Coloning And Functional Analysis Of Three Salt Tolerance Genes In Populus Euphratica

Populus euphratica,a only forest species in the desert region of northwest China,has a strong resistance to salt,drought,extreme temperatures,etc.Thus,it has been considered as a candidate model tree species for the study of mechanism of stress resistance.So salt tolerance genes study of P.euphratica is important for reveal salt resistance molecular mechanism of trees.Among them,F-box protein can specifically identify the substrate protein in the ubiquitin-proteasome pathway and regulate the signal transduction pathways of hormones.Moreover,F-box gene responses to a variety of abiotic stresses and involved stress-tolerant pathway in plants.CDPK gene,as an important second messenger in plant signal transduction pathways,almost mediated plant growth and development,and response to adversity reaction.In this study,the gene cloning,expression characteristics analysis,subcellular localization and salt resistance analysis of genes that obtained by associated analysis for salt-tolerance traits of P.euphratica were performed to search its function characteristics.All of these mechanisms provide new insignts into the salt tolerance of plants.Main results for this study are as follows:CDPK gene of P.euphratica contains 822 nucleotides,which code 273 amino acids.The results of qRT-PCR showed that CDPK gene was expressed in various tissues,without tissue specificity.Its expression was induced by the salt,high temperature,low temperature,drought,and ABA stresses.GUS histochemical assay was used for CDPK expression pattern analysis,CDPK promoter was intensively expressed in leaf vein,hypocotyl-root junction and primary root tip for the two weeks of seedlings.Transient expressing of P.euphratica protoplast mediated by PEG showed CDPK protein was located in cytoplasm and nucleus.Seed germination of Arabidopsis confirmed that over expression of CDPK gene enhanced the salt resistance of seeds.F-box gene of P.euphratica contains 1086 nucleotides,which code 361 amino acids containing F-box domain and F-box associated domain.The results of qRT-PCR showed that F-box gene was expressed in various tissues,without tissue specificity.Its expression was induced by the salt,high temperature,low temperature,drought,and ABA stresses.Transient expressing of P.euphratica protoplast mediated by PEG showed F-box protein was located in nucleus,and it enhanced the salt resistance of protoplast.Unknown gene of P.euphratica contains 519 nucleotides,which code 172 amino acids.The results of qRT-PCR showed that unknown gene was expressed in various tissues,without tissue specificity.Its expression was induced by the salt,high temperature,low temperature,drought,and ABA stresses.Transient expressing of P.euphratica protoplast mediated by PEG showed unknown protein was located in cytoplasm.Seed germination of Arabidopsis confirmed that over expression of unknown gene enhanced the salt resistance of seeds.The preliminary results of this study reveal the expression characteristics and salt resistance of CDPK gene,F-box gene and unknown gene from P.euphratica,and provide a reference for further analysis of genes function and molecular mechanism with resistance to stress in P.euphratica.