title: Tobacco etch virus infectivity in Capsicum spp. is determined by a maximum of three amino acids in the viral virulence determinant VPg.
abstract: Potyvirus resistance in Capsicum spp. has been attributed to amino acid substitutions at the pvr1 locus that cause conformational shifts in eukaryotic translation initiation factor eIF4E. The viral genome-linked protein (VPg) sequence was isolated and compared from three Tobacco etch virus (TEV) strains, highly aphid-transmissible (HAT), Mex21, and N, which differentially infect Capsicum genotypes encoding Pvr1(+), pvr1, and pvr1(2). Viral chimeras were synthesized using the TEV-HAT genome, replacing HAT VPg with Mex21 or N VPg. TEV HAT did not infect pepper plants homozygous for either the pvr1 or pvr1(2) allele. However, the novel chimeric TEV strains, TEVHAT(Mex21-VPg) and TEV-HAT(N-VPg), infected pvr1 and pvr1(2) pepper plants, respectively, demonstrating that VPg is the virulence determinant in this pathosystem. Three dimensional structural models predicted interaction between VPg and the susceptible eIF4E genotype in every case, while resistant genotypes were never predicted to interact. To determine whether there is a correlation between physical interaction of VPg with eIF4E and infectivity, the effects of amino acid variation within VPg were assessed. Interaction between pvr1(2) eIF4E and N VPg was detected in planta, implying that the six amino acid differences in N VPg relative to HAT VPg are responsible for restoring the physical interaction and infectivity.
authors.affiliation: Department of Plant Breeding and Genetics, Cornell University, Ithaca, NY, USA.
authors.forename: Kari
authors.initials: K
authors.lastname: Perez
authors.forename: Inhwa
authors.initials: I
authors.lastname: Yeam
authors.forename: Byoung-Cheorl
authors.initials: BC
authors.lastname: Kang
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Ripoll
authors.forename: Jinhee
authors.initials: J
authors.lastname: Kim
authors.forename: John F
authors.initials: JF
authors.lastname: Murphy
authors.forename: Molly M
authors.initials: MM
authors.lastname: Jahn
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D002212:Capsicum / Q000276:immunology / Q000821:virology*; D002678:Chimera; D060467:Disease Resistance / Q000235:genetics; D039561:Eukaryotic Initiation Factor-4E / Q000235:genetics* / Q000502:physiology; D016679:Genome, Viral / Q000235:genetics; D054884:Host-Pathogen Interactions; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000821:virology; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology; D017800:Potyvirus / Q000235:genetics* / Q000472:pathogenicity; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D016415:Sequence Alignment; D014026:Nicotiana / Q000235:genetics; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D037521:Virulence Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D039561:Eukaryotic Initiation Factor-4E; D010940:Plant Proteins; D014764:Viral Proteins; D037521:Virulence Factors