Chilling-Induced Metabolic Shifts and Flavor Changes in Dendrobium officinale Leaves

Refrigeration has become a common practice for preserving Dendrobium officinale products. The molecular mechanisms underlying chilling stress responses, particularly those linking physiological adaptation to flavor-related metabolite changes, remain unclear. This study aimed to explore the transcriptional and metabolic changes in D. officinale leaves during cold treatment and to identify key stress-responsive metabolites underlying flavor modulation and their roles in cold adaptation. Transcriptional clustering analysis revealed distinct expression profiles under varying temperatures, indicating that chilling temperatures affect pathways related to RNA processing, oxidative stress, and secondary metabolism. Metabolomics profiling demonstrated significant metabolite shifts over time, with lipids, organic acids, and phenylpropanoids being prominently altered. Notably, flavonoids like rutin and sugars like trehalose varied in their accumulation depending on the duration of cold exposure. Proteomic analysis indicated that proteins involved in amino acid metabolism and the TCA (tricarboxylic acid) cycle were significantly impacted by prolonged chilling, with amino acids (key osmoprotectants and flavor contributors) accumulating over time, linking cold stress adaptation to sensory quality enhancement. These findings suggest that a chilling temperature primarily affects metabolic flow at different time points, which could help control the quality of D. officinale leaves during cold storage.