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Functional Analysis Of A Tga Factor-binding Site Located In The Promoter Region Controlling Salicylic Acid-induced Nimin-1 Expression In Arabidopsis.

By J P Fonseca, M Menossi, F Thibaud-Nissen and C D Town


TGA factors play a key role in plant defense by binding to the promoter region of defense genes, inducing expression. Salicylic acid (SA) induces the expression of the gene encoding NIMIN-1, which interacts with NPR1/NIM1, a key regulator of systemic acquired resistance. We investigated whether the TGA2-binding motif TGACG located upstream of the NIMIN-1 gene is necessary for SA induction of NIMIN-1 expression. A mutated version of the NIMIN-1 promoter was created by site-directed mutagenesis. We generated T-DNA constructs in which native NIMIN-1 and mutated promoters were fused to green fluorescent protein and beta-glucuronidase reporters. We produced transgenic Arabidopsis plants and observed NIMIN-1 promoter-driven green fluorescent protein expression in the roots, petiole and leaves. Constructs were agroinfiltrated into the leaves for transient quantitative assays of gene expression. Using quantitative real-time RT-PCR, we characterized the normal gene response to SA and compared it to the response of the mutant version of the NIMIN-1 promoter. Both the native NIMIN-1 construct and an endogenous copy of NIMIN-1 were induced by SA. However, the mutated promoter construct was much less sensitive to SA than the native NIMIN-1 promoter, indicating that this TGA2-binding motif is directly involved in the modulation of SA-induced NIMIN-1 expression in Arabidopsis

Topics: Arabidopsis, Arabidopsis Proteins, Base Sequence, Basic-leucine Zipper Transcription Factors, Binding Sites, Carrier Proteins, Gene Expression Regulation, Plant, Green Fluorescent Proteins, Molecular Sequence Data, Mutation, Nuclear Proteins, Plants, Genetically Modified, Promoter Regions, Genetic, Protein Binding, Salicylic Acid
Year: 2015
DOI identifier: 10.4238/vol9-1gmr704
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