Cloning and Functional Analysis of three Cold Regulated CBF Genes in the Overwintering Crucifer Boechera stricta

In this research, we isolated three CBF (C-repeat-Binding Factors) genes from two genotypes of Boechera stricta with contrasting freezing tolerance and characterized their structure and expression patterns in response to cold treatment. An amino acid sequence comparison revealed that the CBF genes in B. stricta showed high conservation in the AP2 domain and PKKP/RAGR motif like other cold adaptable Brassicaceae. The pairwise sequence alignment of the CBF genes isolated from two genotypes of B. stricta showed non-synonymous mutations in CBF 2 and 3. Gene expression analysis demonstrated that CBF genes in B. stricta have expression patterns similar to CBFs in A. thaliana in response to cold treatment, while differential expression at the molecular level in CBF and COR genes was presented between two genotypes of B. stricta. Our results suggest that signal transduction of three CBF genes can be one of the central pathways in the development of freezing tolerance in B. stricta.