The Functional Analysis Of EIF-5A And DHS And Application

DHS(Deoxyhypusine Synthase) is prevalent in plants,mammals and yeast cells,it participated in the post-translational activation of eIF-5A,eIF-5A is the only known substrate of DHS,the functions of them are inseparable.Lots of researches about DHS and eIF-5A in human being and yeast indicate that eIF-5A is involved in many cellular biological functions,especially correlates closely with both cell proliferation and cell senescence,but the exact functions remained unknown so far.According to the only a small number of studies in plants and our preliminary work,we found when the expression of DHS gene was depressed in Arabidopsis thaliana and Nicotiana tabacum,Plants show drought,cold and salinity-resistant features.So it is inferred that DHS and eIF-5A may be involved in regulation of plant senescence.This study attempted to verify the conjecture.We study the expression of DHS and eIF-5A in Arabidopsis,in order to investigate the biofunction of DHS and eIF-5A in plants.The study includes the identification of DHS and three eIF-5A mutants Arabidopsis.Isolate the promoters sequence of DHS and 3 eIF-5A from Arabidopsis,construct the expression cartier,whose the reporter gene GUS was inserted downstreaming these promoters.Preliminary exploration the biofunction of DHS and eIF-5A in plants.We also explored whether it can be a new way of genetically modifying plants by downregulating DHS gene expressional level.We have obtained several progress:1.Isolated the promoters sequence of DHS and 3 eIF-5A from Arabidopsis,constructed the expression carrier,whose the reporter gene GUS was inserted downstreaming these promoters.The expression carriers possessing promoters fused with GUS was transformed into wild-type Arabidopsis thaliana.And obtained the seeds of transgenic Arabidopsis plants.Lay the foundation for the study of the four genes' expression and mechanisms.2.Cultivated eIF-5A2 and eIF-5A3 mutants of Arabidopsis,by phenotype observation and PCR identification of them,Show that we have got the eIF-5A2 and eIF-5A3 mutant strains of Arabidopsis thaliana.Under normal growth conditions,there is no difference between the mutant and wild-type Arabidopsis thaliana.Under drought stress conditions, mutant exhibit lag bolting and obvious tolerance to drought stress,delay chlorophyll degradation.Show that eIF-5A gene is indeed closely related to cell senescence,may be a key protein of Cell senescence pathway.3.Our preliminary studies have already been obtained the antisense-DHS expression cartier,in this study,we transformed it into the poplar mediated by Agrobacterium.And we have already obtained 51 transgenic seedlings which were confirmed by using PCR. In order to explore the possibility and means of DHS in plant genetical modification,we treated the transgenic plants under drought,salt,leaf processing in vitro culture. Observated their changes in chlorophyll content.Comparing to the wild type plants,the DHS restricted ones grow better,with delayed in leaves senescing and tolerance against harsh environment and delayed chlorophyll degradation.