title: Cloning and characterization of the durable tomato mosaic virus resistance gene Tm-2(2) from Lycopersicon esculentum.
abstract: In tomato, infections by tomato mosaic virus are controlled by durable Tm-2(2) resistance. In order to gain insight into the processes underlying disease resistance and its durability, we cloned and analysed the Tm-2(2) resistance gene and the susceptible allele, tm-2. The Tm-2(20 gene was isolated by transposon tagging using a screen in which plants with a destroyed Tm-2(2) gene survive. The Tm-2(2) locus consists of a single gene that encodes an 861 amino acid polypeptide, which belongs to the CC-NBS-LRR class of resistance proteins. The putative tm-2 allele was cloned from susceptible tomato lines via PCR with primers based on the Tm-2(2) sequence. Interestingly, the tm-2 gene has an open reading frame that is comparable to the Tm-2(2) allele. Between the tm-2 and the Tm-2(2) polypeptide 38 amino acid differences are present of which 26 are located in the second half of the LRR-domain. Susceptible tomato plants, which were transformed with the Tm-2(2) gene, displayed resistance against ToMV infection. In addition, virus specificity, displayed by the Tm-2(2) resistance was conserved in these transgenic lines. To explain the durability of this resistance, it is proposed that the Tm-2(2)-encoded resistance is aimed at the Achilles' heel of the virus.
authors.affiliation: Department Molecular Biology of Plants, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands. F.C.Lanfermeijer@biol.rug.nl
authors.forename: Frank C
authors.initials: FC
authors.lastname: Lanfermeijer
authors.forename: Jos
authors.initials: J
authors.lastname: Dijkhuis
authors.forename: Marcel J G
authors.initials: MJ
authors.lastname: Sturre
authors.forename: Peter
authors.initials: P
authors.lastname: de Haan
authors.forename: Jacques
authors.initials: J
authors.lastname: Hille
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004251:DNA Transposable Elements / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D007113:Immunity, Innate / Q000235:genetics; D018551:Solanum lycopersicum / Q000235:genetics* / Q000254:growth & development / Q000821:virology; D008969:Molecular Sequence Data; D009029:Mosaic Viruses / Q000254:growth & development; D009154:Mutation; D010935:Plant Diseases / Q000235:genetics* / Q000821:virology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D018744:DNA, Plant; D010940:Plant Proteins; D014764:Viral Proteins