Primary and secondary metabolites are major components of grape composition and their balances define wine typicality. Global climate change is modifying vine physiology and especially the composition of grape berries at harvest, by decoupling phenolic and aromatic maturities (depending on secondary metabolites) from technical maturity (depending on primary metabolites). These modifications can be limited through vineyard management. One of the rapid and efficient ways to mitigate the effects of climate change is to modify vine canopy, thus modifying the relationships between source and sink.
To face this challenge, we used Vitis vinifera cv. Cabernet Sauvignon plants 1) to analyse the response of yield and biochemical composition in ripening berries, including sugars, organic acids, amino acids, phenolic compounds (anthocyanins, flavonols) and aroma molecular makers including methoxypyrazines associated with the green character (low ripenning), volatile thiols (and their precursors), as well as furanones and lactones linked with the cooked/dried fruit aromas (overipenning), with UHPLC, GC-MS and LC-MS analyses; 2) to link the changes in berry composition with wine quality by microvinification sensory analysis; 3) to study the response of berry transcriptome to canopy manipulation, by RNAseq or qPCR analyses.
The results showed that metabolites had different sensitivities to the modulation of leaf-to-fruit ratios, demonstrating that it is possible to determine an optimal leaf/fruit ratio to reduce sugar concentration in the berry without much impact on the typicality of Bordeaux wines.
Acknowledgments: We thank the CIVB for financial support to the CANOGRAPE project N ° 44233 and France AgriMer for financial support to CANABA project N°414.
Authors: Sabine Guillaumie (1), Eloïse Brouard (1), Lina Wang (1), Ghislaine Hilbert (1), Cécile Thibon (2), Isabelle Merlin (1), Alexandre Pons (2,3), Christel Renaud (1), Claudine Trossat-Magnin (1), Nathalie Ollat (1), Serge Delrot (1), Philippe Darriet (2), Eric Gomès (a), Zhanwu Dai (1), Sabine Guillaumie (1)
(1) UMR EGFV, Bordeaux Sciences Agro, INRA, University of Bordeaux, ISVV, Villenave d’Ornon, France
(2) Unitéde recherche Oenologie, EA 4577, USC 1366 INRA, ISVV, Universitéde Bordeaux, Bordeaux INP, F33882 Villenave d’Ornon France
(3) SEGUIN MOREAU France, Cognac, France
Keywords: climate change, leaf/fruit ratio, berry composition, wine