Expression levels of an aquaporin (A) and a sucrose transporter (B) during berry development. Genes were normalized to individual and/or combined reference genes. Developmental stages are defined by growing degree days (GDD), which are calculated by taking the average of the daily high and low temperature each day compared to a baseline (10°C). Data points are compared relative to the first sampling stage, 208 GDD. During the 2004 season, veraison, which is the period of berry ripening initiation, occurred between 786 and 889 GDD.