Release of amino acids from cotyledons of developing seeds of pea (pisum sativum L.)

Summary The release of amino acids from isolated cotyledons of developing pea seeds into a bathing medium was studied. The amount released depended on the developmental stage of the cotyledons. The release from cotyledons at an early stage was twenty times more than the amount released by cotyledons at a later stage. As a proportion of the internal pool of free amino acids, the release at early developmental stages was 23 % whereas at later stages it was 7 % of this pool. Evidence is presented suggesting that the release originates from both an apoplastic source and from at least one of the symplastic pools. Resorption of the released amino acids started after 5 to 6 h of incubation; this is probably related to the incorporation of amino acids into protein. Arguments are put forward, suggesting that the resorption is mediated by a saturable and a non-saturable uptake system.