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

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. • Peel browning affects the marketability and quality of oriental melons. • Cultivar-dependent surface protection and stress responses associates with browning tolerance. • Cuticle remodeling strengthens epidermal protection and reduces peel browning. • Auxin signaling associates with cuticle reinforcement and reduced browning.