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Nitrogen Mobilization in Pea Seedlings. II. Free Amino Acids

1963; Oxford University Press; Volume: 38; Issue: 5 Linguagem: Inglês

10.1104/pp.38.5.561

1532-2548

Jean M. Lawrence, D.R. Grant,

Plant nutrient uptake and metabolism

In an earlier report from this laboratory (10) the changes in protein nitrogen and various forms of nonprotein nitrogen-amino, amide, peptide, am- monia, and urea-were reported for the different tis- sues of peas and pea seedlings during the early stages of growth.The data emphasize the quantitative importance of the free amino acids, particularly in the roots and shoots of these young seedlings.Although they contribute only about 3 % to the total nitrogen of the seed, their contribution rises to 10 % in the 5-day seedling.In root shaft and shoot shaft tissue of the 5-day seedling, from 40 to 45 % of the nitrogen is in the free amino acids.The work did not make clear the role these amino acids plav in the conversion of the storage proteins of the seed to the functional proteins of the young plant.Clearly the first information needed for this purpose is a dcetailed picture of the changes in the concentration of the in- dividual amino acids.The cotyledons and embryonic axis tissue of pea seeds before and after one day's germination, and the cotyledons, root shafts, shoot shafts, root tips, and shoot tips of 3-and 5-day seedlings have been ana- lyzed for their free amino acid content.The results give evidence for extensive interconversions and me- tabolism of amino acids during seedling growth, and show much similarity between the compositions of seedling root and shoot tissue.The very high levels of homoserine in certain tissues are documented.