Cloning， expression and trans-activation activity analysis of DcNAC1 gene from Dendrobium catenatum

【Objective】 This study was to dissect the expression pattern and trans-activation activity of the NAC gene （DcNAC1）of Dendrobium catenatum， thus providing a foundation for stress-related genes identification and elucidating the molecular mechanism of D. catenatum stress-resistance.【Method】 DcNAC1 gene was amplified by PCR using D. catenatum cDNA as template. The physical and chemical properties，conserved domain，signal peptide，transmembrane domain and subcellular location of DcNAC1 protein were analyzed by bioinformatics softwares. The expression patterns of DcNAC1 gene in different tissues and under different stresses were detected by real-time fluorescence quantitative PCR. At the same time，yeast expression vector of this gene was constructed and its transcriptional self-activation activity was analyzed.【Result】 The open reading frame（ORF）of DcNAC1 gene was obtained by PCR amplification from D. catenatum. The total length was 945 bp，and the nucleotide sequence similarity to the reference sequence（LOC110104882）was 100%. This gene encoded 314 amino acid residues，had a molecular weight of 35.40 kD and a theoretical isoelectric point （pI）of 8.16. It was an unstable hydrophilic protein，localized in the nucleus，free of signal peptides and transmembrane domains，and contained a characteristic NAC conserved domain. The promoter sequences of DcNAC1 gene included jalapic acid response elements（CGTCA-motif and TGACG-motif），stress response elements（TC-rich repeats），light response elements（G-box），drought-induced MYB binding sites（MBS）and low temperature response elements（LTR）. The relative expression of DcNAC1 gene in root reached the highest level at 6 h under high temperature stress and low temperature stress，respectively，and was significantly higher than that at 0 h under high temperature stress（P＜0.05，the same below）. The relative expression of DcNAC1 gene in stems was the highest at 48 h after salt stress treatment，which was significantly higher than that at 0 h. The recombinant plasmid pGBKT7-DcNAC1 was transformed into yeast strain Y2HGold. The results showed that the recombinant plasmid was not toxic，but DcNAC1 protein had certain self-activation activity.【Conclusion】DcNAC1 gene expression is regulated by jasmonic acid，low temperature，drought，light signal and stress. DcNAC1 protein has self-activating activity，which is involved in transcriptional regulation of plant growth and development and response to stress by activating the expression of downstream genes.