title: Sugar-regulated expression of a putative hexose transport gene in grape.
abstract: Different lengths of the promoter of grape (Vitis vinifera) VvHT1 (Hexose Transporter 1) gene, which encodes a putative hexose transporter expressed during the ripening of grape, have been transcriptionally fused to the beta-glucuronidase reporter gene. In transgenic tobacco (Nicotiana tabacum) transformed with these constructs, VvHT1 promoters were clearly responsible for the sink organ preferential expression. The potential sugar effectors of VvHT1 promoter were studied in tobacco cv Bright-Yellow 2 cells transformed with chimeric constructs. Glucose (56 mM), sucrose (Suc; 58 mM), and the non-transported Suc isomer palatinose doubled the beta-glucuronidase activity conferred by the VvHT1 promoter, whereas fructose did not affect it. These effects were the strongest with the 2.4-kb promoter, which contains all putative sugar-responsive elements (activating and repressing), but they were also significant with the 0.3-kb promoter, which contains only activating sugar boxes. The induction of VvHT1 expression by both Suc and palatinose was confirmed in the homologous grape berry cell culture. The data provide the first example of a putative sugar transporter, which is induced by both glucose and Suc in higher plants. Although induction of VvHT1 expression by Suc does not require transport, the presence of glucosyl moiety is necessary for Suc sensing. These results provide new insights into sugar sensing and signaling in plants.
authors.affiliation: Unité Mixte de Recherche-Centre National de la Recherche Scientifique 6161, Transport des Assimilats, Laboratoire de Physiologie, Biochimie et Biologie Moléculaires Végétales, Poitiers, France. Rossitza.Atanassova@univ-poitiers.fr
authors.forename: Rossitza
authors.initials: R
authors.lastname: Atanassova
authors.forename: Marina
authors.initials: M
authors.lastname: Leterrier
authors.forename: Cécile
authors.initials: C
authors.lastname: Gaillard
authors.forename: Alice
authors.initials: A
authors.lastname: Agasse
authors.forename: Emeric
authors.initials: E
authors.lastname: Sagot
authors.forename: Pierre
authors.initials: P
authors.lastname: Coutos-Thévenot
authors.forename: Serge
authors.initials: S
authors.lastname: Delrot
mesh_terms: D002241:Carbohydrates / Q000494:pharmacology*; D002478:Cells, Cultured; D005632:Fructose / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D005966:Glucuronidase / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D007534:Isomaltose / Q000031:analogs & derivatives* / Q000494:pharmacology; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology; D014026:Nicotiana / Q000166:cytology; D027843:Vitis / Q000166:cytology / Q000235:genetics*
chemical_list: D002241:Carbohydrates; D009004:Monosaccharide Transport Proteins; D011993:Recombinant Fusion Proteins; D005632:Fructose; D013395:Sucrose; D007534:Isomaltose; D005966:Glucuronidase; D005947:Glucose; C008189:isomaltulose