Ethylene Response Factor OfERF16 Delays Postharvest Petal Senescence and Alters Floral Architecture in Osmanthus fragrans

In Osmanthus fragrans , the short postharvest life of individual flowers limits ornamental display and fragrance-related utilization, whereas the transcriptional regulators underlying petal senescence remain insufficiently defined. To clarify the role of OfERF16 , expression profiling was integrated with subcellular localization, transient overexpression in detached O. fragrans petals, stable overexpression in tobacco, physiological measurements, and interaction analyses. OfERF16 transcripts accumulated strongly at the late flowering stage, and the protein localized to the nucleus and cell periphery. OfERF16 overexpression delayed senescence in detached O. fragrans petals and in transgenic tobacco flowers. This response was accompanied by reduced expression of senescence-associated markers, lower malondialdehyde and H2O2 accumulation, and higher peroxidase activity and soluble protein content. In tobacco, OfERF16 overexpression also altered floral architecture, particularly by promoting stamen elongation relative to the pistil. Yeast two-hybrid screening identified candidate interactors, and bimolecular fluorescence complementation confirmed an in planta interaction between OfERF16 and the ABA-related transcription factor OfMYB306. Yeast one-hybrid and dual-luciferase assays showed that OfbHLH68 associates with the OfERF16 promoter and represses its transcriptional activity. These results place OfERF16 within a regulatory framework linking ethylene-responsive regulation, ABA-associated signaling, and redox homeostasis during postharvest petal aging, providing a mechanistic basis for improving floral longevity in O. fragrans .