Functional Analysis Of Populus Alba × Populus Glandulosa Transcription Factor NAC57 Gene In Salt-stress Tolerance

The NAC transcription factor family is a plant-specific transcription factor family,which have a highly conserved DNA-binding domain composited with about 150 amino acid in the N-terminal.NAC transcription factor genes pay an important roles in plant growth and development,it was known that NAC transcription factor gene was involved in plant minerals and nutrients in the transport of nutrients,hormone regulation and signal transduction related to the plant secondary growth process,the formation of the top meristem,the establishment of organ boundaries,cell division,plant senescence,response to stress and other processes.In the present study,12 NAC genes were detected by transcriptome sequencing and RTqPCR,10 genes were up-regulated and 2 genes were down-regulated.Tissue specificity analysis of NAC57 gene(Potri.005G205400.1)showed that the NAC57 gene was expressed wih the highest expression level in fibrous roots and primary leaves.The specific expression level of NAC57 under salt stress was analyzed.It was found that the relative expression level of NAC57 gene was increasing from 0 h to 24 h after salt stress,and reached its peak at 24 h,then decreased.The NAC57 promoter was cloned and sequenced.The cis-acting elements in promoter were predicted by softwre.The expression vector of GUS gene drived by NAC57 promoter was constructed.Transient infection and GUS staining showed that the GUS driven by NAC57 promoter was expressed in leaves and roots of Arabidopsis thaliana seedlings,but almost none of the stems.The cDNA fragment of NAC57 gene was cloned and analyzed by bioinformatics,and NAC57-GFP recombinant vector.was constructed.The expression of NAC57 was detected in the cytoplasm of the onion epidermis by transient expression.NAC57 gene expression vector was constructed and transformated into Arabidopsis thaliana by immersion method.the transgenic plants of NAC57 gene were obtained.The analysis of stress resistance and physiological index showed that the transgenic Arabidopsis overexpressing NAC57 gene have a significant stronger salt-tolerant ability.