The role of changes in enzyme activities in the regulation of carbohydrate dissimilation in potato tuber tissue after wounding or infection with Gibberella zeae

The activities of hexokinase, phosphoglucomutase, phosphoglucoisomerase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase have been determined in the tissue at various distances from the wounded or inoculated surface of potato tuber halves after 1 or 2 days of incubation. Phosphoglucomutase activity was very high when compared to hexokinase activity, and is probably present in great excess. Phosphoglucoisomerase was 3 times as active as gIucose-6-phosphate dehydrogenase which was about 4 times as active as 6-phosphogluconate dehydrogenase. The enzyme activities in healthy tissue and their changes when metabolism was activated by wounding or infection, suggest that the increase of carbohydrate dissimilation and of the pentose phosphate pathway operation might not primarily be governed by the amounts of enzymes in the tissue. The possible role of the nicotinamide adenine nucleotides in the regulation of carbohydrate dissimilation is discussed.