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GmEREBP1 Is a Transcription Factor Activating Defense Genes in Soybean and Arabidopsis

February 2007 , Volume 20 , Number  2
Pages  107 - 119

Mitra Mazarei,1 Axel A. Elling,1,2 Tom R. Maier,1 David P. Puthoff,1 and Thomas J. Baum1,2

1Department of Plant Pathology and 2Interdepartmental Genetics Program, Iowa State University, Ames 50011, U.S.A.

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Accepted 28 August 2006.

Ethylene-responsive element-binding proteins (EREBPs) are plant-specific transcription factors, many of which have been linked to plant defense responses. Conserved EREBP domains bind to the GCC box, a promoter element found in pathogenesis-related (PR) genes. We previously identified an EREBP gene from soybean (GmEREBP1) whose transcript abundance decreased in soybean cyst-nematode-infected roots of a susceptible cultivar, whereas it increased in abundance in infected roots of a resistant cultivar. Here, we report further characterization of this gene. Transient expression analyses showed that GmEREBP1 is localized to the plant nucleus and functions as a transcriptional activator in soybean leaves. Transgenic soybean plants expressing GmEREBP1 activated the expression of the ethylene (ET)-responsive gene PR2 and the ET- and jasmonic acid (JA)-responsive gene PR3, and the salicylic acid (SA)-responsive gene PR1 but not the SA-responsive PR5. Similarly, transgenic Arabidopsis plants expressing GmEREBP1 showed elevated mRNA abundance of the ET-regulated gene PR3 and the ET- and JA-regulated defense-related gene PDF1.2 but not the ET-regulated GST2, and the SA-regulated gene PR1 but not the SA-regulated PR2 and PR5. Transgenic soybean and Arabidopsis plants inoculated with cyst nematodes did not display a significantly altered susceptibility to nematode infection. These results collectively show that GmEREBP1 functions as a transacting inducer of defense gene expression in both soybean and Arabidopsis and mediates the expression of both ET- and JA- and SA-regulated defense-related genes in these plant species.

Additional keywords:cis elements, ethylene-insensitive soybean mutant etr1-1, GFP, GUS, protoplasts, quantitative real-time reverse-transcription PCR.

© 2007 The American Phytopathological Society