title: Characterization of major ripening events during softening in grape: turgor, sugar accumulation, abscisic acid metabolism, colour development, and their relationship with growth.
abstract: Along with sugar accumulation and colour development, softening is an important physiological change during the onset of ripening in fruits. In this work, we investigated the relationships among major events during softening in grape (Vitis vinifera L.) by quantifying elasticity in individual berries. In addition, we delayed softening and inhibited sugar accumulation using a mechanical growth-preventing treatment in order to identify processes that are sugar and/or growth dependent. Ripening processes commenced on various days after anthesis, but always at similarly low elasticity and turgor. Much of the softening occurred in the absence of other changes in berry physiology investigated here. Several genes encoding key cell wall-modifying enzymes were not up-regulated until softening was largely completed, suggesting softening may result primarily from decreases in turgor. Similarly, there was no decrease in solute potential, increase in sugar concentration, or colour development until elasticity and turgor were near minimum values, and these processes were inhibited when berry growth was prevented. Increases in abscisic acid occurred early during softening and in the absence of significant expression of the V. vinifera 9-cis-epoxycarotenoid dioxygenases. However, these increases were coincident with decreases in the abscisic acid catabolite diphasic acid, indicating that initial increases in abscisic acid may result from decreases in catabolism and/or exogenous import. These data suggest that softening, decreases in turgor, and increases in abscisic acid represent some of the earliest events during the onset of ripening. Later, physical growth, further increases in abscisic acid, and the accumulation of sugar are integral for colour development.
authors.affiliation: Wine Research Centre, the University of British Columbia, 2205 East Mall, Vancouver, BC V6T1Z4, Canada Dipartimento di Scienze Agrarie ed Ambientali, University of Udine, 33100 Udine, Italy.
authors.forename: Simone D
authors.initials: SD
authors.lastname: Castellarin
authors.affiliation: Institut des Sciences de la Vigne et du Vin (ISVV), 210 Chemin de Leysotte, CS 50008, 33882 Villenave D'Ornon, France.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Gambetta
authors.affiliation: National Agriculture and Food Research Organization, Kyushu Okinawa Agricultural Research Center, 496 Izumi, Chikugo, Fukuoka 833-0041, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wada
authors.affiliation: Department of Viticulture and Enology, University of California at Davis, 1 Shields Avenue, Davis, CA 95616, USA.
authors.forename: Mark N
authors.initials: MN
authors.lastname: Krasnow
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nevada, 1664 North Virginia Street, Reno, NV 89557, USA.
authors.forename: Grant R
authors.initials: GR
authors.lastname: Cramer
authors.affiliation: Dipartimento di Scienze Agrarie ed Ambientali, University of Udine, 33100 Udine, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Peterlunger
authors.affiliation: Department of Plant Sciences, University of California at Davis, 1 Shields Avenue, Davis, CA 95616, USA.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Shackel
authors.affiliation: Department of Viticulture and Enology, University of California at Davis, 1 Shields Avenue, Davis, CA 95616, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Matthews
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D000872:Anthocyanins / Q000378:metabolism; D002241:Carbohydrates / Q000032:analysis*; D002473:Cell Wall / Q000201:enzymology; D004548:Elasticity; D005638:Fruit / Q000254:growth & development* / Q000378:metabolism* / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D010858:Pigmentation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012995:Solubility; D027843:Vitis / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D000872:Anthocyanins; D002241:Carbohydrates; D010940:Plant Proteins; D000040:Abscisic Acid
keywords: Anthocyanins; Vitis vinifera L.; cell wall; elasticity; firmness; fruit development