The present invention relates generally to a genetic sequence encoding a polypeptide having methyltransferase activity and the use of the genetic sequence and/or the polypeptide to modify one or more phenotypic characteristics of a plant. More particularly, the methyltransferase of the present invention acts on flavonoids, preferably wherein the flavonoid is an anthocyanin. Even more particularly, the present invention relates to a polypeptide having S-adenosyl-L-methionine:anthocyanin 3'-O-methyl-transferase or S-adenosyl-L-methionine:anthocyanin 3',5'-O-methyltransferase activity. The present invention still further provides a genetic sequence encoding a polypeptide having methyltransferase activity derived from Petunia, Torenia Fuchsia or Plumbago or botanically related plants. The instant invention further relates to antisense and sense molecules corresponding to all or part of the subject genetic sequence as well as genetically modified plants as well as cut flowers, parts, extracts and reproductive tissue from such plants.