Effect of Fluoride on Glucose Catabolism in Plant Leaves

Abstract

The influence of fluoride injury on O2 absorption and carbon dioxide release from glucose-1-C14, glucose-6-C14, and glucose-2-C14 was studied in leaves of Polygonum orientale and Chenopodium murale. Leaf discs were taken from plants fumigated with HF or from excised leaves exposed to KF solution and were incubated in Warburg vessels. Release of C14O2 from glucose-6-C14 was compared to that of glucose-1-C14 (C6/C1 ratios) and to glucose-2-C14 (C6/C2 ratios) to estimate the pathways of glucose breakdown. In injured leaves increases in O2 uptake and C14O2 release often occurred. Both fluoride treatment methods caused decreased C6/C1 ratios, suggesting a relative increase in importance of the pentose phosphate pathway. C6/C2 ratios were consistently less than 1 in all tissues, which would be expected if glucose were catabolized by the glycolytic and pentose phosphate pathways.