Beyond a simple oxidation reaction: the complex molecular network regulating fruit and vegetable browning

Abstract

Fruit and vegetable browning is a complex physiological phenomenon responsible for substantial postharvest losses and profound economic consequences. While enzymatic oxidation mediated by oxidative enzymes has long been considered the core mechanism, emerging evidence highlights the flavonoid pathway as an alternative route, influencing pigmentation outcomes. Browning is governed by a multitiered regulatory network spanning molecular, biochemical, cellular, and physiological levels, which encompasses transcriptional, post-transcriptional, epigenetic, and hormonal controls. Notably, regulatory mechanisms exhibit both conserved features and species-specific variations, reflecting potential adaptive evolution that may underlie differential browning responses across species. Here, we provide a thorough review of current advances in the mechanistic understanding of browning, with emphasis on providing evidence on multilevel regulations, identifying conserved mechanisms versus species-specific variations, exploring their contributions to differential browning responses, and providing viable strategies for browning management through the application of exogenous hormones. Based on these, the current research landscape is critically assessed, and future research priorities are identified.