New member of the R2R3-MYB transcription factors family in grapevine suppresses the anthocyanin accumulation in the flowers of transgenic tobacco.
In grapevine, anthocyanins and proanthocyanidins are the main flavonoids in berries, which are associated to organoleptic properties in red wine such as color and astringency. Flavonoid pathway is specifically regulated at transcriptional level and several R2R3-MYB proteins have shown to act as positive regulators. However, some members of this family have shown to repress the flavonoid biosynthesis. In this work, we present the characterization of VvMYB4-like gene, which encodes a putative transcriptional factor highly expressed in the skin of berries at the pre veraison stage in grapevine. Its over-expression in tobacco resulted in the loss of pigmentation in flowers due a decrease in anthocyanin accumulation. Severity in anthocyanin suppression observed in petals could be associated with the expression level of the VvMYB4-like transgene. Expression analysis of flavonoid structural genes revealed the strong down-regulation of the flavonoid-related genes anthocyanidin synthase (ANS) and dihydroflavonol reductase (DFR) genes and also the reduction of the anthocyanin-related gene UDP glucose:flavonoid 3-O-glucosyl transferase (UFGT), which was dependent of the transgene expression. In addition, expression of VvMYB4-like in the model plant Arabidopsis showed similar results, with the higher down-regulation observed in the AtDFR and AtLDOX genes. These results suggest that VvMYB4-like may play an important role in regulation of anthocyanin biosynthesis in grapevine acting as a transcriptional repressor of flavonoid structural genes.
Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile.
J Ricardo
JR
Pérez-Díaz
Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile.
Jorge
J
Pérez-Díaz
Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile.
José
J
Madrid-Espinoza
Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile.
Enrique
E
González-Villanueva
Centro Tecnológico de la Vid y el Vino, Universidad de Talca, Av. Lircay s/n, Talca, Chile.
Yerko
Y
Moreno
Instituto de Ciencias Biológicas, Universidad de Talca, 2 Norte 685, Talca, Chile. sruiz@utalca.cl.
Simón
S
Ruiz-Lara
D000872:Anthocyanins / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D005419:Flavonoids / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D005638:Fruit / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D010802:Phylogeny; D010858:Pigmentation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D027843:Vitis / Q000235:genetics*
D000872:Anthocyanins; D005419:Flavonoids; D010940:Plant Proteins; D014157:Transcription Factors
Anthocyanin; Flavonoid; Grapevine; R2R3-MYB transcription factor; Transcriptional repressor; VvMYB4-like