Multi-omics analysis reveals that ethylene signaling regulates petal color fading in cut peony flowers via phytohormonal imbalance and oxidative stress

Petal color fading in cut flowers of the herbaceous peony 'Coral Sunset' coincides with flower senescence, yet the underlying physiological and molecular mechanisms remain poorly understood. In this study, we integrated physiological, transcriptomic, and metabolomic data to elucidate how 2 h pulse treatments with nanosilver (NS, an ethylene action inhibitor) and ethephon (CEPA, an ethylene-releasing agent) influence petal color fading in 'Coral Sunset' peonies. Compared with the control (CK), CEPA pretreatment markedly increased the rate of ethylene production and reduced the anthocyanin content, a* value and C value of the petals. Concurrently, CEPA increased the levels of H 2 O 2 and MDA in the petals. CEPA downregulated the expression of anthocyanin biosynthesis-related genes ( PlCHSY and PlUAGT , PlbHLH3 ), and upregulated the expression of anthocyanin degradation-related genes ( PlPER4 and PlPER55 ). CEPA also affected the expression of genes associated with hormone signaling pathways, including those involving auxin, ethylene (ETH), jasmonic acid (JA), salicylic acid (SA), cytokinin (CTK), abscisic acid (ABA), and gibberellin (GA). Specifically, ETH and JA signaling-related genes were predominantly upregulated, whereas auxin-signaling-related genes were mainly downregulated. Metabolomic analysis indicated that CEPA primarily reduced the levels of peonidin, cyanidin, and pelargonidin glycosides in the petals. In contrast, NS delayed petal senescence and color fading, with most of its physiological effects being opposite to those of CEPA. Weighted gene co-expression network analysis (WGCNA) and protein-protein interaction (PPI) analysis suggested that the interplay between the ethylene- and JA-signaling pathways may play an important role in ethylene-signal perception and the regulation of anthocyanin biosynthesis. Collectively, color fading in ‘Coral Sunset’ petals resulted from the result of the synergistic effects of phytohormonal imbalance and oxidative stress. These findings provide new insights into the molecular mechanisms underlying phytohormone‑regulated petal color fading, and establish a theoretical framework for retarding color loss and formulating effective preservative solutions to improve the vase quality of cut peonies.