Comparative metabolome and transcriptome analyses reveal the role of MeJA in improving postharvest disease resistance and maintaining the quality of Rosa roxburghii fruit

Rosa roxburghii has a short and concentrated harvest period, during which rapid decay and quality deterioration at room temperature pose significant challenges to the supply chain. To address this, we applied methyl jasmonate (MeJA) treatment and stored the fruit at low temperatures. MeJA treatment effectively reduced decay, maintained fruit firmness and brightness, suppressed respiration, and decreased malondialdehyde content. Further analysis revealed that MeJA reduced hydrogen peroxide levels by boosting the activities and gene expressions of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Additionally, MeJA upregulated the expression of disease resistance-related genes (RrRGA3, RrPPO, RrCHIT, RrPRB1, and RrRPM1). It also stimulated genes involved in the AsA synthesis and AsA-GSH cycle (RrMIXO, RrAKRC9, RrDHAR, and RrGPX), thereby increasing AsA content. Moreover, MeJA promoted the activities (PAL, C4H, and 4CL) and gene expressions (RrPAL, Rr4CL, RrCSE, RrCCR, RrPGT, RrHCT, RrDFR and RrERF114) of phenylpropane metabolism, resulting in increased levels of L-phenylalanine, caffeic acid, phlorizin, and other phenolic acids and lignin content. Furthermore, MeJA induced the expression of genes related to JA biosynthesis (RrAOC, RrOPR, and RrACX), and abscisic acid synthesis (RrNCED). In conclusion, these findings suggest that MeJA treatment enhances disease resistance and preserves the postharvest quality of R. roxburghii, making it a promising preservation method for large-scale commercial application in fruit storage.