title: The movement protein (NSm) of Tomato spotted wilt virus is the avirulence determinant in the tomato Sw-5 gene-based resistance.
abstract: The avirulence determinant triggering the resistance conferred by the tomato gene Sw-5 against Tomato spotted wilt virus (TSWV) is still unresolved. Sequence comparison showed two substitutions (C118Y and T120N) in the movement protein NSm present only in TSWV resistance-breaking (RB) isolates. In this work, transient expression of NSm of three TSWV isolates [RB1 (T120N), RB2 (C118Y) and non-resistance-breaking (NRB)] in Nicotiana benthamiana expressing Sw-5 showed a hypersensitive response (HR) only with NRB. Exchange of the movement protein of Alfalfa mosaic virus (AMV) with NSm supported cell-to-cell and systemic transport of the chimeric AMV RNAs into N. tabacum with or without Sw-5, except for the constructs with NBR when Sw-5 was expressed, although RB2 showed reduced cell-to-cell transport. Mutational analysis revealed that N120 was sufficient to avoid the HR, but the substitution V130I was required for systemic transport. Finally, co-inoculation of RB and NRB AMV chimeric constructs showed different prevalence of RB or NBR depending on the presence or absence of Sw-5. These results indicate that NSm is the avirulence determinant for Sw-5 resistance, and mutations C118Y and T120N are responsible for resistance breakdown and have a fitness penalty in the context of the heterologous AMV system.
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, 46022, Valencia, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Peiró
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Cañizares
authors.forename: Luis
authors.initials: L
authors.lastname: Rubio
authors.forename: Carmelo
authors.initials: C
authors.lastname: López
authors.forename: Enrique
authors.initials: E
authors.lastname: Moriones
authors.forename: José
authors.initials: J
authors.lastname: Aramburu
authors.forename: Jesús
authors.initials: J
authors.lastname: Sánchez-Navarro
mesh_terms: D017794:Alfalfa mosaic virus / Q000502:physiology; D001681:Biological Assay; D004252:DNA Mutational Analysis; D060467:Disease Resistance; D017343:Genes, Plant; D018551:Solanum lycopersicum / Q000235:genetics* / Q000821:virology*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics / Q000821:virology*; D053830:Plant Viral Movement Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified; D014026:Nicotiana / Q000235:genetics; D017865:Tospovirus / Q000378:metabolism* / Q000472:pathogenicity*; D014774:Virulence
chemical_list: D053830:Plant Viral Movement Proteins
keywords: Avr; Tospovirus; competition assays; movement protein NSm; transient expression