<P> Although the functions of photorespiration remain controversial, it is widely accepted that this pathway influences a wide range of processes from bioenergetics, photosystem II function, and carbon metabolism to nitrogen assimilation and respiration . The photorespiratory pathway is a major source of hydrogen peroxide (H 2O 2) in photosynthetic cells . Through H 2O 2 production and pyridine nucleotide interactions, photorespiration makes a key contribution to cellular redox homeostasis . In so doing, it influences multiple signalling pathways, in particular, those that govern plant hormonal responses controlling growth, environmental and defense responses, and programmed cell death . </P> <P> Another theory postulates that it may function as a "safety valve", preventing the excess of reductive potential coming from an overreduced NADPH - pool from reacting with oxygen and producing free radicals, as these can damage the metabolic functions of the cell by subsequent oxidation of membrane lipids, proteins or nucleotides . </P>

G3p is a useful product for green plants because it