title: ABA and GA3 increase carbon allocation in different organs of grapevine plants by inducing accumulation of non-structural carbohydrates in leaves, enhancement of phloem area and expression of sugar transporters.
abstract: Grape quality for winemaking depends on sugar accumulation and metabolism in berries. Abscisic acid (ABA) and gibberellins (GAs) have been reported to control sugar allocation in economically important crops, although the mechanisms involved are still unknown. The present study tested if ABA and gibberellin A3 (GA3) enhance carbon allocation in fruits of grapevines by modifying phloem loading, phloem area and expression of sugar transporters in leaves and berries. Pot-grown Vitis vinifera cv. Malbec plants were sprayed with ABA and GA3 solutions. The amount of soluble sugars in leaves and berries related to photosynthesis were examined at three points of berry growth: pre-veraison, full veraison and post-veraison. Starch levels and amylase activity in leaves, gene expression of sugar transporters in leaves and berries and phloem anatomy were examined at full veraison. Accumulation of glucose and fructose in berries was hastened in ABA-treated plants at the stage of full veraison, which was correlated with enhancement of Vitis vinifera HEXOSE TRANSPORTER 2 (VvHT2) and Vitis vinifera HEXOSE TRANSPORTER 6 (VvHT6) gene expression, increases of phloem area and sucrose content in leaves. On the other hand, GA3 increased the quantity of photoassimilates delivered to the stem thus increasing xylem growth. In conclusion, stimulation of sugar transport by ABA and GA3 to berries and stems, respectively, was due to build-up of non-structural carbohydrates in leaves, modifications in phloem tissue and modulation in gene expression of sugar transporters.
authors.affiliation: Facultad de Ciencias Agrarias, CONICET-UNCuyo, Instituto de Biología Agrícola de Mendoza, Chacras de Coria, Argentina.
authors.forename: Germán
authors.initials: G
authors.lastname: Murcia
authors.affiliation: Facultad de Ciencias Agrarias, CONICET-UNCuyo, Instituto de Biología Agrícola de Mendoza, Chacras de Coria, Argentina.|Departamento de Fisiología y Bioquímica Vegetal, EEA-INTA La Consulta, La Consulta, Argentina.
authors.forename: Mariela
authors.initials: M
authors.lastname: Pontin
authors.affiliation: Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, UNRC, Río Cuarto, Argentina.
authors.forename: Herminda
authors.initials: H
authors.lastname: Reinoso
authors.affiliation: Instituto di Biometeorologia, CNR, Bologna, Italia.
authors.forename: Rita
authors.initials: R
authors.lastname: Baraldi
authors.affiliation: Instituto di Biometeorologia, CNR, Bologna, Italia.
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Bertazza
authors.affiliation: Departamento de Virología, EEA-INTA Mendoza, Luján de Cuyo, Argentina.
authors.forename: Sebastián
authors.initials: S
authors.lastname: Gómez-Talquenca
authors.affiliation: Facultad de Ciencias Agrarias, CONICET-UNCuyo, Instituto de Biología Agrícola de Mendoza, Chacras de Coria, Argentina.
authors.forename: Rubén
authors.initials: R
authors.lastname: Bottini
authors.affiliation: Facultad de Ciencias Agrarias, CONICET-UNCuyo, Instituto de Biología Agrícola de Mendoza, Chacras de Coria, Argentina.
authors.forename: Patricia N
authors.initials: PN
authors.lastname: Piccoli
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D018533:Biomass; D002241:Carbohydrates / Q000737:chemistry*; D002244:Carbon / Q000378:metabolism*; D005638:Fruit / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000494:pharmacology*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D052585:Phloem / Q000187:drug effects / Q000378:metabolism*; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D054046:Plant Stomata / Q000166:cytology / Q000235:genetics / Q000502:physiology; D013213:Starch / Q000378:metabolism; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism; D027843:Vitis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D052584:Xylem / Q000187:drug effects / Q000378:metabolism
chemical_list: D002241:Carbohydrates; D005875:Gibberellins; D026901:Membrane Transport Proteins; D010940:Plant Proteins; D000040:Abscisic Acid; D002244:Carbon; D013213:Starch; C007842:gibberellic acid