| Summary: | <p>Abstract</p> <p>Background</p> <p>Exposure of <it>Medicago truncatula </it>cell suspension cultures to pathogen or wound signals leads to accumulation of various classes of flavonoid and/or triterpene defense molecules, orchestrated via a complex signalling network in which transcription factors (TFs) are essential components.</p> <p>Results</p> <p>In this study, we analyzed TFs responding to yeast elicitor (YE) or methyl jasmonate (MJ). From 502 differentially expressed TFs, <it>WRKY </it>and <it>AP2/EREBP </it>gene families were over-represented among YE-induced genes whereas <it>Basic Helix-Loop-Helix </it>(<it>bHLH</it>) family members were more over-represented among the MJ-induced genes. Jasmonate ZIM-domain <it>(JAZ</it>) transcriptional regulators were highly induced by MJ treatment. To investigate potential involvement of <it>WRKY </it>TFs in signalling, we expressed four <it>Medicago WRKY </it>genes in tobacco. Levels of soluble and wall bound phenolic compounds and lignin were increased in all cases. <it>WRKY W109669 </it>also induced tobacco <it>endo-1,3-β-glucanase </it>(<it>NtPR2</it>) and enhanced the systemic defense response to tobacco mosaic virus in transgenic tobacco plants.</p> <p>Conclusion</p> <p>These results confirm that <it>Medicago WRKY </it>TFs have broad roles in orchestrating metabolic responses to biotic stress, and that they also represent potentially valuable reagents for engineering metabolic changes that impact pathogen resistance.</p>
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