Abstract
15N-labelled (amino group) asparagine (Asn), glutamate (Glu), alanine (Ala), aspartate (Asp) and serine (Ser) were used to study the metabolic role and the participation of each compound in the photorespiratory N cycle ofPisum sativum L. leaves. Asparagine was utilised as a nitrogen source by either deamidation or transamination, Glu was converted to Gln through NH3 assimilation and was a major amino donor for transamination, and Ala was utilised by transamination to a range of amino acids. Transamination also provided a pathway for Asp utilisation, although Asp was also used as a substrate for Asn synthesis. In the photorespiratory synthesis of glycine (Gly), Ser, Ala, Glu and Asn acted as sources of amino-N, contributing, in the order given, 38, 28, 23, and 7% of the N for glycine synthesis; Asp provided less than 4% of the amino-N in glycine. Calculations based on the incorporation of15N into Gly indicated that about 60% (Ser), 20% (Ala), 12% (Glu) and 11% (Asn) of the N metabolised from each amino acid was utilised in the photorespiratory nitrogen cycle.
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Abbreviations
- Ala:
-
alamine
- Asn:
-
asparagine
- Asp:
-
aspartate
- Glu:
-
glutamate
- MOA:
-
methoxylamine
- Ser:
-
serine
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Ta, T.C., Joy, K.W. Metabolism of some amino acids in relation to the photorespiratory nitrogen cycle of pea leaves. Planta 169, 117–122 (1986). https://doi.org/10.1007/BF01369782
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DOI: https://doi.org/10.1007/BF01369782