Blue light treatment enhances fruit wound repair and inhibits blue mold in destemmed grapes.

Destemmed grapes are gaining popularity as a convenient fresh-cut fruit. However, they are highly susceptible to mechanical damage during processing, which accelerates berry decay. In this study, we investigated the effects of blue light (BL) treatment on wound repair and the control of fungal pathogens of destemmed grapes. The results showed that BL treatment significantly enhanced wound repair in destemmed grapes, inhibited spore germination and mycelial growth of Penicillium griseofulvum, and reduced fruit decay caused by the pathogen in vivo. BL treatment increased total phenolic content and enhanced the activities of key enzymes in phenolic metabolism in grape berries, including polyphenol oxidase (PPO), peroxidase (POD), and phenylalanine ammonia-lyase (PAL). Transcriptomic analysis of grape berries revealed that BL treatment upregulated genes associated with photosynthesis, cell wall and callus synthesis, stress response, and carbon metabolism, thereby facilitating wound repair in fruit. Fungal diversity analysis demonstrated that BL treatment increased the diversity of fungal communities on the grape berries, enriched beneficial yeasts (Meyerozyma, Vishniacozyma) and suppressed pathogenic genera (Aspergillus, Penicillium), effectively controlling berry decay. The results suggest that application of BL treatment could be a potential strategy to maintain the berry quality of destemmed grapes.