Integrative physiological and transcriptomic analysis reveals chilling injury mechanisms in cold-stored persimmon fruit

Abstract

Persimmon is a chilling‑sensitive fruit, and low‑temperature storage frequently induces chilling injury (CI), characterized by flesh browning and gelation. To elucidate the mechanisms underlying CI, physiological traits and transcriptome responses were examined in ‘Youhou’ persimmon fruit maintained at 15 °C (non‑chilling control) and 1 °C (chilling treatment) over multiple storage intervals. Although storage at 1 °C significantly delayed fruit softening, CI became evident after 30 d and was accompanied by elevated levels of reactive oxygen species and malondialdehyde. Transcriptome profiling revealed progressive changes in gene expression during storage, whereas KEGG enrichment analysis indicated sequential activation of hormone signaling, antioxidant defense, and membrane-associated pathways. Weighted gene co‑expression network analysis (WGCNA) identified a gene module that showed the highest correlation with CI severity and oxidative stress-related traits. Functional enrichment indicated that genes within this module were predominantly distributed among pathways related to plant hormone signaling, glutathione metabolism, and starch and sucrose metabolism, together with genes involved in cell wall modification, kinase signaling, ubiquitination, and transcriptional regulation. Among these, genes encoding glutathione S‑transferase (GST) and trehalose‑6‑phosphate synthase (TPS) were significantly induced, whereas the polyamine oxidase (PAO) gene was also strongly up‑regulated. In addition, a core transcription factor network comprising MYB, ERF, ZAT, TCP, and bHLH was identified as a potential regulatory hub. These results suggest that CI in persimmon results from an imbalance between protective and damaging responses, with increased PAO expression potentially contributing to H₂O₂ accumulation and oxidative damage that eventually overwhelms the fruit’s defense system. These findings provide a mechanistic framework for understanding CI and identify potential targets for future postharvest intervention.