Abstract
The translccation of radioactive photosynthetic assimilates in mulberry plant after assimilation of 14CO2 was followed. Plants were first placed in 14CO2 containing air for two hours, then photosynthesis was allowed to continue in 14CO2 air for varying periods up to 10 hours. Radio-activities in various parts of the plant at 2, 6 and 10 hours after 14CO2 assimilation were determined. The gross radioactivities in each part of plant decreased in the order of leaf, stembark, stump bark, stem wood, stump bark or root at the end of 14CO2 assimilation and two hours later. Plant parts other than leaf and stem bark continued to accumulate the radioactive assimilates during 10 hours of the experimental period.
Among fractions of the radioactive photosynthates, sugar raction contained the bulk of the radioactivity in any plant parts. The radioactivities of sucrose in the leaf and the stem bark accounted for 40% of the gross radioactivities of respective tissues at the end of 14CO2 assimilation. During two hours following the 14CO2 assimilation period the specific radioactivity of sucrose in the stem bark rose to almost three times and then slowly fell to the level as before. These may suggest that the radioactivity assimilated is translocated predominantly in the form of sucrose in the stem bark.
In the amino acids fraction the labelings were mostly present in alanine and serine in the leaves, while in asparagine and glutamine in the roots.
