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Plant senescence is a complex process that is controlled by developmental regulation and genetic programs. A senescence-related gene <i>CpSRG1</i>, which belongs to the 2OG-Fe(II) dioxygenase superfamily, was characterized from wintersweet, and the phylogenetic relationship of CpSRG1 with homologs from other species was investigated. The expression analysis by qRT-PCR (quantitative real-time PCR) indicated that <i>CpSRG1</i> is abundant in flower organs, especially in petals and stamens, and the highest expression of <i>CpSRG1</i> was detected in stage 6 (withering period). The expression patterns of the <i>CpSRG1</i> gene were further confirmed in <i>CpSRG1pro::GUS</i> (<i>β-glucuronidase</i>) plants, and the activity of the <i>CpSRG1</i> promoter was enhanced by exogenous Eth (ethylene), SA (salicylic acid), and GA₃ (gibberellin). Heterologous overexpression of <i>CpSRG1</i> in <i>Arabidopsis</i> promoted growth and flowering, and delayed senescence. Moreover, the survival rates were significantly higher and the root lengths were significantly longer in the transgenic lines than in the wild-type plants, both under low nitrogen stress and GA₃ treatment. This indicated that the <i>CpSRG1</i> gene may promote the synthesis of assimilates in plants through the GA pathway, thereby improving growth and flowering, and delaying senescence in transgenic <i>Arabidopsis</i>. Our study has laid a satisfactory foundation for further analysis of senescence-related genes in wintersweet and wood plants. It also enriched our knowledge of the 2OG-Fe(II) dioxygenase superfamily, which plays a variety of important roles in plants.