Genome-wide Analysis Of The HSP70Superfamily In Gossypium Raimondii And Functional Study Of GhHSP70-20

Cotton fiber is one of the most important textile materials on the world, plays an important rolein our national economy. Members of the heat shock protein70(HSP70) class of proteins areevolutionarily conserved molecular chaperones. They are involved in protein proper folding, both inunstressed as well as stressed conditions. They are also widely involved in plant growth anddevelopment process. This study provides rich information of the cotton HSP70gene family whichlays the foundation for future efforts to study the molecular mechanism of fiber development. Themain work included the followings:1) In this research, a comprehensive evolutionary and expression analysis of the Gossypiumraimondii HSP70gene family were conducted and30HSP70genes are predicted and identified. Thedetailed gene structure, chromosome distribution and phylogenic evolution were further analyzed.The results show that HSP70family genes can be clustered into several major subgroups based on thesubcellular location prediction results. The gene structure and motif composition and arrangementsare relatively conserved in each subgroup. The expression profiles of HSP70revealed that manyHSP70genes in cotton may participate in fiber development process including fiber initiation andelongation.2) The CDS sequence of GhHSP70-20was cloned with the help of bioinformatics methods.Inorder to investigate the subcellular localization of GhHSP70-20,GhHSP70-20::eGFP fusionexpression vector was constructed and introduced into onion inner epidermal cells by particlebombardment.Green fluorescence was observed in the cytoplasm.3) The results of RT-PCR indicated that the expression level of GhHSP70-20can be inducedunder thermal stress. The expression of GhHSP70-20in fibers and ovules exhibit a developmentallyregulated pattern,and its transcripts reached the highest levels in the elongation stage of fiberdevelopment.In addition,the expression levels of GhHSP70-20were higher in wild type than in Li-1mutant.4) Overexpression and antisense expression vectors of GhHSP70-20were constructed andintroduced into Arabidopsis thaliana,and T2generation of transgenic plants were obtained. Theanti-GhHSP70-20transgentic plants lines were more sensitive to salt stress and ABA compared withthe wild type.5) We cloned the promoter sequence of GhHSP70-20and analysis the cis-ating elements of thepromoter region.A fusion vector containing the GhHSP70-20promoter connected to the GUS genewas introduce into Arabidopsis plants. GUS histochemical staining analysis of transgenic plantsshowed that the promoter was active in the leaf vein and silique.