Cultivar-dependent peel browning in oriental melon is associated with surface protection and stress response regulation during storage

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Peel browning during storage severely limits the marketability of oriental melons. However, the underlying molecular mechanisms remain unclear. This study investigated the mechanism using two cultivars with contrasting susceptibility: ‘Alchankkul’ (browning-sensitive) and ‘Eliteggul’ (browning-tolerant), stored at 20 °C for 7 d or 4 °C for 14 d followed by 3 d at 20 °C (retail simulation). ‘Eliteggul’ exhibited less browning, lower weight loss, and firmer texture than ‘Alchankkul’. In ‘Alchankkul’, 20 °C storage promoted brittle cutin enriched in aromatics, impairing moisture retention. By contrast, ‘Eliteggul’ accumulated greater cuticle mass enriched in alkanes, especially under retail conditions following cold storage. Multi-level analyses indicated that cultivar differences in epidermal protection and stress tolerance were closely associated with storage outcomes. Transcriptomic and metabolomic analyses revealed upregulation of cuticle-related genes and metabolites, induction of phospholipid, antioxidant, and inositol pathways that reinforced membranes and reduced chilling injury. Elevated indole-3-acetic acid and auxin-related gene expression further suggest auxin-mediated cuticle reinforcement Collectively, these findings provide a physiological and molecular framework for understanding peel browning differences among oriental melon cultivars and identify candidate regulatory processes relevant to postharvest quality management.