Function Analysis Of ThTrx5 Gene From T. Androssowii Under Salt Resistance

Thioredoxin(Trx),a acidic protein with thermal stability,involves in responding for drought,oxidation,heat and other stress.It involves in signal transduction,also has an impact on starch synthesis metabolism,seed germination and seedling growth.In this study,nine Trx genes were cloned from Tamarix hispid,the temporal expression patterns of ThTrx genes under different stress treatments were analysed using real-time quantitative PCR.ThTrx5 gene was screened and transformed into Arabidopsis thaliana.The salttolerance of transgenic lines were evaluated by measuring the salt injury index,seedling fresh weight and the content of oxidized glutathione under salt stress.Downstream regulatory genes and interacting proteins of ThTrx5 were studied by transcriptome and Pull down technology,The results are as follows:Through the analysis of bioinformatics,we found that the amino acid sequences in C?terminal of ThTrx genes were highly conserved,andcontained highly conserved WCGPC,which was disulfide activity center of thioredoxin,two Cys residue can catalyze many redox reaction reversibly.However,N-terminal sequences were very different.ThTrx5 gene was located in the chloroplast,which encoded 233 amino acids and belonged to the Chloroplastic Trx subfamily.Using real-time quantitative PCR,we found that the expression levels of nine genes were changed under NaCI,CdCl2 PEG6000,low temperature and ABA stress.It illustrated that ThTrx exhibited different responses under different stresses,and ThTrx5 genes were up-regulated in most treatments.Compared with the overexpression of ThTrx5 in Arabidopsis and wild type plants under salt stress,we found that salt tolerance of transgenic lines was obviously higher than that of wild type,and the content of GSSG was higher than the control.It suggested that ThTrx5 gene can improve the ability of salt tolerance to some extent.Screening ThTrx5 interacting proteins using His Pull-down technology,we obtained five proteins,which may interact with ThTrx5.They were Catalase,CYP20,ATP synthase subunit beta,2-Cys peroxiredoxin and GAPDH,respectively.Using high-throughput Solexa sequencing technology,we established the untreated and salt stress treatment 3 h of wild types and ThTrx5 overexpression lines.The results showed that between the untreated wild type and transgenic ThTrx5,ThTrx5 overexpression lineshad 500 differentially expressed genes.Among them,the expression levels of 115 genes were up-regulated,the expression levels of 385 genes were down,regulated;After salt stress,the number of differentially expressed genes was 194 in the ThTrx5 transgenic lines,of which 66 genes were up-regulated,128 genes were down-regulated.The superoxide dismutase(SOD),peroxidase(POD),glutaredoxin(Grx)and calmodulin,were all high abundance expression in ThTrx5 overpression lines.It showed that ThTrx5 regulated the expression of these genes to improve the salt resistance of plant under salt stress.