C2H2 Zinc Finger Protein Family Analysis of Rosa rugosa Identified a Salt-Tolerance Regulator, RrC2H2-8

<i>Rosa rugosa</i> is a representative aromatic species. Wild roses are known for their strong tolerance to highly salty environments, whereas cultivated varieties of roses exhibit lower salt stress tolerance, limiting their development and industrial expansion. Previous studies have shown that C2H2-type zinc finger proteins play a crucial role in plants' resistance to abiotic stresses. In this study, 102 C2H2-type zinc finger genes (<i>RrC2H2s</i>) were identified in <i>R. rugosa</i> via a comprehensive approach. These genes were categorized into three lineages, and their motif constitutions were grouped into four classes. <i>RrC2H2s</i> were distributed across all seven rose chromosomes, with 15 paralogous gene pairs identified within synteny regions. Additionally, 43 <i>RrC2H2s</i> showed differential expression across various tissues under salt stress, with <i>RrC2H2-8</i> being the only gene consistently repressed in all tissues. Subcellular localization analysis revealed that the RrC2H2-8 protein was localized in the nucleus. The heterologous expression of <i>RrC2H2-8</i> in <i>Arabidopsis</i> significantly improved its growth under salt stress compared to the wild-type (WT) plants. Furthermore, the malondialdehyde content in the roots of transgenic <i>Arabidopsis</i> was significantly lower than that in the WT, suggesting that <i>RrC2H2-8</i> enhanced salt tolerance by reducing cellular damage. This study provides a systematic understanding of the <i>RrC2H2</i> family and identifies <i>RrC2H2-8</i> as a regulator of salt tolerance, laying a foundation for future research on the mechanisms of salt stress regulation by <i>RrC2H2</i>.