| PMADS20gene of Petunia is a member of STMADS11subfamily. MADS-box gene is a class of transcription factors, which are widely presented in animals, plants and fungi. A series of gene transcription, when transcribed, and the frequency of transcription are regulated at the transcriptional level. Different tissue or organ of living organisms, and its various periods growth and development always go with the expression of transcription factor gene. STMADS11subfamily gene function is to control the various periods of development of the vegetative organs and decided to vegetative growth to reproductive growth shift in space and time. By analyzing the sequence of gene of PMADS20and STMADS11subfamily members, that PMADS20gene may play a role in Petunia bud formation, thus contributing to the petunia transition to reproductive growth.Transcription factor, also known as trans-acting factors and the promoter specific DNA sequences of cis-acting elements to recognize each other, combined with precise regulation of gene transcription start and transcription efficiency, which directly or indirectly[1]. Transcription factor according to its transcriptional regulation ability can be divided into activator of transcription and transcriptional repressor. The transcriptional repressor, is divided into active and passive inhibition of transcription factor under the type of transcriptional repressor protein and the mode of action. Secondly, transcription factors can be divided into MYB class again, bHLH class bZIP class zinc finger classes and AP2/EREBP classes by the way of binding to DNA. Plant active restraining factor can also be classified according to its repression domain. At present, the research of plant transcriptional repressor is not still perfect. For example, EAR domain is a repression domain, containing only12amino acids, act as dominant repressors in transgenic Arabidopsis and suppress the expression of specific target genes, even in the presence of the redundant transcription factors, with resultant dominant loss-of-function phenotypes. Repression domain is the center of the regulation mechanism of a transcriptional repressor and related gene expression[2].Type transcription factor with a different EAR structure together and can suppress the expression of target genes. Therefore, chimeric repressor gene-silencing technology.(CRES-T) to become one of the new gene silencing technology.First, using PCR method to get the gene coding region (GenBank: GU129907) of PMADS20gene from the cDNA of petunias blade in this experiment. Second, using bioinformatics software analysis found that PMADS20gene have high homology to Arabidopsis of SVP gene and AGL24gene which belongs to STMADS11subfamily of MADS-box gene family.Third, the result of fluorescence quantitative analysis showed that PMADS20gene expression in the roots, stems, leaves, especially expressed in the axillary buds. Finally, building PMADS20gene plant over-expression vector PG503and gene fusion silence vector PG504which using the chimeric repressor gene-silencing technology (CRES-T). Agrobacterium transformation import the PMADS20gene into petunia leaves, in the screening medium which induces the formation of callus, and then filter out the seedlings containing the target gene and herbicide-resistant marker gene, at the last positive transgenic plants were grow up. Now, we have been identified35transgenic lines from PG503and PG504, respectively. Compared with wild-type PG503transgenic plants have no obvious phenotype, but the PG504transgenic plants get changes in plant morphology significantly,such as decreased plant height, dense branch, shortened internodes, narrow leaves, delayed flowering time.It’s supposed than there are some functional redundancy gene,at the downstream,which regulate the life activities of plant Currently, PMADS20gene function analysis and verification achieved some success, has an important significance for further understand PMADS20gene expression and regulation characteristics. |
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