title: Solar UV-B and ABA are involved in phenol metabolism of Vitis vinifera L. increasing biosynthesis of berry skin polyphenols.
abstract: It has been previously found that abscisic acid (ABA) participates in the activation of grapevine leaf tissue defense against potentially damaging effects of solar ultraviolet-B radiation (UV-B), apparently by triggering biosynthesis of phenols that filter the harmful radiation and act as antioxidants. The present work studies the effect of solar UV-B and exogenously applied ABA on berry growth, sugar accumulation, and phenol (anthocyanin and nonanthocyanin) profiles across berry development and ripening of Vitis vinifera L. cv. Malbec in a vineyard at 1450 m of altitude. The grapevines were exposed to relatively high UV-B irradiation (normal sunlight; +UV-B) and also to a reduced UV-B treatment (filter exclusion; -UV-B). These two UV-B treatments were combined with weekly spray applications to the leaves and berries of 1 mM ABA (+ABA) or H(2)O (-ABA). Reduction of UV-B delayed berry development and maturation, whereas the +UV-B and +ABA combined treatment hastened berry sugar and phenol accumulation. +UV-B/+ABA treatments also reduced berry growth and decreased sugar per berry without affecting sugar concentration (°Brix) at harvest. Berry skin ABA levels were higher in the +UV-B and +ABA combined treatment, which also hastened the onset of ripening up to 20 days. Berry skin ABA levels then decreased toward harvest, implying a possible role for ABA in the control of ripening in this nonclimacteric fruit. Under both +UV-B and +ABA treatments berry skin phenols were additively increased with a change in anthocyanin and nonanthocyanin profiles and increases in the proportion of phenols with high antioxidant capacity.
authors.affiliation: Instituto de Biología Agrícola de Mendoza, Facultad de Ciencias Agrarias, CONICET-Universidad Nacional de Cuyo, Chacras de Coria, Mendoza, Argentina.
authors.forename: Federico J
authors.initials: FJ
authors.lastname: Berli
authors.forename: Martín
authors.initials: M
authors.lastname: Fanzone
authors.forename: Patricia
authors.initials: P
authors.lastname: Piccoli
authors.forename: Rubén
authors.initials: R
authors.lastname: Bottini
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D005419:Flavonoids / Q000096:biosynthesis*; D005638:Fruit / Q000378:metabolism / Q000528:radiation effects; D010636:Phenols; D059808:Polyphenols; D014466:Ultraviolet Rays; D027843:Vitis / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects*
chemical_list: D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D000040:Abscisic Acid