title: Effects of UV exclusion on the physiology and phenolic composition of leaves and berries of Vitis vinifera cv. Graciano.
abstract: BACKGROUND
  Ultraviolet (UV) radiation induces adaptive responses that can be used for plant production improvement. The aim of this study was to assess the effect of solar UV exclusion on the physiology and phenolic compounds of leaves and berry skins of Vitis vinifera L. cv. Graciano under field conditions. Phenolic compounds were analyzed globally and individually in both the vacuolar fraction and, for the first time in grapevine, the cell wall-bound fraction. These different locations may represent diverse modalities of phenolic response to and protection against UV.
  
  
  RESULTS
  UV exclusion led to a decrease in Fv /Fm in leaves, revealing that solar UV is needed for adequate photoprotection. Only p-caffeoyl-tartaric acid from the soluble fraction of leaves and myricetin-3-O-glucoside from the soluble fraction of berry skins were significantly higher in the presence of UV radiation, and thus they could play a role in UV protection. Other hydroxycinnamic acids, flavonols, flavanols and stilbenes did not respond to UV exclusion.
  
  
  CONCLUSIONS
  UV exclusion led to subtle changes in leaves and berry skins of Graciano cultivar, which would be well adapted to current UV levels. This may help support decision-making on viticultural practices modifying UV exposure of leaves and berries, which could improve grape and wine quality.
authors.affiliation: Universidad de La Rioja, Edificio Científico-Tecnológico, Madre de Dios 51, E-26006, Logroño, Spain.
authors.forename: María-Ángeles
authors.initials: MÁ
authors.lastname: Del-Castillo-Alonso
authors.forename: María P
authors.initials: MP
authors.lastname: Diago
authors.forename: Laura
authors.initials: L
authors.lastname: Monforte
authors.forename: Javier
authors.initials: J
authors.lastname: Tardaguila
authors.forename: Javier
authors.initials: J
authors.lastname: Martínez-Abaigar
authors.forename: Encarnación
authors.initials: E
authors.lastname: Núñez-Olivera
mesh_terms: D000222:Adaptation, Physiological; D002109:Caffeic Acids / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D005419:Flavonoids / Q000378:metabolism; D005638:Fruit / Q000378:metabolism* / Q000528:radiation effects; D005960:Glucosides / Q000378:metabolism; D006801:Humans; D010636:Phenols / Q000032:analysis*; D018515:Plant Leaves / Q000378:metabolism* / Q000528:radiation effects; D013312:Stress, Physiological; D013472:Sunlight; D013644:Tartrates / Q000378:metabolism; D014466:Ultraviolet Rays; D014617:Vacuoles / Q000378:metabolism; D027843:Vitis / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D002109:Caffeic Acids; D005419:Flavonoids; D005960:Glucosides; D010636:Phenols; D013644:Tartrates; C474564:caffeoyl tartaric acid; C040015:myricetin
keywords: UV radiation; carotenoids; chlorophyll fluorescence; flavonols; grapevine; hydroxycinnamic acids; stilbenes; vacuolar and cell wall-bound fractions