TMEK2MUT is a constitutively activated form of tMEK2, a mitogen-activated protein kinase kinase (MAPKK). Overexpression of tMEK2MUT in tomato results in transcriptionally upregulated expression of PR1b1, a pathogenesis-related (PR) protein. To identify the responsive regions in the lepr1b1 promoter, Arabidopsis homologues to known mammalian and yeast transcription factors (TFs) downstream of MAPKs in MAPK pathways were identified through database searches. Binding sites in the lepr1b1 promoter for these homologous TFs were analyzed using Transfac, a TF database, and MatInspector program. The analysis indicated that the promoter contains potential binding sites for two TFs, Elf1 and AP1. A protoplast transient expression system was used in deletion and mutagenesis analysis. Mutation of the Elf1 binding site blocked activation of the LePR1b1 gene by tMEK2MUT. Mutation of the AP1 binding sites and of the GCC or W box, two regulatory elements found in some defense-related genes, had no effect on the expression of PR1b1. Our findings suggest that Elf1 is a downstream TF from MAPKK tMEK2 and is involved in mediating LePR1b1 gene expression in defense-related MAPK pathways.

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Keywords Elf1, Mitogen-activated protein kinase, Plant defense, Tomato, Transcription factor
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Journal Canadian Journal of Plant Pathology
Xing, T, Wang, X.-J. (X. J.), Malik, K. (K.), & Miki, B.L. (B. L.). (2003). Guided deletion and mutagenesis analysis identified a tMEK2-responsive region in tomato lepr1b1 promoter. Canadian Journal of Plant Pathology, 25(2), 209–214. doi:10.1080/07060660309507070