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| Cloning of DcDREB-A6 Group Transcription Factor Gene from Daucus carota L. and Its Analysis of Expression Profiles Under Abiotic Stress Treatments |
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Abstract In higher plant, dehydration responsive element-binding protein (DREB) family transcription factors play an important role under abiotic stress. Transcription factor binds specific DNA sequence to regulate related gene expression. DREB subfamily factors, one of the major subfamilies of the APETLA 2/ethylene responsive element binding protein (AP2/ERF) family transcription factor, were mainly divided into 6 groups, named A1 to A6 group. Carrot (Daucus carota L.), a biennial vegetable plant, is famous for its taproot and antioxidant compounds. In this study, the gene sequence, which encoded a DREB transcription factor of DcDREB-A6(GenBank accession No. KM386646), was isolated from carrot based on transcriptome and genome sequence data of carrot. The DcDREB-A6 gene was cloned by RT-PCR using cDNA as template from carrot cultivar Heitianwucun. Sequence analysis indicated that the length of DcDREB-A6 gene was 993 bp, which encoded 330 amino acids. Then, nucleic acid and deduced amino acid sequence, phylogenetic tree, and molecular modeling were further predicted and analyzed. It was predicted that the relative molecular mass of the DcDREB-A6 was 36.68 kD, and the pI was 6.00. The DcDREB-A6 was a hydrophilic protein. DcDREB-A6 from carrot was classified into A6 group of DREB subfamily transcription factor, which belonged to AP2/ERF family transcription factor. The sequence of DcDREB-A6 was highly conserved in the AP2 domain compared to the DREB transcription factors of other plants. The AP2 domain three-dimension structure of DcDREB-A6 of carrot was built with the template structure of 1gcc, which was the AP2 domain of the AtERF1 transcription factor. Protein three-dimensional structure prediction and analysis showed that the domain of DcDREB-A6 had typical structural features of AP2 domain, with one α-helix and three β-sheets. To elucidate the response of the DcDREB-A6 transcription factor gene of carrot to abiotic stresses (high temperature, low temperature, drought and high-salinity stresses), the gene was chosen for quantitative Real-time PCR experiment on Heitianwucun. Quantitative Real-time PCR analysis of the expression profiles showed that the DcDREB-A6 gene was induced by high temperature, low temperature, and high-salinity treatment, respectively. The DcDREB-A6 gene expression increased about 2 times by high temperature and low temperature after 4 and 2 h treatments in carrot, respectively. The DcDREB-A6 gene expression was induced about 4.6 times by salt stress treatments at 8 h treatment in carrot, and increased little by drought treatments in carrot. These results will be useful for elucidating the regulation roles of the DREB subfamily transcription factor under abiotic stress in carrot.
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Received: 24 March 2014
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