title: Characterization of a grapevine R2R3-MYB transcription factor that regulates the phenylpropanoid pathway.
abstract: The ripening of grape (Vitis vinifera) berry is characterized by dramatic changes in gene expression, enzymatic activities, and metabolism that lead to the production of compounds essential for berry quality. The phenylpropanoid metabolic pathway is one of the components involved in these changes. In this study, we describe the cloning and functional characterization of VvMYB5a, a cDNA isolated from a grape L. cv Cabernet Sauvignon berry library. VvMYB5a encodes a protein belonging to a small subfamily of R2R3-MYB transcription factors. Expression studies in grapevine indicate that the VvMYB5a gene is mainly expressed during the early steps of berry development in skin, flesh, and seeds. Overexpression of VvMYB5a in tobacco (Nicotiana tabacum) affects the expression of structural genes controlling the synthesis of phenylpropanoid and impacts on the metabolism of anthocyanins, flavonols, tannins, and lignins. Overexpressing VvMYB5a induces a strong accumulation of several phenolic compounds, including keracyanin (cyanidin-3-rhamnoglucoside) and quercetin-3-rhamnoglucoside, which are the main anthocyanin and flavonol compounds in tobacco. In addition, VvMYB5a overexpression increases the biosynthesis of condensed tannins and alters lignin metabolism. These findings suggest that VvMYB5a may be involved in the control of different branches of the phenylpropanoid pathway in grapevine.
authors.affiliation: Unité Mixte de Recherche 619, Physiologie et Biotechnologie Végétales, Université Bordeaux 1, Université Bordeaux 2, Institut National de la Recherche Agonomique, Centre de Recherche de Bordeaux, 33883 Villenave d'Ornon, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Deluc
authors.forename: François
authors.initials: F
authors.lastname: Barrieu
authors.forename: Chloé
authors.initials: C
authors.lastname: Marchive
authors.forename: Virginie
authors.initials: V
authors.lastname: Lauvergeat
authors.forename: Alain
authors.initials: A
authors.lastname: Decendit
authors.forename: Tristan
authors.initials: T
authors.lastname: Richard
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Carde
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Mérillon
authors.forename: Saïd
authors.initials: S
authors.lastname: Hamdi
mesh_terms: D002392:Catechin / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D005419:Flavonoids / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism; D020598:Proto-Oncogene Proteins c-myb / Q000502:physiology*; D014026:Nicotiana / Q000235:genetics; D027843:Vitis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005419:Flavonoids; D010940:Plant Proteins; D020598:Proto-Oncogene Proteins c-myb; D002392:Catechin