Functional Analysis Of Salt Stress Tolerance Of Populus Simonii X P.nigra MYB122 Gene

The MYB transcription factor family is one of the most diverse and numerous families in the plant kingdom,and it plays an important role in stress tolerance,development,and signal transduction in plants.Previous studies indicated that the expression of MYB122 gene was induced by salt stress.Therefore,this study was focus on the salt tolerance function of PsnMYB122 gene.The results are as follows:the CDS of Populus trichocarpa MYB122 gene was obtained from the PlantTFDB online website,and a pair of specific primer was designed.The 951 bp CDS sequence of PsnMYB122 gene was cloned.from Populus simonii x P.nigra Bioinformatics analysis revealed that The protein contains 317 amino acids and has a molecular weight of 36.4 kDa.It is a hydrophilic protein.RT-qPCR analysis showed that the expression of PsnMYB122 gene was induced by salt stress with tissue-specific.Under 150 mM NaCl stress,the expression level of the gene in roots was significantly higher than that in leaves and stems,and the expression level reached the highest at 12h.The PsnMYB122 gene was conducted into the pBI121-GFP vector for subcellular localization,results showed that the PsnMYB122 protein was localized in the nucleus.The pGBKT7-PsnMYB122 vector was constructed for yeast two-hybrid experiments.Results indicated that PsnMYB122 has transcriptional self-activating activity,and its transcriptional activation domain is located the C-terminal 1-60aa.The pGADT7-Rec-PsnMYB122 vector and pAbAi-target promoter bait vector were constructed,and yeast one-hybrid experiments determined that the PsnMYB122 protein could bound to the W-box element.The pBI121-PsnMYB122 plant expression vector was constructed and the transgenic tobacco was obtained by Agrobacterium-mediated leaf disc transformation method.Under 150 mM NaCl stress,the transgenic tobacco showed significantly higher salt tolerance than that of wild type.The germination rate,root length and growth status of transgenic tobacco showed obvious advantages over the control.The POD,SOD activity was higher than that of wild-type tobacco,while MDA content was lower than that of wild-type tobacco.DAB,NBT and Eavns blue histochemical staining results showed that transgenic tobacco was lighter than wild type under salt stress.The results mentioned above indicate that PsnMYB122 gene can improve the salt tolerance of plants.