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Glutamine in sugar beet: Where is it synthesized?

  • Autor/in: Mäck, G.
  • Jahr: 2003
  • Zeitschrift: Proc. 1. joint IIRB-ASSBT-Congress
  • Verlag: San Antonio
  • Seite/n: 925-929


Glutamine is the predominant amide in the beet. It is assumed that it is produced in the leaves and translocated to the beet (Burba et al., 1984). The aim of the present study was to evaluate the contribution of the different plant organs in synthesis and accumulation of glutamine when either nitrate (NO3-, 5 mM) or ammonium (NH4+, 5 mM) is supplied as N source. The plants were grown hydroponically under controlled conditions for 40 days. The results indicate that glutamine in the beet is imported via xylem and phloem from various organs, not only from leaf blades. Furthermore, it is snythesized in the beet (crown and root) itself. The contribution in glutamine synthesis of the different organs changes with the N source of the plant. Synthesis of glutamine accumulating in the beet is catalyzed by both the chloroplastic and cytosolic isoenzymes of glutamine synthetase.
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