Analysis Of The Salt Tolerance Function Of The Transcription Factor PsnMYB108 Gene In Populus Simonii × P.nigra

MYB transcription factor family,as one of the largest transcription factor families in plants,affects the whole growth and development process of plants,and is very important in the response of plants to external stress.In this study,PsnMYB108 gene was selected from the salt tolerance genes screened from the former population of Populus simonii × p.nigra for gene function analysis.The results are as follows:A 954bp cDNA fragment of PsnMYB108 gene was cloned from the leaves of Populus simonii×P.nigra.The encoded protein contains 317 amino acids.It is an unstable hydrophilic protein,without signal peptide,transmembrane ability and has two conservative domains of MYB family.Phylogenetic tree showed that genetic distance of PsnMYB108 is closely related to MYB108 of Populus trichocarpa and MYB 108-like of OPopulus euphratica?Durio zibethinus?Camellia sinensis?Populus alba and Helianthus annuus.PsnMYB108 promoter contains cis acting elements related to plant stress resistance.Subcellular localization showed that PsnMYB108 protein was localized in the nucleus.The expression of PsnMYB108 gene is tissue-specific and induced by stress.The relative expression level of PsnMYB108 gene in roots was significantly higher than that in stems and leaves.Under salt stress,the expression of PsnMYB108 gene was up-regulated.It suggested that PsnMYB108 gene might be related to plant response to high salt stress.The ORF of PsnMYB108 gene was divided into 1-951 bp,1-315bp,316-951 bp,1-531bp,532-951bp,1-654bp,655-951bp,655-858bp and 859-951bp.The expression vector of pGBKT7-PsnMYB 108(different length)was constructed and transformed into yeast strain Y2H.The results showed that PsnMYB108 transcription factor had self activating activity,and the self activating domain was located in 99aa at the C end.The pROK?-PsnMYB108 plant expression vector was constructed to cultivate transgenic tobacco and analyze the physiological indexes of PsnMYB108 transgenic tobacco.The results showed that under salt stress,the germination rate of PsnMYB 108 transgenic tobacco seeds was higher than that of wild type,root length,SOD activity and POD activity of seedlings were significantly higher than that of wild type,MDA content and relative conductivity were lower than that of wild type.The results showed that PsnMYB 108 gene could enhance the antioxidant capacity,reduce the damage of tobacco cell membrane and improve the salt tolerance of tobacco.