Genome-Wide Characterization and Identification of Arf Gene Family Reveals the Regulation of RrARF5 in AsA Metabolism in<em> Rosa roxburghii</em> Tratt. Fruits

Rosa roxburghii Tratt., a fruit crop known for its high vitamin C content and other nutritional compounds, has not yet been studied for its Auxin Responsive Factor (ARF) gene family, which plays a crucial role in plant growth and fruit development. In the present study, we identified 14 ARF genes (designated as RrARFs) in R. roxburghii, which are distributed across seven chromosomes and grouped into four subfamilies. Cis-acting elements analyses revealed that these genes might be involved in various biological processes, including plant development, light responses, cell cycle regulation, phytohormone responses, and responses to abiotic and biotic stresses. Gene expression analysis demonstrated differential expression of RrARF genes across different tissues and stages of fruit development, with four members showing higher expression during the fruit ripening stages. Furthermore, coexpression analysis identified that RrARF5 was highly coexpressed with RrMDHAR1, a key enzyme involved in vitamin C biosynthesis. Moreover, transactivation assays and transient overexpression experiments confirmed that RrARF5 activates the transcription of RrMDHAR1. The outcomes of this study enhance our understanding of the ARF gene family&#039;s role in vitamin C accumulation in R. roxburghii and its broader impact on fruit quality regulation.