Sweet grapes do not happen by accident. As berries ripen, the plant has to move, make, and store sugars with remarkable timing, and even small shifts can affect flavor, harvest quality, and market value. A new study in Horticulture Research traces part of that process to a specific molecular chain in grapes, showing how the ripening hormone abscisic acid, or ABA, helps drive sugar buildup. Researchers at Shanghai Jiao Tong University found that ABA sped ripening in ‘Muscat Hamburg’ grapes and increased soluble sugar accumulation, then linked that change to two transcription factors, VvMYB44 and VvERF045, and a sucrose-related gene called VvSPS4. The findings gives grape biology a more defined route between hormone signaling and sweetness. Rather than treating ABA as a broad ripening signal with many downstream effects, the study identifies a narrower control point tied to sucrose metabolism. That matters because sweetness is one of the traits people notice first. The findings gives grape biology a more defined route between hormone signaling and sweetness. (CREDIT: Shutterstock) ABA pushed berries along faster The team …