Amino Acid leakage from cotyledons of developing and germinating pea seeds

The leakage of amino acids from cotyledons of developing pea seeds into a bathing medium was relatively high at an early stage of development but low at later stages. Depending on the stage of development, the leakage was influenced differently by the sulfhydrylgroup modifier, PCMBS, and the metabolic uncoupler, CCCP. No prolonged leakage was measured from detached cotyledons and cotyledon discs after five days of germination. The composition of the amino acid fraction released by developing cotyledons differed from the amino acid pool of the cotyledons. Particularly alanine and also serine, glycine and γ-aminobutyric acid were released whereas glutamine and arginine showed a relatively low leakage. The amino acid fraction which normally enters the free space between the seedcoat and the embryo contained relatively large amounts of both alanine and glutamine. Results of the leakage experiments are discussed in relation to the sink-source transition of the storage parenchyma cells.