Phosphorus Metabolism of Germinating Oat Seeds

An investigation has been made of the changes in the major phosphorus containing substances in Avena sativa during the first 8 days of dark germination. The endosperm, roots, and shoots were analyzed separately for acid soluble-P, phytic acid-P, inorganic-P, lipid-P, nucleic acid-P, and protein-P. Phytic acid-P comprised 53% of the total seed phosphate, while the sum of lipid-P, nucleic acid-P and protein-P comprised 27% of the seed phosphate. All these reserve phosphate materials were mobilized and transferred to the developing axis. The phosphate from phytic acid appeared almost entirely as inorganic-P in the roots and shoots. A close stoichiometry existed between the rate of loss of nucleic acid-P from the endosperm and its rate of appearance in the roots and shoots. Thus no net synthesis of nucleic acid occurred during the 8-day period examined. The rate of synthesis of lipid-P in the roots and shoots exceeded its rate of disappearance from the endosperm during the first 4 days of germination. Protein-P increased in the roots and shoots during germination, but at a rate less than its rate of disappearance from the endosperm. The results provide a relatively complete description of the over-all aspects of phosphorus metabolism associated with germination of oats.