Cloning And Function Analysis Of MsHB7 Gene From Alfalfa

Plant growth and productivity are affected by various abiotic stress factors.Under drought and salt stress,plant growth and physiological function will be affected.Transcription factors play an important role in plant adaptation to the environment.Among them,the class I subfamily of hd-zip is mainly involved in the response of plants to abiotic stress.The purpose of this study was to clone the MsHB7 gene of class I subfamily gene of HD-Zip from alfalfa and study the function of this gene by transfering it into Arabidopsis thaliana and alfalfa.The main research results are as follows: 1.Cloning and bioinformatics analysis of MsHB7 geneThe MsHB7 gene from alfalfa was obtained by homologous cloning,which encodes 245 amino acids and contains two conserved domains: homeodomain and leucine zipper.Phylogenetic tree analysis showed that MsHB7 was a member of HD-Zip I transcription factor.2.Tissue specific expression of MsHB7 geneThe expression levels of MsHB7 gene in root,stem,leaf and flower tissues of alfalfa were detected.And it was found that MsHB7 gene was expressed in different tissues with the highest expression in flowers.3.Subcellular localization of MsHB7By constructing the subcellular localization vector of MsHB7 gene,MsHB7 gene and GFP protein were fused and expressed in tobacco cells.The results showed that MsHB7 protein was localized on the nucleus.4.Genetic transformation of MsHB7 gene to Arabidopsis thaliana and alfalfaThe plant overexpression vector p BI121-MsHB7 was constructed and transformed into Arabidopsis thaliana and alfalfa respectively.Transgenic positive plants were successfully obtained.5.Analysis of drought tolerance of Arabidopsis thaliana with MsHB7 geneTransgenic lines were wilted than WT plants,and the relative water content was lower after drought stress.Transgenic lines accumulated more proline and malondialdehyde under drought stress,which indicated that the transgenic lines were more sensitive to drought,suggesting that MsHB7 may negatively regulate Arabidopsis response to drought.qRT-PCR was used to further analyze the expression levels of ATCAT1,ATDREB2 A,ATLEA3 and ATRD29 A under drought stress.The results showed that the expression levels of ATCAT1,ATDREB2 A and ATRD29 A in transgenic plants were significantly higher than that of the wild type,while the expression levels of ATLEA3 were significantly lower than that of the wild type after treatment,indicating that MsHB7 gene may regulate the expression levels of these stress resistant genes,thus regulating the drought tolerance of plants.6.Salt tolerance of Arabidopsis thaliana with MsHB7 geneThere was no significant difference between transgenic lines and WT plants under salt stress,suggesting that MsHB7 gene was not involved in the response of Arabidopsis thaliana to salt stress.