Histone lactylation mediates exogenous ascorbic acid suppression of chilling-induced peel browning in banana

Banana (Musa spp.) fruit peel browning during cold storage results in significant postharvest losses; however, the molecular mechanisms linking antioxidant metabolism and transcriptional regulation remain unclear. Here, we demonstrate that exogenous ascorbic acid alleviates chilling-induced browning by suppressing the WRKY-AAO regulatory module through histone H3K18 lactylation (H3K18la)-mediated chromatin remodeling. DNase-seq analyses revealed that cold stress induces chromatin accessibility at the promoters of WRKY transcription factor genes (MaWRKY11/18/40/50/60). DNA affinity purification sequencing (DAP-seq) and yeast one-hybrid confirmed these WRKYs can bind to W-box motifs in the ascorbate oxidase (MaAAO1) promoter. This activation triggered ascorbic acid depletion and reactive oxygen species accumulation, accelerating peel browning. Conversely, ascorbic acid treatment reduced H3K18la levels at MaWRKY genes, diminishing their accessibility and lowering the expression of MaWRKY target genes. Transient overexpression assays confirmed that MaAAO1 drives peel browning, while ascorbic acid disrupts this cascade by coupling redox signaling to lactylation-dependent chromatin silencing. Our study unveils a redox-sensitive epigenetic switch wherein exogenous ascorbic acid mitigates chilling injury by repressing oxidative pathways via histone lactylation, offering strategies for preserving tropical fruit quality.