Metabolism of 14C-Labeled Sugars Supplied to Tobacco Leaves During Curing Part III)

Abstract

The present investigation was undertaken to obtain the information of the fate of 14C-labeled sugars supplied to tobacco leaf disks during flue-curing of var. Hicks or var. MC and air-curing of var. Daruma. (1) Behavior of glucose-U-14C, fructose-U-14C and sucrose-U-14C supplied to leaf disks of var. Hicks and var. Daruma. When 14C-labeled monosaccharides were supplied for l hr in the dark, sucrose was synthesized to a great extent from them during yellowing process of curing, thereafter they remained in the original form. When sucrose-U-14C was supplied for l hr in the dark, it remained unchanged through successive process of flue-curing, while it was severely broken down to glucose and fructose during browning process of air-curing. (2) Carbon dioxide liberation from leaves and catabolism of glucose in leaves during curing of var. MC and var. Daruma. Carbon dioxide liberation from the leaves of flue-curing had a peak at yellowing process of curing, after that declined, whereas the liberation during air-curing gradually decreased with the process, and continued even at browning process. By the use of the ratio of the label of 14CO2 from glucose-6-14C to that from glucose- 1-14C supplied to leaf disks, it was found that tobacco leaves during curing catabolized glucose to a larger extent via HMP pathway than via EMP pathway and that the partici pation of HMP was increased as the curing progressed. © 1974, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.