Publications by authors named "Sandrine Vialet"

Grapevine (Vitis vinifera L.) berry synthesizes and accumulates a large array of phenolic compounds (e.g.

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Grapevine organs accumulate anthocyanins in a cultivar-specific and environmentally induced manner. The MYBA1-A2 genes within the berry color locus in chromosome 2 represent the major genetic determinants of fruit color. The simultaneous occurrence of transposon insertions and point mutations in these genes is responsible for most white-skinned phenotypes; however, the red pigmentation found in vegetative organs suggests the presence of additional regulators.

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In plants, the shikimate pathway provides aromatic amino acids that are used to generate numerous secondary metabolites, including phenolic compounds. In this pathway, shikimate dehydrogenases (SDH) 'classically' catalyse the reversible dehydrogenation of 3-dehydroshikimate to shikimate. The capacity of SDH to produce gallic acid from shikimate pathway metabolites has not been studied in depth.

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Grapevine (Vitis) is considered to be one of the major fruit crops in the world based on hectares cultivated and economic value. Grapes are used not only for wine but also for fresh fruit, dried fruit, and juice production. Wine is by far the major product of grapes, and the focus of this chapter is on wine grape cultivars.

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Article Synopsis
  • Flavonoids, particularly proanthocyanidins (PAs), are important compounds in grapes that affect the quality of fruit and wine, yet their regulatory mechanisms are not well understood.
  • The study identified 21 expression quantitative trait loci (eQTLs) related to PA synthesis genes, revealing a polygenic regulatory mechanism behind their biosynthesis.
  • A specific gene, VvMYBC2-L1, was highlighted for its role in regulating PA production, as its overexpression decreased PA levels and down-regulated PA-related genes.
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Accumulation of anthocyanins in the exocarp of red grapevine (Vitis vinifera) cultivars is one of several events that characterize the onset of grape berry ripening (véraison). Despite our thorough understanding of anthocyanin biosynthesis and regulation, little is known about the molecular aspects of their transport. The participation of ATP binding cassette (ABC) proteins in vacuolar anthocyanin transport has long been a matter of debate.

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Proanthocyanidins (PA) play a major role in plant protection against biotic and abiotic stresses. Moreover these molecules are known to be beneficial for human health and are responsible for astringency of foods and beverages such as wine and thus have a great impact on the final quality of the product. Genes playing a role in the PA pathway are only partially known.

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Article Synopsis
  • eQTL mapping is a technique used to understand how genetic variations affect gene expression, which contributes to natural differences in characteristics, but it’s rarely used in woody plants due to sampling challenges.
  • The researchers focused on grapevine and analyzed a key enzyme (VvUFGT) involved in berry color, using data from a specific cross of grape varieties (Syrah and Grenache) to perform the mapping in a controlled field experiment.
  • They discovered two significant eQTLs: one that directly affects VvUFGT expression (cis-eQTL) and one that influences it indirectly (trans-eQTL) through related transcription factors, providing valuable insights into the genetics of grape skin color.
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In grapevine (Vitis vinifera), anthocyanins are responsible for most of the red, blue, and purple pigmentation found in the skin of berries. In cells, anthocyanins are synthesized in the cytoplasm and accumulated into the vacuole. However, little is known about the transport of these compounds through the tonoplast.

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Grapevine (Vitis vinifera) proanthocyanidins contribute to plant defense mechanisms against biotic stress and also play a critical role in organoleptic properties of wine. In grapevine berry, these compounds are mainly accumulated in exocarps and seeds in the very early stages of development. A previous study has already identified VvMybPA1 as the first transcription factor involved in the regulation of the proanthocyanidin pathway during seed development in grapevine.

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The colour of the red wine is essentially due to the release of anthocyanins from the red skin of grape berries during the process of wine making. Anthocyanins are synthesized during ripening of the berries under the control of VvMYBA1 transcription factor that controls the expression of UFGT. In order to identify the whole set of downstream regulated genes, we targeted constitutive ectopic expression of VlmybA1-2 into grapevine hairy roots and plants.

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An extraction method on grape berry was optimized for the total flavan-3-ol content measurement with regard to the nature of the sample and the duration of its extraction. This extraction was performed for the first time on the whole pericarp. Flavan-3-ol extractions were achieved on Shiraz ripe samples of pericarp versus skin within different durations: the best results were obtained for the whole pericarp and 1 h duration.

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