NUTRITIVE ROLE OF THE SEEDCOATS DURING EMBRYO DEVELOPMENT IN PISUM-SATIVUM-L

Structural and metabolic features of the seedcoats of the developing pea seed [cv. Telephone] indicate that events in the cells of the seedcoats are of major importance in controlling the development of the embryo. Information has been obtained on the distribution of N and P constituents of the seedcoats, embryo sac liquid, and the cotyledons of the embryo, in relation to the changes in the activities of several enzymes: aminopeptidases, .beta.-glucosidase and acid phosphatase. The liquid contents of the embryo sac are considered to arise as a secretion from the tegmen. High concentrations of amino acids (about 0.3 M), NH4+ (about 0.1 molar), and orthophosphate (Pi) (up to 4 mM) were measured in this fluid. Since Pi was the only form of P present, the data confirm the possible function of some of the seedcoat acid phosphatase activity in the provision of Pi to the embryo.