This inventions provides an isolated protein or polypeptide having activity in the synthesis of proanthocyanidin (PA) polymer from epicatechin or catechin in plants, and which is not naturally regulated by the TT2 or TT8 regulators, or a fragment comprising at least about 10 contiguous amino acids derived from said protein or polypeptide, particularly TDS1, TDS2, TDS3, TDS4, TDS5, or TDS6 protein, or fragment thereof. Also provided are nucleic acid encoding such proteins or polypeptides; plant cells and plants containing and expressing such nucleic acids; antibodies that bind to such proteins or polypeptides; and related methods.