METABOLIC-REGULATION IN PLANT-CELL CULTURE .43. LEVELS OF METABOLITES RELATED TO GLYCOLYSIS IN CATHARANTHUS-ROSEUS CELLS DURING CULTURE

The rate of respiration and levels of various compounds that are involved in the metabolism of carbohydrate were determined in suspension-cultured Catharanthus roseus cells that were subcultured at 10-day intervals. Maximum rates of uptake of O-2 were found during the lag phase (day 1) and the logarithmic phase (days 4-5). The levels of sucrose, starch and hexose phosphates increased during the first four to six days after inoculation. A decrease in levels of sucrose was detected earlier than in that of starch. The pools of triose phosphates were smaller than those of hexose phosphates during the entire culture period. The level of phosphoenolpyruvate was low when maximum respiratory rates were recorded. By contrast, the accumulation of pyruvate was observed transiently when the rate of respiration began to decrease. The level of ATP increased during first one-day period after transfer of cells to fresh medium and then it decreased. The adenylate energy charge was almost constant (0.76-0.78), apart from an initial increase on day 1 (to 0.85). The level of PPi remained high during the logarithmic phase of growth. These results are discussed in the context of possible mechanisms for the regulation of the metabolism of carbohydrates, and of glycolysis in particular, in cells at different stages of culture.