Study of the expression of the GDU1-related genes in Arabidopsis
Final Report Abstract
Transport of solutes across membranes plays a major role in plant cell biology. It is mediated by dedicated membrane proteins that are involved in either transport towards the cytosol (import) or out from the cytosol (export), e.g. apoplasm, vacuole, organelles. Many gene families involved in import of numerous substances (e.g. sugars, amino acids, inorganic anions and cations, organic acids) have been identified and characterized in Arabidopsis. Genes involved in export are far less characterized although export is as much important for the plant as import. The gdu1-1D mutant has been isolated that presented secretion of glutamine at the hydathodes. Characterization of the phenotype of the plants suggested that amino acid metabolism and transport are disturbed by the over-expression of Glutamine Dumper 1 (GDU1). The present work aimed at characterizing the function of the six GDU1- like genes in Arabidopsis. Localization of the expression using promoter-GUS fusions, and quantitative RT-PCR showed that these genes are mostly expressed in vascular tissues of roots and stems. The over-expression of the GDU genes led to mutants reminiscent of gdu1- 1D: smaller plants, over-accumulating free amino acids and tolerant to exogenously applied amino acids. Radio-labeled amino acid accumulation showed that amino acid uptake is reduced in GDU over-expressing plantlets. Furthermore, accumulation kinetics suggested that import capacity is unchanged but that export is stimulated. This study shows that the GDU genes are endowed with similar functional properties that affect amino acid export.
Publications
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Pratelli, R., and Pilot, G. (2007). Corrigendum to "The plant-specific VIMAG domain of Glutamine Dumper1 is necessary for the function of the protein in arabidopsis" [FEBS Lett. 580 (2006) 6961-6966]. FEBS lett. 581, 1248-1249.
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Pratelli, R., and Pilot, G. (2006). The plant-specific VIMAG domain of Glutamine Dumper1 is necessary for the function of the protein in arabidopsis. FEBS lett. 580, 6961- 6966.
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Pratelli, R., and Pilot, G. (2007). Altered amino acid metabolism in glutamine dumper1 plants. Plant Signal. & Behav. 2, 171-173.
