Using in silico and functional analyses, we cloned and validated the expression profile of an inducible soybean promoter (GmERF3) along with its novel wound-induced and delayed expression (WIDE) element. Promoters and their contributing promoter elements are the main regulators of gene expression at the transcriptional level. Although the Ethylene Response Factor (ERF) gene family is one of the most well-studied stress-responsive gene families in plants, their promoter regions have received little attention. In this study, we investigated the expression patterns driven by the soybean (Glycine max) GmERF3 promoter and its cis-acting elements in soybean and tobacco. Transcriptomic data revealed that the native GmERF3 gene was differentially expressed in organs and tissues of plants. In transgenic soybeans containing a 1.3 kb GmERF3 promoter fused to the green fluorescent protein (gfp) gene, organ- and tissue-specificity was observed in untreated plants while mechanical wounding led to induction of GFP expression. Further in silico and in planta analyses of the GmERF3 promoter sequence in soybean revealed different cis-acting elements, including a novel cis-acting element, which contributed to increased expression, 1-2 days after mechanical wounding. We have named this DNA motif the wound-induced and delayed expression element (GGATTCAAGTTTAACC). A synthetic promoter containing a tetrameric repeat of this element showed high but late wound-induced GFP expression in leaves of transgenic tobacco. Our study expands the toolbox of inducible promoters and promoter elements for potential use in basic and applied research.
Keywords: Ethylene Response Factor; GFP fluorescence; Induction; Promoters; cis-acting elements.