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 (AsA) 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 (TF) genes (MaWRKY11/18/40/50/60). DNA affinity purification sequencing (DAP-seq) and yeast one-hybrid (Y1H) confirmed these WRKYs can bind to W-box motifs in the ascorbate oxidase (MaAAO1) promoter. This activation triggered AsA depletion and reactive oxygen species (ROS) accumulation, accelerating peel browning. Conversely, AsA 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 AsA disrupts this cascade by coupling redox signaling to lactylation-dependent chromatin silencing. Our study unveils a redox-sensitive epigenetic switch wherein exogenous AsA mitigates chilling injury by repressing oxidative pathways via histone lactylation, offering strategies for preserving tropical fruit quality.