| Summary: | C-repeat binding factors/dehydration responsive element binding factors 1 (CBFs/DREB1s) are a small family of transcription factors that play important roles in plant resistance to various external stresses. However, functional characterization of tea plant (<i>Camellia sinensis</i> L.) <i>CBF</i> gene (<i>CsCBF</i>) was still seldom reported. Here, functional study of the cold-responsive <i>CBF</i> gene (<i>CsCBF2</i>) was done. Results showed that CsCBF2 had conserved AP2 DNA-binding domain and the typical PKK/RPAGRxKFxETRHP and DSAWR signature sequences of CBF/DREB1. Yeast one-hybrid and transcription activation assays revealed that the activation domain of CsCBF2 could activate the reporter gene expression, and the N terminal of CsCBF2 displayed an inhibitory effect. Although CsCBF2 was conserved to bind the C-repeat/dehydration-responsive element (CRT/DRE), intact CsCBF2 protein preferred the CRT <i>cis</i> element. Under normal growth conditions, <i>CsCBF2</i>-overexpressing tobacco plants (<i>CsCBF2</i>-OX) exhibited lighter green leaf color, growth retardation, and dwarfism. Smaller leaf of <i>CsCBF2</i>-OX was only seen in eight weeks after been sown in soil. Under cold, salinity, or drought stress, <i>CsCBF2</i>-OX displayed better growing with longer roots, heavier fresh weight, higher germination rate, and accumulated more proline and sugar contents, but lower electrolyte leakage. The results demonstrated that <i>CsCBF2</i> enhanced plant tolerance to multiple abiotic stresses.
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