Cloning, subcellular localization, and self-activation detection of two NAC transcription factors in responseto drought for Camellia oleifera

Drought stress is a major abiotic stress for the development, yield and quality of Camellia oleifera. NAC transcription factors are widely involved in drought and salt-stress induced signal transduction in plants. To explore the role of NAC transcription factors in the drought stress response of C. oleifera, two-year oil tea seedlings were used as materials. The CDS sequences of CoNAC5 and CoNAC79 were obtained from through TA cloning. Bioinformatics, subcellular localization and self-activation were performed. qRT-PCR was used to determine the tissue specificity of CoNAC5 and CoNAC79 gene expression and the expression PEG and ABA at different treatment times. The results were as follows:(1)Gene structure analysis showed that length of CoNAC5 and CoNAC79 were 1 044 bp and 990 bp, respectively, encoding 348 and 330 amino acids. Their theoretical isoelectric points were 8.86 and 8.57, respectively. The instability coefficients of the proteins were 41.35 and 37.47, respectively. No transmembrane domain was found between the two genes, the highest homology with persimmon and lychee, respectively. Subcellular localization showed that both CoNAC5 and CoNAC79 were located in the nucleus.(2)Yeast self-activation detection analysis revealed that CoNAC5 and CoNAC79 did not have self-activation activity in the full-length proteins and N-terminal domain. However, the C-terminal domain exhibited self-activating activity.(3)The expression of CoNAC5 and CoNAC79 had significant tissue specificity and mainly expressed in roots and kernels; when PEG simulated drought and exogenous ABA treated C. oleifera seedlings, the expression levels of CoNAC5 and CoNAC79 were significantly higher than the control; Furthermore, the expression level of CoNAC79 decreased after 48 h under ABA treatment, and significantly higher than the control under PEG treatment. In summary, it is believed that there may be an inhibitory region at the N-terminal of CoNAC5 and CoNAC79, which hinders the transcription of the full-length sequence; indicating that the two NAC genes in C. oleifera may be probably indirectly involved in drought stress response through pathway of ABA synthesis; CoNAC79 can also directly participate in the drought stress response through other pathways. This study provided a scientific basis for further exploring the role of NAC transcription factors in the response of C. oleifera to drought stress.