Ecological Significance of the Interaction of Photosynthesis Light and Dark Processes

Abstract

The kinetics of 14C incorporation into glycolate was studied after changing the export of photosynthetic products from the leaf. It has been shown that the ribulose-bisphosphate-oxygenase pathway of glycolate formation works in the stationary state of the plant. An excess of photosyntates or a decrease in the amount of light primary products, as well as nitrates in the leaves, immediately turns on the transketolase pathway of glycolate formation. In this case, part of the oxygen formed in the photochemical reactions of chloroplasts ceases to be released from the leaf. After oxygen receives an electron from ferredoxin in the electron transport chain of chloroplasts, it starts (through photorespiration) the formation of non-carbohydrate photosyntates and metabolic processes in the cytoplasm. It was concluded that the main function of photorespiration in the regulation of photosynthesis is maintaining a balance between light and dark processes of photosynthesis on change of living conditions.