Abstract:

CBF transcription factors play a central role in controlling freezing tolerance in plants. A novel CBF/DREB1 gene was isolated, from Corylus heterophylla, one of the cold-hardiest Corylus species, named as ChCBF. Sequence analysis revealed that ChCBF had 1 053 bp in full length and contained an open reading frame (ORF) of 684 bp encoding a 227 predicted amino acids residues which possessed conserved AP2/EREBP domain for the CBF function. Sequence alignment and phylogenetic analysis revealed that conserved domain of ChCBF shared high identity with CBF homologues from other plant species in all conserved regions. Expression profiling of ChCBF was performed by qRT-PCR method, ChCBF transcripts were highest at the stage of cold acclimation (CA), while the level of ChCBF was down-regulated during the coldest mid-winter (MW), and increased again as buds deacclimated (DA). ChCBF transcripts were rapidly and highly induced when plants were exposed to low temperatures of 4 ℃, and ChCBF was activated in 4 h reaching a peak, suggesting that the critical transcriptional changes of ChCBF occurred majorly during the initial 4 hours and it was possibly involved in early-stage responses to low temperature. Spatial expression analyses revealed that the transcription level of ChCBF was relatively higher in bud than that in male inflorescence and bark tissues. These results suggest that ChCBF may participate in the cold acclimation process and show temporal-spatial specific expression characteristics in hazelnut.

Key words: Corylus heterophylla, CBF, qRT-PCR, temporal-spatial expression