Abstract
Promoters are very important for transcriptional regulation and gene expression, and have become invaluable tools for genetic engineering. Owing to the characteristics of obligate biotrophs, molecular research into obligate biotrophic fungi is seriously lagging behind, and very few of their endogenous promoters have been developed. In this study, a WY7 fragment was predicted in the genome of Oidium heveae Steinmann using PromoterScan. Its promoter function was verified with transient transformations (Agrobacterium tumefaciens-mediated transformation, ATMT) in Nicotiana tabacum cv. Xanthi nc. The analysis of the transcription range showed that WY7 could regulate GUS expression in both monocots (Zea mays Linn and Oryza sativa L. spp. Japonica cv. Nipponbare) and dicots (N. tabacum and Hylocereus undulates Britt). The results of the quantitative detection showed that the GUS transient expression levels when regulated by WY7 was more than 11.7 times that of the CaMV 35S promoter in dicots (N. tabacum) and 5.13 times that of the ACT1 promoter in monocots (O. sativa). GUS staining was not detected in the T1 generation of the WY7-GUS transgenic N. tabacum. This showed that WY7 is an inducible promoter. The cis elements of WY7 were predicted using PlantCARE, and further experiments indicated that WY7 was a low temperature- and salt-inducible promoter. Soluble proteins produced by WY7-hpa1Xoo transgenic tobacco elicited hypersensitive responses (HR) in N. tabacum leaves. N. tabacum transformed with pBI121-WY7-hpa1Xoo exhibited enhanced resistance to the tobacco mosaic virus (TMV). The WY7 promoter has a lot of potential as a tool for plant genetic engineering. Further in-depth studies will help to better understand the transcriptional regulation mechanisms of O. heveae.
Highlights
Gene expression is largely regulated by promoters, making them important tools in genetic engineering
In studying the manner in which WY7 regulated the expression range and level of exogenous genes in plants, we discovered that it had the potential to be an excellent promoter for use in genetic engineering
No homologous sequence aligning with WY7 was found in the National Center for Biotechnology Information (NCBI) database or in the eukaryotic promoter database (EPD)
Summary
Gene expression is largely regulated by promoters, making them important tools in genetic engineering. Constitutive expression, inducible expression, time-specific expression, and space-specific expression of exogenous genes in transgenic hosts are all foci of gene expression research. Furthering these research directions urgently requires more varieties promoters to be developed and applied, especially with regard to genetically modified crops required for human food-security and wellbeing. One example is the constitutive gpdA promoter in Aspergillus nidulans [1]. Another is the inducible cbh promoter that is induced by lactose, cellulose, and cellobiose, which is mainly used to express heterologous genes in Trichoderma reesei [2]. The ethanol-inducible promoter alcA in Aspergillus nidulans has been used in a wide range of studies on objective genes [3]
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