Functional Analysis Of PsnHSF21 Gene From Populus Simonii×P.nigra In Salt Stress Tolerance

Plants are affected by many external factors during their growth,among which salt stress is the main abiotic stress affecting plant growth.Heat shock transcription factor（HSF）is an important family of transcription factors that regulate plant stress response and play an important role in plant growth and development and response to salt stress network.In this study,poplar HSF family genes were selected as research objects to analyze their expression patterns and biological functions under salt stress.The specific results are as follows:1.Thirty members of poplar HSF family were identified,which could be divided into A,B and C subfamilies.The members of the same subfamily shared relatively conserved domains and motifs,and had high homology.Poplar HSF family proteins are all acidic and hydrophilic proteins,which are located in the nucleus.Their gene expansion is mainly realized through segicular replication,and they have rich collinearity across species.The promoter sequence of poplar HSF family gene contains not only the core elements of promoter,but also many elements that regulate growth and development,abiotic stress response elements and hormone response elements.2.The c DNA fragment of PsnHSF21 gene induced by salt stress was cloned.Its coding region length was 636 bp,encoding 211 amino acids and possessing the conformation domain of the HSF-DNA-bind family.The expression of PsnHSF21 gene was tissue specific and induced by salt stress.Subcellular localization showed that PsnHSF21 was localized in the nucleus.3.PsnHSF21 gene overexpression vector was constructed,and PsnHSF21 gene overexpression transgenic Populus simonii×P.nigra was obtained by agrobacterium-mediated method.Under 200 m M Na Cl stress,the growth state of transgenic poplar was better than that of wild type,and its POD activity,chlorophyll content and proline content were higher than those of wild type,while its H₂O₂ activity,MDA content,relative conductivity and water loss rate were lower than those of wild type.4.The yeast experiment showed that PsnHSF21 had transcriptional autoactivation activity,and the transcriptional activation region was 62 aa at the C-terminal.PsnHSF21 protein can bind specifically to the anti-stress element HSE.In conclusion,this study comprehensively analyzed the basic information and salt damage response of poplar HSF family members,specifically analyzed the salt resistance function of PsnHSF21,and preliminarily explored the salt stress response network of PsnHSF21,providing clues for in-depth understanding of the molecular mechanism of stress resistance of poplar HSF members.