Chlorophyll Accumulation, CO2 Fixation Enzymes, and Hill Activity, in Greening Roots of Lens culinaris

The carboxylation of ribulose‐1,5‐diphosphate was demonstrated in vitro with extracts of ctiolated seedling roots. The presence of ribulose‐1,5‐diphosphate carboxylase was characterized in the subcellular fraction enriched in amyloplasts. Synthesis of chlorophyll, development of CO2 fixation capacities and of Hill activity upon illumination have been studied with roots of Lens culinaris seedlings. The marked increases in CO2 fixation with ribulose‐1,5‐diphosphate as the substrate and in Hill activity that occur after a lag phase seem to be related to cytological changes during the greening of roots.