title: The double-resistance-breaking Tomato mosaic virus strain ToMV1-2 contains two independent single resistance-breaking domains.
abstract: Tomato mosaic virus (ToMV) causes a serious loss of yield and fruit quality in tomato crops. To control ToMV, three resistance genes, Tm-1, Tm-2, and Tm-2(2) from wild tomato species were introduced into commercial tomato cultivars. Soon after, however, single and, rarely, double-resistance-breaking virus strains for Tm-1 and Tm-2 emerged. Sequence analysis of a Tm-1/Tm-2 double-resistance-breaking virus, designated ToMV1-2, revealed 30 nucleotide substitutions compared with wild-type ToMV. Of these, six substitutions result in amino acid exchanges. Two exchanges are in the methyl transferase/helicase domain of the ToMV1-2 130/180-kDa proteins (D-1097 to V, R-1100 to Q), two exchanges are found in the 30-kDa movement protein (MP; E-52 to K, E-133 to K), and two exchanges are in the coat protein (I-22 to V, A-87 to S). Construction of chimeric full-length viral cDNA clones containing the base substitutions resulting in altered amino acids, either in the 130/180 kDa proteins or the MP, revealed that the amino acid exchanges in the 130/180-kDa proteins enable ToMV1-2 to break the Tm-1 resistance, while those in the MP enable ToMV1-2 to overcome the Tm-2 resistance. Furthermore, a novel Tm-1/Tm-2 double-resistance-breaking virus was generated by combining the Tm-1-breaking domain of ToMV1-2 and the MP of a new virus, ToMV2, containing the amino acid exchanges E-133 to K and N-135 to S. Together, the data suggest that double-resistance-breaking ToMV1-2 may have resulted from recombination between Tm-1 and Tm-2 single resistance-breaking virus strains.
authors.affiliation: Institut für Genetik, Universität Hohenheim, FG Allgemeine Virologie, Stuttgart, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Strasser
authors.forename: A J P
authors.initials: AJ
authors.lastname: Pfitzner
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D036022:Capsid Proteins / Q000235:genetics; D016679:Genome, Viral; D007113:Immunity, Innate; D018551:Solanum lycopersicum / Q000276:immunology / Q000821:virology*; D008780:Methyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009029:Mosaic Viruses / Q000235:genetics*; D010935:Plant Diseases / Q000821:virology*; D053830:Plant Viral Movement Proteins / Q000737:chemistry / Q000235:genetics*; D017434:Protein Structure, Tertiary / Q000235:genetics; D011995:Recombination, Genetic; D016415:Sequence Alignment; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D036022:Capsid Proteins; D053830:Plant Viral Movement Proteins; D014764:Viral Proteins; D008780:Methyltransferases