A transgenic plant is prepared by a method in which a plant cell is transformed with a chimaeric gene comprising a promoter and a gene encoding a polypeptide which displays the activity of an enzyme which regulates the amount of a metabolic intermediate in glycolysis or in a pathway for the synthesis or degradation of starch, sucrose or reducing sugar from a glycotyltic intermediate. In stored potatoes the subject of the invention an increased level of phosphofructokinase results in reduced accumulations of sugars in the tubers. <IMAGE>
