Increased activity of the vacuolar monosaccharide transporter TMT1 alters cellular sugar partitioning, sugar signaling, and seed yield in Arabidopsis
| Autor: | H. Ekkehard Neuhaus, Rainer Hedrich, Oliver Trentmann, Stefan Wic, Arnd G. Heyer, Alexander Schulz, Irene Marten, Karina Wingenter, Alexandra Wormit, Imke I. Hoermiller |
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| Rok vydání: | 2010 |
| Předmět: |
Sucrose
Patch-Clamp Techniques Monosaccharide Transport Proteins Physiology Mutant Molecular Sequence Data Arabidopsis Biochemical Processes and Macromolecular Structures Plant Science Vacuole chemistry.chemical_compound Gene Expression Regulation Plant Genetics Monosaccharide Arabidopsis thaliana Photosynthesis Sugar Plant Proteins chemistry.chemical_classification biology Arabidopsis Proteins Plant physiology food and beverages Membrane Transport Proteins Biological Transport biology.organism_classification Plants Genetically Modified chemistry Biochemistry Mutation Seeds Vacuoles Carbohydrate Metabolism |
| Zdroj: | Plant physiology. 154(2) |
| ISSN: | 1532-2548 |
| Popis: | The extent to which vacuolar sugar transport activity affects molecular, cellular, and developmental processes in Arabidopsis (Arabidopsis thaliana) is unknown. Electrophysiological analysis revealed that overexpression of the tonoplast monosaccharide transporter TMT1 in a tmt1-2::tDNA mutant led to increased proton-coupled monosaccharide import into isolated mesophyll vacuoles in comparison with wild-type vacuoles. TMT1 overexpressor mutants grew faster than wild-type plants on soil and in high-glucose (Glc)-containing liquid medium. These effects were correlated with increased vacuolar monosaccharide compartmentation, as revealed by nonaqueous fractionation and by chlorophyllab-binding protein1 and nitrate reductase1 gene expression studies. Soil-grown TMT1 overexpressor plants respired less Glc than wild-type plants and only about half the amount of Glc respired by tmt1-2::tDNA mutants. In sum, these data show that TMT activity in wild-type plants limits vacuolar monosaccharide loading. Remarkably, TMT1 overexpressor mutants produced larger seeds and greater total seed yield, which was associated with increased lipid and protein content. These changes in seed properties were correlated with slightly decreased nocturnal CO2 release and increased sugar export rates from detached source leaves. The SUC2 gene, which codes for a sucrose transporter that may be critical for phloem loading in leaves, has been identified as Glc repressed. Thus, the observation that SUC2 mRNA increased slightly in TMT1 overexpressor leaves, characterized by lowered cytosolic Glc levels than wild-type leaves, provided further evidence of a stimulated source capacity. In summary, increased TMT activity in Arabidopsis induced modified subcellular sugar compartmentation, altered cellular sugar sensing, affected assimilate allocation, increased the biomass of Arabidopsis seeds, and accelerated early plant development. |
| Databáze: | OpenAIRE |
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