Genome-Wide Characterization of the C-repeat Binding Factor (CBF) Gene Family Involved in the Response to Abiotic Stresses in Tea Plant (Camellia sinensis)

C-repeat (CRT)/dehydration responsive element (DRE)-binding factor CBFs, a small family of genes encoding transcriptional activators, play important roles in plant cold tolerance. In this study, a comprehensive genome-wide analysis was carried out to identify and characterize the functional dynamics ofCsCBFsin tea plant (Camellia sinensis). A total of 6CBFgenes were obtained from the tea plant genome and namedCBF1-6. All of theCsCBFshad an AP2/ERF DNA-binding domain and nuclear localization signal (NLS) sequence. CsCBF-eGFP fusion and DAPI staining analysis confirmed the nuclear localization of the CsCBFs. Transactivation assays showed that the CsCBFs, except CsCBF1, had transcriptional activity. CsCBF expression was differentially induced by cold, heat, PEG, salinity, ABA, GA, MeJA, and SA stresses. In particular, theCsCBFgenes were significantly induced by cold treatments. To further characterize the functions ofCsCBFgenes, we overexpressed theCsCBF3gene inArabidopsis thalianaplants. The resulting transgenic plants showed increased cold tolerance compared with the wild-typeArabidopsisplant. The enhanced cold tolerance of the transgenic plants was potentially achieved through an ABA-independent pathway. This study will help to increase our understanding ofCsCBFgenes and their contributions to stress tolerance in tea plants.