title: A sugar-inducible protein kinase, VvSK1, regulates hexose transport and sugar accumulation in grapevine cells.
abstract: In grapevine (Vitis vinifera), as in many crops, soluble sugar content is a major component of yield and economical value. This paper identifies and characterizes a Glycogen Synthase Kinase3 protein kinase, cloned from a cDNA library of grape Cabernet Sauvignon berries harvested at the ripening stage. This gene, called VvSK1, was mainly expressed in flowers, berries, and roots. In the berries, it was strongly expressed at postvéraison, when the berries accumulate glucose, fructose, and abscisic acid. In grapevine cell suspensions, VvSK1 transcript abundance is increased by sugars and abscisic acid. In transgenic grapevine cells overexpressing VvSK1, the expression of four monosaccharide transporters (VvHT3, VvHT4, VvHT5, and VvHT6) was up-regulated, the rate of glucose uptake was increased 3- to 5-fold, and the amount of glucose and sucrose accumulation was more than doubled, while the starch amount was not affected. This work provides, to our knowledge, the first example of the control of sugar uptake and accumulation by a sugar-inducible protein kinase.
authors.affiliation: UMR Ecophysiology and Grape Functional Genomics, University of Bordeaux, INRA, Institut des Sciences de Vigne et du Vin, 33882 Villenave d'Ornon, France. fatma.lecourieux@bordeaux.inra.fr
authors.forename: Fatma
authors.initials: F
authors.lastname: Lecourieux
authors.forename: David
authors.initials: D
authors.lastname: Lecourieux
authors.forename: Céline
authors.initials: C
authors.lastname: Vignault
authors.forename: Serge
authors.initials: S
authors.lastname: Delrot
mesh_terms: D000595:Amino Acid Sequence; D005638:Fruit / Q000201:enzymology / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism*; D006601:Hexoses / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D016415:Sequence Alignment; D027843:Vitis / Q000201:enzymology* / Q000235:genetics
chemical_list: D006601:Hexoses; D010940:Plant Proteins; D018749:RNA, Plant; D038362:Glycogen Synthase Kinase 3