Arabidopsis glt1-T mutant defines a role for NADH-GOGAT in the non-photorespiratory ammonium assimilatory pathway

Muriel Lancien, Melinda Martin, Ming Hsiun Hsieh, Tom Leustek, Howard Goodman, Gloria M. Coruzzi

Research output: Contribution to journalArticlepeer-review


The physiological role of the NADH-dependent glutamine-2-oxoglutarate aminotransferase (NADH-GOGAT) enzyme was addressed in Arabidopsis using gene expression analysis and by the characterization of a knock-out T-DNA insertion mutant (glt1-T) in the single NADH-GOGAT GLT1 gene. The NADH-GOGAT GLT1 mRNA is expressed at higher levels in roots than in leaves. This expression pattern contrasts with GLU1, the major gene encoding Fd-GOGAT, which is most highly expressed in leaves and is involved in photorespiration. These distinct organ-specific expression patterns suggested a non-redundant physiological role for the NADH-GOGAT and Fd-GOGAT gene products. To test the in vivo function of NADH-GOGAT, we conducted molecular and physiological analysis of the glt1-T mutant, which is null for NADH-GOGAT, as judged by mRNA level and enzyme activity. Metabolic analysis showed that the glt1-T mutant has a specific defect in growth and glutamate biosynthesis when photorespiration was repressed by 1% CO2. Under these conditions, the glt1-T mutant displayed a 20% decrease in growth and a dramatic 70% reduction in glutamate levels. Herein, we discuss the significance of NADH-GOGAT in non-photorespiratory ammonium assimilation and in glutamate synthesis required for plant development.

Original languageEnglish (US)
Pages (from-to)347-358
Number of pages12
JournalPlant Journal
Issue number3
StatePublished - 2002


  • Glutamate
  • Glutamine
  • Photorespiration

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology


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