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Apparent coordination of isocitrate dehydrogenase and glutamate decarboxylase expression in early stages of tree development

The biosynthesis of 2-oxoglutarate and glutamate are key steps in the biosynthesis of nitrogen compounds and plant development. The reaction catalyzed by cytosolic isoenzyme of NADP+-linked isocitrate dehydrogenase (IDH) is also considered as the main route in the production of 2-oxoglutarate. According to its expression pattern during development, IDH is also involved in other, yet unknown, processes [1, 2]. In addition to the importance of glutamate in the biosynthesis of nitrogen compounds, glutamate also serves as precursor of GABA, a molecule that is currently considered as a signal in higher plants. GABA is produced by the action of glutamate decarboxylase (GAD), a cytosolic enzyme that is regulated by Ca2+/calmodulin and pH. In contrast to IDH, that it is encoded by just one gene in most of plant genomes [2], GAD is encoded by a small family of nuclear genes [3]. The expression of IDH and GAD has been investigated during the differentiation of hypocotyl and stem in tree species. Our results indicate a coordination of the expression of IDH and GAD in developmental processes suggesting a role for 2-oxoglutarate supply and GABA synthesis during early stages of organ differentiation in trees.

References

  1. 1.

    Palomo J, Gallardo F, Suárez MF, Cánovas C: Purification and characterization of NADP+-linked isocitrate dehydrogenase from Scots pine. Plant Physiol. 1998, 118: 617-626. 10.1104/pp.118.2.617.

  2. 2.

    Pascual MB, Molina-Rueda JJ, Cánovas FM, Gallardo F: Spatial distribution of cytosolic NADP+-isocitrate dehydrogenase in pine embryos and seedlings. Tree Physiol. 2008, 28: 1773-1782.

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    Molina-Rueda JJ, Pascual MB, Cánovas FM, Gallardo F: Characterization and developmental expression of a glutamate decarboxylase from maritime pine. Planta. 2010, 232: 1471-1483. 10.1007/s00425-010-1268-9.

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Correspondence to Fernando Gallardo.

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Keywords

  • Nitrogen
  • Glutamate
  • Tree Species
  • Developmental Process
  • Plant Development