title: Simultaneous induction of jasmonic acid and disease-responsive genes signifies tolerance of American elm to Dutch elm disease.
abstract: Dutch elm disease (DED), caused by three fungal species in the genus Ophiostoma, is the most devastating disease of both native European and North American elm trees. Although many tolerant cultivars have been identified and released, the tolerance mechanisms are not well understood and true resistance has not yet been achieved. Here we show that the expression of disease-responsive genes in reactions leading to tolerance or susceptibility is significantly differentiated within the first 144 hours post-inoculation (hpi). Analysis of the levels of endogenous plant defense molecules such as jasmonic acid (JA) and salicylic acid (SA) in tolerant and susceptible American elm saplings suggested SA and methyl-jasmonate as potential defense response elicitors, which was further confirmed by field observations. However, the tolerant phenotype can be best characterized by a concurrent induction of JA and disease-responsive genes at 96 hpi. Molecular investigations indicated that the expression of fungal genes (i.e. cerato ulmin) was also modulated by endogenous SA and JA and this response was unique among aggressive and non-aggressive fungal strains. The present study not only provides better understanding of tolerance mechanisms to DED, but also represents a first, verified template for examining simultaneous transcriptomic changes during American elm-fungus interactions.
authors.affiliation: Gosling Research Institute for Plant Preservation, Department of Plant Agriculture, University of Guelph, Guelph, ON, Canada.|Department of Horticulture, Faculty of Agriculture, Damanhour University, Al-Gomhuria St., PO Box 22516, Damanhour, Al-Behira, Egypt.
authors.forename: S M
authors.initials: SM
authors.lastname: Sherif
authors.affiliation: Gosling Research Institute for Plant Preservation, Department of Plant Agriculture, University of Guelph, Guelph, ON, Canada.
authors.forename: M R
authors.initials: MR
authors.lastname: Shukla
authors.affiliation: Chemistry Department, University of British Columbia, Kelowna, BC, Canada.
authors.forename: S J
authors.initials: SJ
authors.lastname: Murch
authors.affiliation: Centre d'étude de la forêt (CEF) and Institut de biologie intégrative et des systèmes (IBIS), Université Laval, Québec City, QC, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Bernier
authors.affiliation: Gosling Research Institute for Plant Preservation, Department of Plant Agriculture, University of Guelph, Guelph, ON, Canada.
authors.forename: P K
authors.initials: PK
authors.lastname: Saxena
mesh_terms: D000085:Acetates / Q000276:immunology / Q000378:metabolism; D003517:Cyclopentanes / Q000276:immunology / Q000378:metabolism*; D004198:Disease Susceptibility; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D007108:Immune Tolerance; D058977:Molecular Sequence Annotation; D055156:Ophiostoma / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D054883:Oxylipins / Q000276:immunology / Q000378:metabolism*; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics* / Q000276:immunology; D020156:Salicylic Acid / Q000276:immunology / Q000378:metabolism; D013997:Time Factors; D034403:Ulmus / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D014774:Virulence
chemical_list: D000085:Acetates; D003517:Cyclopentanes; D005656:Fungal Proteins; D054883:Oxylipins; D010940:Plant Proteins; C011006:jasmonic acid; C072239:methyl jasmonate; D020156:Salicylic Acid