Transcriptomic analysis reveals lncRNA/circRNA-driven pathways in UV-C-induced chilling tolerance in green pepper

Low-temperature storage can induce chilling injury (CI) in green peppers ( Capsicum annuum L.), which drastically reduces their postharvest quality. However, exposure to ultraviolet (UV-C) irradiation helps mitigate these adverse effects. In this study, physiological and transcriptomic analyses were utilized to elucidate the response of green pepper fruit to low temperature storage and UV-C treatment. UV-C treatment was found to substantially counteract CI effects in green peppers subjected to 7 days of storage at 1 o C. The intervention reduced softening rates, limited electrolyte leakage, and improved the CI index, resulting in enhanced storability and quality retention. Transcriptomic profiling revealed 2,000 differentially expressed long non-coding RNAs (lncRNAs) and 11 circular RNAs (circRNAs) in UV-C-treated fruit, relative to the T group. Profiling also identified 5,190 differentially expressed genes (DEGs) in UV-C-treated fruit compared to non-UV-C treated fruit stored at 1 °C. UV-C irradiation induced metabolic reprogramming of sugar pathways, altering the expression pattern of 43 genes associated with UDP-glucose and β-D-glucose regulation. UV-C also enhanced glutathione pathway activity, impacting the expression of 41 pathway-related genes. UV-C activated fatty acid metabolism, a critical pathway in abiotic stress signaling, resulting in the identification of 34 DEGs implicated in CI mitigation. In summary, UV-C treatment effectively mitigated CI in cold-stored green peppers through regulation of mRNA and non-coding RNA expression. Our study provides valuable physiological and molecular insights into postharvest quality maintenance in green pepper fruit.