Integrated transcriptomic and metabolomic analysis reveals the regulatory mechanisms of low-temperature storage on nutritional quality in Brassica alboglabra

• 0°C storage is optimal for preserving the nutritional quality of Brassica alboglabra. • Low temperature preserves nutrients by suppressing PAO, CCD , and AO expression. • Low temperature suppresses COMT1 and CAD , reducing phenolics to delay senescence in Brassica alboglabra. • Low temperature inhibits SOT17, CYP83B1 , and UGT74E2 expression, reducing glucosinolate biosynthesis. Low-temperature storage is a key strategy for preserving the postharvest sensory qualities and nutritional value of fruits and vegetables. However, the regulatory mechanisms by which low temperatures influence the nutritional quality of Brassica alboglabra remain poorly understood. In this study, B. alboglabra was stored at 0 °C, 5 °C, and 25 °C to evaluate the effects of storage temperature on its physiological and nutritional attributes. Transcriptomic and metabolomic analyses were performed to explore the underlying mechanisms. Results showed that B. alboglabra lost commercial value after just three days at 25 °C. Storage at 5 °C reduced weight loss and preserved higher levels of glucoraphanin, glucobrassicin, and neoglucobrassicin. In contrast, storage at 0 °C was most effective in retaining ascorbic acid, chlorophyll, β -carotene, and two glucosinolates: sinigrin and gluconapin. Additionally, total glucosinolate and phenolic contents were higher at 0 °C than at 5 °C. Transcriptomic analysis revealed that, compared to 25 °C, storage at 0 °C suppressed the expression of genes associated with chlorophyll degradation ( PAO ), β -carotene breakdown ( CCD1 ), ascorbic acid metabolism ( AO ), phenolic biosynthesis ( COMT1, CAD ), and glucosinolate biosynthesis ( SOT17, CYP83B1, UGT74E2 ). Metabolomic profiling indicated that low temperatures inhibited the accumulation of most metabolites. Specifically, 0 °C storage reduced levels of syringin, 1-O-sinapoyl- β -D-glucose, and glucosinolates including 4-methoxyglucobrassicin, glucoalyssin, and neoglucobrassicin. Integrated analyses suggested that low-temperature storage downregulated CAD -related enzymes and COMT1 gene expression, thereby reducing syringin and 1-O-sinapoyl- β -D-glucose accumulation. These findings provide new insights into the molecular responses of B. alboglabra to postharvest storage temperature and offer a theoretical basis for strategies to prolong shelf life and maintain commercial quality.