Abscisic acid and gibberellins increase sugar content and vascular bundles area in grapevine berries (Vitis vinifera L. cv Malbec)

MURCIA G, PONTIN M, REINOSO H, BOTTINI R, TALQUENCA S, BARALDI R, PICCOLI P

Shanghai

Conferencia; 21st International Conference of Plant Growth Substances; 2013

Abscisic acid (ABA) and gibberellins (GA) increase color and sugar content in table grape varieties but little is known about their action regarding sugar content in grapevine cultivars. So, this work was aimed in the transport of sugars from the leaves to the berries at veraison stage (50% colored grapes) in Vitis vinifera L. cv Malbec plants. Two-year-old-potted grapevines were sprayed weekly since fruit set until veraison with ABA (250 ppm), GA3 (500 ppm), uniconazole (a GA3 inhibitor, 100 ppm) and control (water + Triton X-100 0,1% v/v). At the end of the experiment physiological, morphological and biochemical parameters were measured. It was found that there was an increase of sugar content in berries of plants treated with ABA and GA3 correlated with a major xylem and phloem area in berrie pedicels in these treatments. Photosynthetic differences were not found between ABA and GA3 treatments and the control. Furthermore there was an increase of root fresh weight and a decrease of stomata conductance and stomata index in plants sprayed with ABA and uniconazole which resulted in plants with higher water potential. We concluded that the greater sugar content in ABA and GA3 –treated-grapevines was due partially to an increment in vascular bundles area of pedicels. Gene expression assays are being conducted to observe if these hormones might overexpress hexose transporters and vacuolar and/or cell wall invertases genes which would explain the higher sugar content in berries parenchyma cells when symplastic sugar uptake becomes apoplastic at veraison.