Functional analysis of CsCBF3 transcription factor in tea plant (Camellia sinensis) under cold stress

C-repeat binding factors (CBFs) are involved in multiple pathways of plant growth, development and stress responses. In this study, CsCBF3, a gene encoding a polypeptide of 274 amino acids and containing the structural feature of AP2 domain in CBF protein family, was characterized from tea plant [Camellia sinensis (L.) O. Kuntze]. CsCBF3 was located in cell nucleus and cytoplasm by subcellular localization analysis. Expression analysis revealed that CsCBF3 was induced by low temperature stress, abscisic acid and drought treatment in tea leaves. CsCBF3 overexpressed Arabidopsis displayed higher tolerance to cold stress and improved photosynthesis ability with less damage under cold condition compared to wild type plants. Furthermore, it was observed that the CsCBF3 gene regulates the expressions of downstream genes of cold responsive pathway, such as AtCOR15a and AtCOR78. These results indicate that CsCBF3 plays an important role in responding to cold stress and provide potential applications in molecular breeding to enhance cold tolerance in tea plant.