Falginella, L.; Magris, G.; Castellarin, S. D.; Gambetta, G. A.; Matthews, M. A.; Morgante, M.; Di Gaspero, G.

Understanding ripening patterns and governing ripening speed are central aspects of grapevine (Vitis vinifera) berry biology owing to the importance of grape ripeness in winemaking. Despite this, the genetic control of ripening is largely unknown. Here, we report a major quantitative trait locus that controls ripening speed, expressed as speed of sugar accumulation. A haplotype originating from the species Vitis riparia halves maximum speed regardless of crop levels and berry sizes. The sequence of events that are normally completed at the onset of ripening in a two-week period known in viticulture as veraison are taking place at a slower speed, thereby attaining ripeness under milder weather conditions in late summer. V. vinifera cultivars show limited phenotypic variation for ripening speed and no selective sweep in the causal genomic region that could derive from domestication or improvement. Closely related species make up for the lack of standing variation, supplying major effect alleles for adapting grape cultivars to climate change.