title: T3SS-dependent differential modulations of the jasmonic acid pathway in susceptible and resistant genotypes of Malus spp. challenged with Erwinia amylovora.
abstract: Fire blight is a bacterial disease of Maloideae caused by Erwinia amylovora (Ea). This necrogenic enterobacterium uses a type III secretion system (T3SS) to inject type III effectors into the plant cells to cause disease on its susceptible hosts, including economically important crops like apple and pear. The expressions of marker genes of the salicylic acid (SA) and jasmonic acid (JA) defense regulation pathways were monitored by RT-qPCR in leaves of two apple genotypes, one susceptible and one resistant, challenged with a wild type strain, a T3SS-deficient strain or water. The transcriptional data taken together with hormone level measurements indicated that the SA pathway was similarly induced in both apple genotypes during infection by Ea. On the contrary, the data clearly showed a strong T3SS-dependent down-regulation of the JA pathway in leaves of the susceptible genotype but not in those of the resistant one. Accordingly, methyl-jasmonate treated susceptible plants displayed an increased resistance to Ea. Bacterial mutant analysis indicated that JA manipulation by Ea mainly relies on the type III effector DspA/E. Taken together, our data suggest that the T3SS-dependent down-regulation of the JA pathway is a critical step in the infection process of Malus spp. by Ea.
authors.affiliation: Institut de Recherche en Horticulture et Semences, UMR INRA/Agrocampus Ouest/Université d'Angers, F-49071 Angers, France. Thomas.Duge-de-Bernonville@toulouse.inra.fr
authors.forename: Thomas
authors.initials: T
authors.lastname: Dugé De Bernonville
authors.forename: Matthieu
authors.initials: M
authors.lastname: Gaucher
authors.forename: Victor
authors.initials: V
authors.lastname: Flors
authors.forename: Sylvain
authors.initials: S
authors.lastname: Gaillard
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Paulin
authors.forename: James F
authors.initials: JF
authors.lastname: Dat
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Brisset
mesh_terms: D000085:Acetates / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D015536:Down-Regulation; D044084:Erwinia amylovora / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D054884:Host-Pathogen Interactions; D027845:Malus / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000502:physiology*; D009154:Mutation; D054883:Oxylipins / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D010935:Plant Diseases / Q000382:microbiology*; D057865:Plant Immunity; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D020156:Salicylic Acid / Q000032:analysis / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013997:Time Factors
chemical_list: D000085:Acetates; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D003517:Cyclopentanes; C110611:DspA protein, Erwinia amylovora; D054883:Oxylipins; D010940:Plant Proteins; D018749:RNA, Plant; C075462:harpin protein, Erwinia amylovora; C011006:jasmonic acid; C072239:methyl jasmonate; D020156:Salicylic Acid