Planta

, Volume 207, Issue 4, pp 518–526

Photorespiratory metabolism of glyoxylate and formate in glycine-accumulating mutants of barley and Amaranthus edulis

  • Astrid Wingler
  • Peter J. Lea
  • Richard C. Leegood
Article

DOI: 10.1007/s004250050512

Cite this article as:
Wingler, A., Lea, P. & Leegood, R. Planta (1999) 207: 518. doi:10.1007/s004250050512

Abstract.

Glycine-accumulating mutants of barley (Hordeum vulgare L.) and Amaranthus edulis (Speg.), which lack the ability to decarboxylate glycine by glycine decarboxylase (GDC; EC 2.1.2.10), were used to study the significance of an alternative photorespiratory pathway of serine formation. In the normal photorespiratory pathway, 5,10-methylenetetrahydrofolate is formed in the reaction catalysed by GDC and transferred to serine by serine hydroxymethyltransferase. In an alternative pathway, glyoxylate could be decarboxylated to formate and formate could be converted into 5,10-methylenetetrahydrofolate in the C1-tetrahydrofolate synthase pathway. In contrast to wild-type plants, the mutants showed a light-dependent accumulation of glyoxylate and formate, which was suppressed by elevated (0.7%) CO2 concentrations. After growth in air, the activity and amount of 10-formyltetrahydrofolate synthetase (FTHF synthetase; EC 6.3.4.4), the first enzyme of the conversion of formate into 5,10-methylenetetrahydrofolate, were increased in the mutants compared to the wild types. A similar increase in FTHF synthetase could be induced by incubating leaves of wild-type plants with glycine under illumination, but not in the dark. Experiments with 14C showed that the barley mutants incorporated [14C]formate and [2-14C]glycollate into serine. Together, the accumulation of glyoxylate and formate under photorespiratory conditions, the increase in FTHF synthetase and the ability to utilise formate and glycollate for the formation of serine indicate that the mutants are able partially to compensate for the lack of GDC activity by bypassing the normal photorespiratory pathway.

Key words:Amaranthus (mutant)C1-tetrahydrofolate synthase pathway10-Formyltetrahydrofolate synthetaseGlycine decarboxylaseHordeum (mutant)Photorespiration

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Astrid Wingler
    • 1
  • Peter J. Lea
    • 2
  • Richard C. Leegood
    • 1
  1. 1.Robert Hill Institute and Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UKGB
  2. 2.Biological Sciences, Lancaster University, Lancaster, LA1 4YQ, UKGB