Utilization of Labeled Glucose in Developing Douglas Fir Seed Cones

Abstract

The utilization of glucose by developing Douglas fir cones during the stages of 75-105 days after pollination was studied by incubating radioactive glucose with cone scale and seed for 6 hours in a respirometer. The distribution of radioactivity was determined in respiratory CO2, hot ethyl alcohol extract, iso-octane extract, and insoluble residue of both tissues. The adsorption of radioactive glucose decreased with development stage, and there was no difference in total adsorption of glucose-1-C14 and glucose-6-C14. Seed adsorbed 4 times as much as the scale in early developmental stages, then declined to 2-fold at the last stage of the experiment. Synthesis of fat and cellular components from labeled glucose was demonstrated, and the rate of fat synthesis increased with maturity in seed. A preferential utilization of carbon-1 for respiration and carbon-6 for synthesis was indicated by the differential radioactivity found in various fractions. The respiration of the developing organs was determined by manometric technique, and it was found that the respiratory rate decreased with maturity and that seed respired more than cone scale. The correlation of respiration and metabolic activities was well demonstrated in the material.