THE REGULATION AND CONTROL OF PHOTORESPIRATION

The photorespiratory pathway is described, together with the mutants which have been isolated for this metabolic pathway, Some of the key regulatory properties of the photorespiratory cycle are reviewed together with the regulatory interactions that might occur between photorespiration and other processes, such as the Benson-Calvin cycle and anaplerotic carbon flow into organic acids, These are discussed in relation to recent studies of the regulation and control of photorespiratory carbon and nitrogen metabolism in photorespiratory mutants, including possible mechanisms for the control of photosynthetic and photorespiratory carbon and nitrogen metabolism and of the activation state of ribulose-1,5-bisphosphate carboxylase/oxygenase in heterozygous barley mutants with reduced activities of glutamine synthetase or glutamate synthase.