Sugar Transformation in Leaves of Canna Indica

It was previously demonstrated that, when solutions of hexose sugars such as glucose, fructose, or mannose are introduced into green leaves under aerobic conditions, an increase in sucrose is observed (l-3). The sucrose appears to be synthesized at the expense of the monosaccharides. Excised barley leaves infiltrated with 5 per cent glucose or fructose accumulated sucrose to a level of about 6 per cent of dry weight (2). The obvious questions that arise from these infiltration experiments are these: are the infiltrated sugars used per se in the synthesis of sucrose or is the disaccharide formed as a result of the infiltration of unphysiological concentrations of reducing sugars which have altered the metabolism of the leaf in such a way as to cause the synthesis of sucrose from starch or some other storage product? We have undertaken to answer these questions by the use of Cl”-labeled sugars.