title: Overexpression of a proton-coupled vacuolar glucose exporter impairs freezing tolerance and seed germination.
abstract: Arabidopsis vacuoles harbor, besides sugar transporter of the TMT-type, an early response to dehydration like 6 (ERDL6) protein involved in glucose export into the cytosol. However, the mode of transport of ERDL6 and the plant's feedback to overexpression of its activity on essential properties such as, for example, seed germination or freezing tolerance, remain unexplored. Using patch-clamp studies on vacuoles expressing AtERDL6 we demonstrated directly that this carrier operates as a proton-driven glucose exporter. Overexpression of BvIMP, the closest sugar beet (Beta vulgaris) homolog to AtERDL6, in Arabidopsis leads surprisingly to impaired seed germination under both conditions, sugar application and low environmental temperatures, but not under standard conditions. Upon cold treatment, BvIMP overexpressor plants accumulated lower quantities of monosaccharides than the wild-type, a response in line with the reduced frost tolerance of the transgenic Arabidopsis plants, and the fact that cold temperatures inhibits BvIMP transcription in sugar beet leaves. With these findings we show that the tight control of vacuolar sugar import and export is a key requisite for cold tolerance and seed germination of plants.
authors: Plant Physiology, University of Kaiserslautern, Erwin-Schrödinger-Str., D-67653, Kaiserslautern, Germany.
authors: Patrick A W
authors: PAW
authors: Klemens
authors: Plant Physiology, University of Kaiserslautern, Erwin-Schrödinger-Str., D-67653, Kaiserslautern, Germany.
authors: Kathrin
authors: K
authors: Patzke
authors: Plant Physiology, University of Kaiserslautern, Erwin-Schrödinger-Str., D-67653, Kaiserslautern, Germany.
authors: Oliver
authors: O
authors: Trentmann
authors: Centre for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 360, 69120, Heidelberg, Germany.
authors: Gernot
authors: G
authors: Poschet
authors: Centre for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 360, 69120, Heidelberg, Germany.
authors: Michael
authors: M
authors: Büttner
authors: Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany.
authors: Alexander
authors: A
authors: Schulz
authors: Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany.
authors: Irene
authors: I
authors: Marten
authors: Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, D-97082, Würzburg, Germany.
authors: Rainer
authors: R
authors: Hedrich
authors: Plant Physiology, University of Kaiserslautern, Erwin-Schrödinger-Str., D-67653, Kaiserslautern, Germany.
authors: H Ekkehard
authors: HE
authors: Neuhaus
mesh_terms: D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D027461:Beta vulgaris; D055162:Biocatalysis; D001692:Biological Transport; D050260:Carbohydrate Metabolism; D004553:Electric Conductivity; D005615:Freezing; D018506:Gene Expression Regulation, Plant; D018525:Germination; D005947:Glucose / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes / Q000235:genetics / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011522:Protons; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000254:growth & development*; D015398:Signal Transduction; D013213:Starch / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C490217:CAB1 protein, Arabidopsis; D045342:Light-Harvesting Protein Complexes; D009004:Monosaccharide Transport Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D011522:Protons; D012333:RNA, Messenger; D013213:Starch; D005947:Glucose
keywords: Arabidopsis; glucose transport; stress tolerance; tonoplast; vacuole