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

Abstract

<p>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 (<em>GmEREBP1</em>) 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 <em>GmEREBP1</em> activated the expression of the ethylene (ET)-responsive gene <em>PR2</em> and the ET- and jasmonic acid (JA)-responsive gene <em>PR3</em>, and the salicylic acid (SA)-responsive gene <em>PR1</em> but not the SA-responsive <em>PR5</em>. Similarly, transgenic <em>Arabidopsis</em> plants expressing <em>GmEREBP1</em> showed elevated mRNA abundance of the ET-regulated gene <em>PR3</em> and the ET- and JA-regulated defense-related gene <em>PDF1.2</em> but not the ET-regulated <em>GST2</em>, and the SA-regulated gene <em>PR1</em> but not the SA-regulated <em>PR2</em> and <em>PR5</em>. Transgenic soybean and <em>Arabidopsis</em> 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 <em>Arabidopsis</em> and mediates the expression of both ET- and JA- and SA-regulated defense-related genes in these plant species.</p>