title: Vitis vinifera VvNPR1.1 is the functional ortholog of AtNPR1 and its overexpression in grapevine triggers constitutive activation of PR genes and enhanced resistance to powdery mildew.
abstract: Studying grapevine (Vitis vinifera) innate defense mechanisms is a prerequisite to the development of new protection strategies, based on the stimulation of plant signaling pathways to trigger pathogen resistance. Two transcriptional coactivators (VvNPR1.1 and VvNPR1.2) with similarity to Arabidopsis thaliana NPR1 (Non-Expressor of PR genes 1), a well-characterized and key signaling element of the salicylic acid (SA) pathway, were recently isolated in Vitis vinifera. In this study, functional characterization of VvNPR1.1 and VvNPR1.2, including complementation of the Arabidopsis npr1 mutant, revealed that VvNPR1.1 is a functional ortholog of AtNPR1, whereas VvNPR1.2 likely has a different function. Ectopic overexpression of VvNPR1.1 in the Arabidopsis npr1-2 mutant restored plant growth at a high SA concentration, Pathogenesis Related 1 (PR1) gene expression after treatment with SA or bacterial inoculation, and resistance to virulent Pseudomonas syringae pv. maculicola bacteria. Moreover, stable overexpression of VvNPR1.1-GFP in V. vinifera resulted in constitutive nuclear localization of the fusion protein and enhanced PR gene expression in uninfected plants. Furthermore, grapevine plants overexpressing VvNPR1.1-GFP exhibited an enhanced resistance to powdery mildew infection. This work highlights the importance of the conserved SA/NPR1 signaling pathway for resistance to biotrophic pathogens in V. vinifera.
authors.affiliation: Université de Haute Alsace, Laboratoire Vigne, Biotechnologies et Environnement (EA3991), 33 rue de Herrlisheim, 68000, Colmar, France.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Le Henanff
authors.forename: Sibylle
authors.initials: S
authors.lastname: Farine
authors.forename: Flore
authors.initials: F
authors.lastname: Kieffer-Mazet
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Miclot
authors.forename: Thierry
authors.initials: T
authors.lastname: Heitz
authors.forename: Pere
authors.initials: P
authors.lastname: Mestre
authors.forename: Christophe
authors.initials: C
authors.lastname: Bertsch
authors.forename: Julie
authors.initials: J
authors.lastname: Chong
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology / Q000502:physiology; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001203:Ascomycota / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009154:Mutation; D010935:Plant Diseases / Q000382:microbiology*; D057865:Plant Immunity; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism / Q000382:microbiology / Q000502:physiology; D044224:Pseudomonas syringae / Q000502:physiology; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D027843:Vitis / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology / Q000502:physiology
chemical_list: D000890:Anti-Infective Agents; D029681:Arabidopsis Proteins; C105496:NPR1 protein, Arabidopsis; D010940:Plant Proteins; C053376:pathogenesis-related proteins, plant; D020156:Salicylic Acid