title: Impact of diurnal temperature variation on grape berry development, proanthocyanidin accumulation, and the expression of flavonoid pathway genes.
abstract: Little is known about the impact of temperature on proanthocyanidin (PA) accumulation in grape skins, despite its significance in berry composition and wine quality. Field-grown grapes (cv. Merlot) were cooled during the day or heated at night by +/-8 °C, from fruit set to véraison in three seasons, to determine the effect of temperature on PA accumulation. Total PA content per berry varied only in one year, when PA content was highest in heated berries (1.46 mg berry(-1)) and lowest in cooled berries (0.97 mg berry(-1)). In two years, cooling berries resulted in a significant increase in the proportion of (-)-epigallocatechin as an extension subunit. In the third year, rates of berry development, PA accumulation, and the expression levels of several genes involved in flavonoid biosynthesis were assessed. Heating and cooling berries altered the initial rates of PA accumulation, which was correlated strongly with the expression of core genes in the flavonoid pathway. Both heating and cooling altered the rate of berry growth and coloration, and the expression of several structural genes within the flavonoid pathway.
authors.affiliation: Department of Food Science and Technology, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Seth D
authors.initials: SD
authors.lastname: Cohen
authors.forename: Julie M
authors.initials: JM
authors.lastname: Tarara
authors.forename: Greg A
authors.initials: GA
authors.lastname: Gambetta
authors.forename: Mark A
authors.initials: MA
authors.lastname: Matthews
authors.forename: James A
authors.initials: JA
authors.lastname: Kennedy
mesh_terms: D053898:Biosynthetic Pathways; D005419:Flavonoids / Q000096:biosynthesis*; D005638:Fruit / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D044945:Proanthocyanidins / Q000096:biosynthesis*; D013696:Temperature; D027843:Vitis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005419:Flavonoids; D010940:Plant Proteins; D044945:Proanthocyanidins; C013221:proanthocyanidin