum plant, progeny thereof, or vegetatively propagated products, part or tissue thereof transformed with the regulatory region. In the method according to the present invention, an expression vector or expression cassette containing a transcriptional regulatory region of perilla anthocyanin 3-acyltransferase gene, such as a nucleic acid containing the nucleotide sequence indicated in SEQ ID NO. 1, or a transcriptional regulatory region of pansy F3'5'H gene, such as the nucleotide sequence indicated in SEQ ID NO. 15, is used.