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M.R. Stevens, P.D. Griffiths, J.W. Scott, D.K. Heiny, and D.D Rhoads

Sw-5 is a locus introgressed from Lycopersicon peruvianum to some L. esculentum lines conferring dominant resistance to TSWV. Restriction fragment length polymorphism (RFLP) analyses positions Sw-5 to the long arm of chromosome 9 in the sub-telomeric region between CT71 and CT220. RFLP analyses suggest the introgressed region begins distal to CT71, includes CT220, and may extend to the telomere. Randomly amplified polymorphic DNA (RAPD) analyses with >700 random 10-mer primers identified a single 2.2-kbp band with one primer (primer #72 GAGCACGGGA) that is tightly linked to Sw-5. However, we have also produced an equivalent 2.2-kbp band in analysis of other TSWV-susceptible tomato breeding lines. Thus, this band likely derives from L. esculentum DNA very near to Sw-5 and the introgressed region. Additional analyses have recently detected a potential co-dominant RAPD polymorphism linked to Sw-5.

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Mikel R. Stevens, John W. Scott, John J. Cho, Bradley D. Geary, and Frederic D. Memmott

Tomato spotted wilt virus (TSWV), a tospovirus, is a thrips-vectored disease infecting more than 1000 species of both monocots and dicots, including many species of agriculture importance. TSWV is the limiting factor for tomato (Lycopersicum esculentum Mill.) production in several areas of the world. For a number of years, the Sw-5 gene (derived from L. peruvianum Mill.) has provided acceptable control of this disease. Recently, Sw-5 derived resistance has been overcome by virulent pathogen isolate(s) in tomato production areas such as Spain and Italy. In earlier studies, we identified a potential new source of resistance to TSWV derived from L. chilense Dun. accession LA 1938. In a set of recent field studies, it was demonstrated that this putative new source of resistance was highly resistant to TSWV in Hawaii, Florida/Georgia, and South Africa. Furthermore, greenhouse screening trials have clearly demonstrated that the L. chilense source of TSWV resistance is resistant to isolates that overcome tomatoes homozygous for Sw-5. In these same greenhouse and field studies, there is uniform evidence that this resistance is dominant. Subsequent greenhouse studies suggest that this resistance is controlled by a single gene. Studies have been initiated to verify the inheritance of the gene(s) and to develop linked molecular markers. Furthermore, studies are under way in Australia to test this resistance on non-TSWV tospoviruses. If the data demonstrate that this is a single dominant gene we suggest this gene be designated Sw-7.

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Santiago García-Martínez, Adrián Grau, Aranzazu Alonso, Fernando Rubio, Manuel Valero, and Juan J. Ruiz

Spanish landraces has already resulted in the release of two breeding lines, UMH 1200 and UMH 1203, both homozygous for Tm-2 a , Ty-1, and Sw-5 genes ( García-Martínez et al., 2011 , 2012 ). These breeding lines allow farmers to obtain acceptable

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Santiago García-Martínez, Adrián Grau, Aranzazu Alonso, Fernando Rubio, Manuel Valero, and Juan J. Ruiz

’ line. Anastasia was used as the donor parent of the Tm-2 a , Sw-5, and Ty-1 genes ( Pérez de Castro et al., 2007 ), conferring resistance to ToMV, TSWV, and TYLCV, respectively. At the time the breeding program began, ‘Anastasia’ was a popular

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Matthew D. Robbins, Mohammed A.T. Masud, Dilip R. Panthee, Randolph G. Gardner, David M. Francis, and Mikel R. Stevens

; Gordillo et al., 2008 ). Both genes, Sw-5 for resistance to TSWV and Ph-3 for resistance to P. infestan s, were originally introgressed from wild relatives and confer high levels of pathogen resistance. The TSWV resistance gene Sw-5 was

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David G. Riley, Shimat V. Joseph, W. Terry Kelley, Steve Olson, and John Scott

relatively few promising genes that induce resistance have been identified (reviewed by Saidi and Warade, 2008 ). Among the thoroughly studied genes, Sw-5 from L. peruvianum ( Stevens et al., 1992 , 1994 , 1995 ), a new gene, Sw-7 from L. chilense

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M.J. Díez, S. Roselló, F. Nuez, J. Costa, M.S. Catalá, and A. Lacasa

Seedlings of three tomato (Lycopersicon esculentum Mill.) cultivars [`RDD', carrier of the Sw5 gene, which confers resistance to tomato spotted wilt virus (TSWV); `Pitihué', tolerant to the virus; and the susceptible cultivar Rutgers] were placed at the four- to five-leaf stage in cages containing a population of viruliferous thrips (Frankliniella occidentalis Perg.), and remained there for 0, 7, or 15 days. Plants were subsequently transplanted either into the open field or in tunnels protected with a mesh of 14 × 10 threads/cm. Systemic symptoms and number of dead plants were recorded and enzymelinked immunosorbent assays (ELISA) were performed. `Rutgers' exhibited severe systemic symptoms regardless of treatment and a high number of plants died. The level of infected plants remained low when protective measures were applied to seedlings of `Pitihué' and acceptable yields were obtained. In open air cultivation, where seedling infection was severe, <20% of `RDD' plants became infected and high yields were obtained; protected cultivation did not reduce yield. Although the percentage of infected plants was higher when cultivated under mesh, the yield of all three cultivars was greater than in the open field. The environment created under mesh stimulated growth, neutralizing the effect of the infection.

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Randy G. Gardner and Dilip R. Panthee

NC 58S, NC 123S, NC 127S, and NC 132S are fresh-market tomato ( Solanum lycopersicum L.) breeding lines that have the single dominant gene Sw-5 for resistance to tomato spotted wilt virus (TSWV) along with other important disease resistance genes

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Dilip R. Panthee and Randy G. Gardner

heterozygous for the I-3 gene for resistance to fusarium wilt race 3 [ Fusarium oxysporum f.sp. lycopersici (Sacc.) Snyd. and Hans.] and the Sw-5 gene for resistance to Tomato spotted wilt virus (TSWV). Fruits are high in soluble solids with an

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Dilip R. Panthee

f.sp. lycopersici (Sacc.) Snyd. and Hans.] races 1, 2, and 3 ( I, I-2 , and I-3 genes); root-knot nematodes ( Meloidogyne spp., Mi gene); Tomato mosaic virus ( Tm-2 gene); and Tomato spotted wilt virus ( Sw-5 gene). Origin The