Cloning Of Promoters And Transcription Factor Characteristic Analysis Of HaNAC38 And HaNAC42 From Haloxylon Ammondendron

Haloxylon ammodendron is a kind of desert zonal shrub or dungarunga,it has salt tolerance,drought tolerance,and sand fixation functions,plays an important role in the management and maintenance of desert ecosystem.NAC transcription factors are ubiquitous in higher terrestrial plants.In this study,the data of drought and high temperature in the earlier transcriptome of group were used,and 64 full-length NAC genes were spliced.After number for these,we found that the expression level of HaNAC38 and HaNAC42 was significantly higher than that of other NAC genes when they under stressless.After drought and high temperature stress,the expression level increased significantly.Quantitative fluorescence analysis showed that HaNAC38 and HaNAC42 genes were up-regulated after simulated drought stress,simulated high surface temperature or high salt stress.So we can speculate that HaNAC38 and HaNAC42 genes play an important role in the normal growth and development of Haloxylon ammodendron and response to stress.This article also further analyzed the expression patterns and functions of HaNAC38 and HaNAC42.Following are the results:In this article,the promoters of HaNAC38 and HaNAC42 whose length is 1681 bp and 1200 bp were cloned by chromosome walking method,and the elements of it's sequence were analyzed.The results showed that both HaNAC38 and HaNAC42 contained partial stress response elements,at the same time,when compared with the promoters of the HaNAC2 and HaNAC3 genes that have been cloned in the earlier period of this research,HaNAC38 contained the element 5 UTR Py-rich stretch with a high level of transcription,while the number of HaNAC42 promoter TATA-boxes in the transcribed region was nearly 40,which is more higher than HaNAC2 promoter and HaNAC3 promoter,as they are only 14 or 22.This may be the reason for the high expression level of HaNAC38 and HaNAC42 genes under normal conditions.Transient transformation of tobacco leaves indicated that this promoter can regulate GUS gene expression.This study used yeast one-hybrid technique to verify the transcriptional autoactivation activity of HaNAC38 and HaNAC42 transcription factors.The resultsshowed that HaNAC38 protein has transcriptional self-activation activity,and the transcription activation domain is located at the protein's C-terminus.The HaNAC42 transcription factor does not have transcriptional self-activation activity,we presumably it may regulate downstream gene expression through interacting with other proteins.Subcellular localization analysis of HaNAC38 and HaNAC42 transcription factors was performed and the green fluorescence was observed after the tobacco epidermis transfection by Agrobacterium-mediated injection.The results showed that HaNAC38 and HaNAC42 were localized in the nucleus.In order to study the binding activity of NAC protein and obtain highly expressed HaNAC38 and HaNAC42 proteins,prokaryotic expression vectors were successfully constructed and induced.In order to research the function of HaNAC38 accurately,the plant expression vector pCAMBIA1304-HaNAC38 was constructed,and impregnation method used to transform Arabidopsis thaliana to obtain T₁ seeds,which laid a foundation for subsequent experiments.