Glucose Oxidation during Shoot Initiation in Tobacco Callus Cultures

Involvement of the Embden-Meyerhof Parnas and the pentose phosphatepathways in glucose oxidation in glucose oxidation in tobaccocallus was examined. Marked changes in the activities of glucokinase,aldolase, glucose-6-phosphate dehydrogenase, and phosphogluconatedehydrogenase were observed during culture of tobacco callusunder shoot-forming and non-shoot-forming conditions. Activitiesof these enzymes were higher in shoot-forming tissue than innon-shoot-forming tissue. Furthermore, the activities of thepentose phosphate pathway enzymes showed greater differencesthan those of the Embden-Meyerhof-Parnas pathway. Confirmationof these findings was obtained by investigating the contributionsof ¹⁴C from [14C-1]- and [¹⁴C–6]-glucose to CO2 released.The significance of these findings on glucose oxidation in relationto the shoot-initiation process are discussed.