Differential responses of sugar, organic acids and anthocyanins to source-sink modulation in Cabernet Sauvignon and Sangiovese grapevines

Natalia Bobeica (1) , Stefano Poni , Ghislaine Hilbert (1) , Christel Renaud (1) , Eric Gomes (1) , Serge Delrot (1) , Zhanwu Dai (1)

1 UMR EGFV - Ecophysiologie et Génomique Fonctionnelle de la Vigne

Grape berry composition mainly consists of primary and secondary metabolites. Both are sensitive to environment and viticultural management. As a consequence, climate change can affect berry composition and modify wine quality and typicity. Leaf removal techniques can impact berry composition by modulating the source-to-sink balance and, in turn, may mitigate some undesired effects due to climate change. The present study investigated the balance between technological maturity parameters such as sugars and organic acids, and phenolic maturity parameters such as anthocyanins in response to source-sink modulation. Sugar, organic acid, and anthocyanin profiles were compared under two contrasting carbon supply levels in berries of cv. Cabernet Sauvignon and Sangiovese collected at 9 and 14 developmental stages respectively. In addition, whole-canopy net carbon exchange rate was monitored for Sangiovese vines and a mathematic model was used to calculate the balance between carbon fixation and berry sugar accumulation. Carbon limitation affected neither berry size nor the concentration of organic acids at harvest. However, it significantly reduced the accumulation of sugars and total anthocyanins in both cultivars. Most interestingly, carbon limitation decreased total anthocyanin concentration by 84.3% as compared to the non source-limited control, whereas it decreased sugar concentration only by 27.1%. This suggests that carbon limitation led to a strong imbalance between sugars and anthocyanins. Moreover, carbon limitation affected anthocyanin profiles in a cultivar dependent manner. Mathematical analysis of carbon-balance indicated that berries used a higher proportion of fixed carbon for sugar accumulation under carbon limitation (76.9%) than under carbon sufficiency (48%). Thus, under carbon limitation, the grape berry can manage the metabolic fate of carbon in such a way that sugar accumulation is maintained at the expense of secondary metabolites.

Mots clés: Vitis Vinifera L; Wine Alcohol Content; Wine Color; Climate Change; Leaf-To-Fruit Ratio; Berry Composition

Mots clés: Vitis Vinifera; Vigne; Sangiovese; Vignoble; Canopée; Métabolite; Anthocyanine; Qualité de la baie; Typicité du vin; Maturité phénolique; Accumulation du carbone; Acide organique; Analyse mathématique; Cabernet Sauvignon; Baie de raisin; Changement climatique

Domaines: Biologie végétale

Natalia Bobeica, Stefano Poni, Ghislaine Hilbert, Christel Renaud, Eric Gomes, et al.. Differential responses of sugar, organic acids and anthocyanins to source-sink modulation in Cabernet Sauvignon and Sangiovese grapevines. Frontiers in Plant Science, In press, 6, 14 p. ⟨10.3389/fpls.2015.00382⟩. ⟨hal-02514390⟩