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

MURCIA G; PONTIN M; REYNOSO H; BARALDI R; BERTAZZA G; TALQUENCA S; BOTTINI R; PICCOLI P

PHYSIOLOGIA PLANTARUM

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015

0031-9317

Grape quality for winemaking depends on sugar accumulation and 21 metabolism in berries. Abscisic acid (ABA) and gibberellins (GAs) have 22 been reported to control sugar allocation in economically important crops, 23 although the mechanisms involved are still unknown. This study tested 24 if ABA and gibberellin A3 (GA3) enhance carbon allocation in fruits of 25 grapevines by modifying phloem loading, phloem area and expression of 26 sugar transporters in leaves and berries. Pot-grown Vitis vinifera cv. Malbec 27 plants were sprayed with ABA and GA3 solutions. The amount of soluble 28 sugars in leaves and berries related to photosynthesis were examined at three 29 points of berry growth: pre-veraison, full veraison and post-veraison. Starch 30 levels and amylase activity in leaves, gene expression of sugar transporters 31 in leaves and berries and phloem anatomy were examined at full veraison. 32 Accumulation of glucose and fructose in berries was hastened in ABA-treated 33 plants at the stage of full veraison, which was correlated with enhancement 34 of Vitis vinifera HEXOSE TRANSPORTER 2 (VvHT2) and Vitis vinifera HEXOSE 35 TRANSPORTER 6 (VvHT6) gene expression, increases of phloem area and 36 sucrose content in leaves. On the other hand, GA3 increased the quantity 37 of photoassimilates delivered to the stem so increasing xylem growth. In 38 conclusion, stimulation of sugar transport by ABA and GA3 to berries and 39 stems, respectively, was due to build-up of non-structural carbohydrates in 40 leaves, modifications in phloem tissue and modulation in gene expression of 41 sugar transporters.