| TCP transcription factor is a kind of plant specific transcription factor,which is widely involved in the process of regulating plant growth and development.In this study,Betula platyphylla was used as the test material to analyze the tissue site expression specificity and hormone and abiotic stress response of TCP PCF subclass BpTCP1 and BpTCP2 genes and promoters,and to study the growth and development and drought and salt stress of overexpressed transgenic Betula platyphylla lines.The downstream target genes were identified by transcriptomics and yeast single hybridization.The results are as follows:1.Fluorescence quantitative PCR results showed that BpTCPl and BpTCP2 genes were up-regulated to different degrees in birch leaves,stem nodes,terminal buds,xylem and phloem.In the analysis of hormone and abiotic stress responses,the expression levels of BpTCPl and BpTCP2 showed corresponding changes.2.Plant expression vector of the BpTCP1 gene promoter was constructed by Infusion technology,and the predictive results of the PlantCARE software showed that the BpTCP1 gene promoter contained a number of components related to hormones,abbiotic stress and plant growth and development.GUS staining showed that the BpTCP1 gene was expressed in the leaves and terminal bud of the plant and was responsive to GA3,ABA and 4 abiotic stresses.It was further demonstrated that BpTCP1 gene plays a role in plant leaf development,hormone and abiotic stress response.3.Through Gateway technology,BpTCPl and BpTCP2 overexpression vectors were constructed,and agrobacterium-mediated genetic transformation of birch was carried out.Finally,7 TCP 1-overexpressed birch lines and 6 TCP2-overexpressed birch lines were obtained.Compared with the control lines,the seedling height,ground diameter,pitch spacing,leaf blade,chlorophyll content and endogenous hormone content of BpTCPl and BpTCP2 overexpressed birch lines all changed.4.Through salt tolerance and drought resistance tests,the indexes of salt damage and drought damage of transgenic lines and control lines were 66.7%and 63%respectively after 7d treatment,while the indexes of transgenic lines were all below 30%.The chlorophyll content and POD activity of transgenic lines were significantly higher than that of control lines during stress treatment,and the content of H2O2 and MDA were significantly lower than that of control lines.Processing as well as the stress of genetically modified strains of SOD and POD family control and has carried on the semi-quantitative analysis,the results show that the stress treatment after 7 d,controlled strain of SOD and POD gene expression of the mass were significantly decreased,while gm strains of SOD and POD gene expression is mainly presented with untreated express the trend of the flat or increases.5.Select the mature leaves of genetically modified(gm)and the control strain as a material for the transcriptome analysis,the results show that the BpTCPl and BpTCP2 differentially expressed genes expression and comparison between strain 2709 and 3565 respectively,and these differentially expressed genes in encoding transcription factors,are involved in cell proliferation and plant hormones were significantly enriched in the synthesis and signal transduction pathways.6.The expression levels of BpMYB8 and BpIAA5 genes were significantly increased in transgenic BpTCP1 and BpTCP2 birch transcriptome,and there were known TCP transcription factor binding elements on the BpMYB8 and BpIAA5 gene promoters.It was found that BpTCP1 regulated BpMYB8 by identifying GCCCR and GGACCA.BpTCP2 regulates BpMYB8 by identifying GCCCR,TAGGGCCT and GGACCA elements,and BpIAA5 by combining GCCCR elements. |
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