The study of hydrogen isotopic fractionations during its incorporation into plant biomass may have important applications in plant biochemistry, physiology, physiological ecology and several other fields. Of particular interest in this proposal is the deuterium enrichment observed in non-exchangeable hydrogens of cellulose from CAM plants. Evidence is presented showing that biochemical reactions are responsible for this deuterium enrichment. The objective of the experiments outlined in this proposal is to determine which metabolic pathway is responsible for deuterium enrichment in CAM plants. Whole plant and tissue culture experiments are proposed here. The results of these experiments will determine whether deuterium enrichment can occur during the glycolysis-gluconeogenesis cycle found in CAM plants. An increased knowledge of the processes responsible for deuterium enrichment in CAM plants will be significant in the study of carbohydrate pools and source sink relations. More broadly, the results of this study will have important applications in the study of photosynthetic systems in relation to environmental parameters.
