Study on the Mechanism of CaMV 35S Enhancer Regulating Gene Expression in Maize (Zea mays)
GUO Jin-Jie1, ZHANG Dan1, ZHANG Wei1, ZHANG Fang-Dong1*, DU Deng-Xiang2*
1 Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; 2 School of Biological and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China
Abstract：Maize (Zea mays) is an important food crop, feed source and industrial raw material. With the development of bio-technology, transgenic and other new technologies are widely used in maize breeding. Cauliflower mosaic virus 35S (CaMV 35S) promoter and its enhancer are widely used in transgenic operation of maize and other crops. Therefore, studying the mechanism of CaMV 35S enhancer has important theoretical value for future application. Two trait mutants were screened from a maize activation-tagging mutant library previously constructed by the research group on genetic improvement of maize. Based on the identification of artificial transposon insertion sites in the chromosomes, the spatio-temporal variation of gene RNA expression in the range of about 100 kb upstream and downstream of the transposon insertion sites was analyzed using qPCR. The results showed that the enhancer of CaMV 35S significantly up-regulated the gene expression of adjacent genes (P<0.05), and the transcriptionally increased genes were distributed upstream and downstream of the transposon insertion site, with activation distance of up to 63.7 kb. Of the 4 genes up-regulated expression, the enhancement was dose-dependent, and the expression of the homozygous mutant was significantly higher than that of the heterozygous mutant (P<0.05). Although the CaMV 35S enhancer increased the transcription level of genes in the maize mutants, it did not significantly change the expression pattern of genes in different tissues. The scope, dosage effect, and tissue specificity of CaMV 35S enhancer in maize provide an experimental basis for subsequent use in maize molecular biology, and genetic engineering, and can also provide reference for the application of the promoter in other plants.
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