Vellaisamy, Ramamoorthy , Zhao, Xinhua , Snyder, Anita , Xu, Jin-Rong , Shah, Dilip .
Two mitogen-activated protein kinase signaling cascades mediate basal resistance to antifungal plant defensins in Fusarium graminearum.
Antifungal defensins, MsDef1 and MtDef4, from Medicago spp., inhibit the growth of Fusarium graminearum which causes head blight disease in cereals. In order to determine the signaling cascades that are modulated by these defensins, we have isolated several insertional mutants of F. graminearum that exhibit hypersensitivity to MsDef1, but not to MtDef4. The molecular characterization of two of these mutants, designated enhanced sensitivity to defensin (esd), has revealed that the Mgv1 and Gpmk1 MAP kinase signaling cascades play a major role in regulating sensitivity of F. graminearum to MsDef1, but not to MtDef4. The Hog1 MAP kinase signaling cascade, which is responsible for adaptation of this fungus to hyperosmotic stress, does not participate in the fungal response to these defensins. Significantly, the esd mutants also exhibit hypersensitivity to other tested defensins and are highly compromised in their pathogenesis on wheat heads and tomato fruits. The studies reported here for the first time implicate two MAP kinase signaling cascades in a plant defensin-mediated alteration of fungal growth. Based on our findings, we propose that specific MAP kinase signaling cascades are essential for protection of a fungal pathogen from the antimicrobial proteins of its host plant.
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1 - Donald Danforth Plant Science Center, 975 North Warson Rd, St louis, MO, 63132, USA
2 - Purdue University, Department of Botany and Plant Pathology, West Lafayette, IN, 47907, USA
wheat head blight
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM