Genetic mapping of the Tsw locus for resistance to the Tospovirus Tomato spotted wilt virus in Capsicum spp. and its relationship to the Sw-5 gene for resistance to the same pathogen in tomato

The Tsw gene conferring dominant resistance to the Tospovirus Tomato spotte d wilt virus (TSWV) in Capsicum spp, has been tagged with a random amplifie d polymorphic DNA marker and mapped to the distal portion of chromosome 10, No mapped homologues of Sw-5, a phenotypically similar dominant TSWV resis tance gene in tomato, map to this region in C. annuum, although a number of Sw-5 homologues are found at corresponding positions in pepper and tomato. The relationship between Tsw and Sw-5 was also examined through genetic st udies of TSWV, The capacity of TSWV-A to overcome the Tsw gene in pepper an d the Sw-5 gene In tomato maps to different TSWV genome segments. Therefore , despite phenotypic and genetic similarities of resistance in tomato and p epper, we infer that distinct viral gene products control the outcome of in fection in plants carrying Sw-5 and Tsw, and that these loci do not appear to share a recent common evolutionary ancestor.