Integrative Analysis of Transcriptomic and Metabolomic Profiles Identifies Distinct Dynamic Changes in Primary and Secondary Metabolites in Grape Berries Under Fruit-Specific Light Exposure

Light influences fruit development and quality through two primary pathways: its effect on vegetative organs, which subsequently impacts the fruit, and its direct effect on the fruit itself. While the mechanism of the former pathway is well-documented, the direct impact of light on fruit has been less studied due to limitations in applying controlled light exposure to preharvest fruit. This study addresses this gap by developing a novel device that delivers fruit-specific light treatment, enabling precise light exposure without altering the light conditions of vegetative tissues. The integration of metabolomics and transcriptomics reveals that light can directly affect the growth and development of fruits and the formation of quality, independent of the vegetative organs. Our findings reveal distinct regulatory patterns for primary and secondary metabolites during maturation. Direct light exposure activates primary metabolites and photosynthetic gene expression, though this effect diminishes as the fruit matures. Conversely, light enhances secondary metabolites, such as flavonoids, and their associated gene expressions, maintaining consistent activation throughout development and leading to higher accumulation during maturation. This study provides the first transcriptomic and metabolomic characterization of grape berries exposed to fruit-specific light treatment, advancing our understanding of light-dependent fruit development and quality formation mechanisms.