The Direct Oxidation Pathway in Plant Respiration.

Abstract
Experiments were carried out on a variety of plant tissues to find whether the oxidative pathway of glucose breakdown ("hexosemonophosphate shunt") contributes to their respiration. When initial yields of C14O2 from equal amounts of glucose-l-Cl4 and glucose-6-Cl4 were compared there was clear evidence that, in most of the tissues, some of the glucose was, in fact, broken down in reactions in which C-l was split off at an earlier stage than C-6. It has been calculated from the data that in several of the tissues a maximum of about half of the glucose was broken down by the E.M.P. pathway. The fact that the initial yields of C14O2 from the two kinds of glucose were the same when corn root tips were used confirms an earlier finding that in this juvenile tissue the classical glycolytic route is the sole one; in the other tissues it is concluded that a substantial fraction of the glucose is respired via the direct oxidation pathway.