Respiratory Mechanisms and the Changes of Glutathione and Ascorbic Acid in Germinating Peas

Abstract

The respiration of pea seeds during the early stages of germination was studied by manometric methods. From analyses of the germinating seeds estimates were obtained of the oxidized and reduced forms of glutathione and ascorbic acid. Thus it was possible to explore the relationship between these oxidation-reduction systems and the resumption of respiratory activities in the dormant seed. Several lines of evidence indicate that partial anaerobiosis is an important feature of metabolism during the first phases of germination in air. The intact testa, acting as a barrier to diffusion, limits the uptake of oxygen by the seed. Splitting of the testa by the development of the embryo leads to rapid changes in the mechanism and rate of respiration. An increase in the relative proportions of the reduced forms of both glutathione and ascorbic acid is associated with the establishment of anaerobic conditions in the seed. This and other available evidence indicate that the glutathione-ascorbic acid carrier system plays only a minor part in aerobic oxidations during the early stages of germination. The possibility that glutathione has an important influence on the activation of enzymes in the first phase of germination is briefly considered.