JXB Advance Access originally published online on September 10, 2004
Journal of Experimental Botany 2004 55(406):2179-2189; doi:10.1093/jxb/erh235
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RESEARCH PAPER |
Methyl-ß-D-glucopyranoside in higher plants: accumulation and intracellular localization in Geum montanum L. leaves and in model systems studied by 13C nuclear magnetic resonance




1Station Alpine du Lautaret, Université Joseph Fourier, BP 53, F-38041 Grenoble cedex 9, France
2Laboratoire de Physiologie Cellulaire Végétale, UMR 5168 CNRS-INRA-UJF-CEA, DRDC, Commissariat à l'Energie Atomique, 17 rue des Martyrs, F-38054 Grenoble cedex 9, France
* To whom correspondence should be addressed at Laboratoire d'Ecologie Alpine, Université Joseph Fourier, BP 53, F-38041 Grenoble cedex 9, France. Fax: +33 (0)4 76 51 42 79. E-mail: serge.aubert{at}ujf-grenoble.fr
Using 13C-NMR, methyl-ß-D-glucopyranoside (MeG) was characterized as a major compound in the leaves of the alpine herb Geum montanum L. MeG continuously accumulated during the life span of G. montanum leaves, and accounted for up to 20% of the soluble carbohydrates in aged overwintering leaves, without being reallocated during senescence. Incubating intact plant tissues, culture cells, and purified organelles with 13C-labelled substrates showed that MeG was synthesized in the cytosol of cells, directly from glucose and methanol molecules. There was no contribution of the C-1 pathway. MeG was subsequently stored in the vacuole without being re-exported to the cytoplasm. All the dicots tested contained the enzymatic machinery permitting MeG synthesis from methanol and glucose, but the plants accumulating this compound at concentrations higher than 1 µmol g1 wet wt were mainly members of the Rosaceae family belonging to the Rosoideae subfamily. It is suggested that the synthesis of MeG may contribute to reduce the accumulation in the cytoplasm of methanol and its derived compounds.
Key words: Geum montanum, leaf life span, methyl-ß-D-glucopyranoside, NMR spectroscopy, pathway compartmentation, taxonomic distribution