Properties and genetic control of four methyltransferases involved in methylation of anthocyanins in flowers of Petunia hybrida.

Four S-adenosyl-L-methionine:anthocyanin-3',5'-O-methyltransferases in flowers of Petunia hybrida were separated using the chromatofocusing technique. Each methyltransferase is controlled by one of the methylation genes Mt1, Mt2, Mf1 or Mf2. Molecular weight, pH-activity optimum, isoelectric point, several kinetic properties and the behaviour in the presence of Mg(2+), ethylenediaminetetraacetic acid and S-adenosyl-L-homocysteine of each of the four enzymes were determined. The methylation in vitro of delphinidin 3-(p-coumaroyl)-rutinosido-5-glucoside reflected the accumulation patterns of methylated anthocyanins in vivo and established the regulatory role of methyltransferases in vivo.