resistance to potyviruses ( Greenleaf, 1986 ; Villalon, 1981 ). The project to breed virus-resistant peppers at the Texas A&M Agricultural Experiment Station–Weslaco began in 1971. Several cultivars of virus-resistant peppers have been released over the last
Kevin M. Crosby, Justin Butcher, Kil Sun Yoo, and Daniel I. Leskovar
Mark J. Henning, Henry M. Munger, and Molly M. Jahn
`Hannah's Choice F1' is a new, high quality eastern type muskmelon (Cucumis melo L.) with multiple disease resistance. It was developed in the Department of Plant Breeding at the Cornell University Agricultural Experiment Station in Ithaca, N.Y. It is well adapted for northeastern U.S. conditions and shows potential for good adaptation in the northwest. With multiple disease resistance it is well suited for home gardeners, market gardeners, and commercial growers. `Hannah's Choice F1' has excellent resistance to powdery mildew races 1 and 2 (Podosphaera xanthi) and some tolerance to Fusarium root rot (Fusarium oxysporum f. sp. melonis) race 2. In addition, it has resistance to watermelon mosaic virus (WMV), papaya ringspot virus (PRSV), and zucchini yellow mosaic virus (ZYMV). This is the first commercial melon to have combined resistance to these three potyviruses. Also, it has shown some field tolerance to spider mites (Tetranychus urticae). Lastly, it has shown some field tolerance to downy mildew (Pseudoperonospora cubensis), angular leaf spot (Pseudomonas syringae pv. lachrymans), and gummy stem blight (Didymella bryoniae). In 2001, 2002, and 2003 it was grown in replicated trials in New York and in 2002 and 2003 in Oregon.
A.D. Bryan, J.R. Schultheis, Z. Pesic-VanEsbroeck, and G.C. Yencho
To determine the effects of Sweet potato feathery mottle virus (SPFMV), and possibly other newly described potyviruses, on sweetpotato yield and storage root appearance, virus-indexed `Beauregard' and `Hernandez' mericlones testing free of known viruses were compared with virus-infected mericlones in two separate experiments over two years. The experiments were arranged in a split-plot, randomized, complete-block design with the initial presence (VI+) or absence (VI-) of SPFMV as the whole plot factor and mericlone as the subplot factor. Plants were monitored weekly for symptoms of SPFMV and vine samples were taken for virus-indexing on Ipomoea setosa. Additional testing for selected sweetpotato viruses was done using a nitrocellulose membrane enzyme-linked immunosorbant assay. SPFMV was the only virus detected in the study, using available testing methodologies. Field monitoring indicated that §100% of the VI-plants were reinfected with SPFMV by 9 weeks after planting. The presence of virus before planting reduced yields of No. 1 roots by 26% and decreased overall appearance ratings for the three `Beauregard' mericlones. In addition, VI+ planting materials resulted in increased storage root length and reduced storage root width of both cultivars leading to increased storage root length/diameter ratios, further detracting from overall storage root appearance. The results of this study demonstrate that SPFMV contributes to cultivar decline in sweetpotato. However, the interaction of SPFMV with other newly described potyviruses, which may result in synergistic negative effects on sweetpotato yield and quality, needs further research.
Wilfredo Seda-Martínez, Linda Wessel-Beaver, Angela Linares-Ramírez, and Jose Carlos V. Rodrigues
PRSV and ZYMV are members of the genus Potyvirus and family Potyviridae . Most potyviruses have limited geographical distributions, but PRSV and ZYMV infect cucurbits all around the world ( Lecoq et al., 1998 ). Both viruses are easily
Kevin M. Crosby, John L. Jifon, Benigno Villalon, and Daniel I. Leskovar
-quality fruit. Multiple sources of single resistance genes against these potyviruses have been documented in various germplasm lines ( Cook, 1960 ; Greenleaf, 1956 ; Kyle and Palloix, 1997 ; Zitter and Cook, 1973 ). Origin ‘TAM Dulcito’ originated from
Kevin M. Crosby and Benigno Villalon
John F. Murphy and Fenny Dane
susceptible to each of the potyviruses. A 100% infection incidence occurred at 10 and 20 DPI for PRSV, WMV, and ZYMV ( Table 1 ). Each of the potyviruses induced systemic symptoms consisting of various forms of mosaic patterns on leaves, leaf deformation, and
Eileen Kabelka and Rebecca Grumet
Potyviruses cause severe loss in cucurbit crops. Inbred lines derived from the Chinese cucumber cultivar, Taichung Mau Gua (TMG), have been identified to be resistant to several potyviruses including zucchini yellow mosaic virus (ZYMV), zucchini yellow fleck virus, watermelon mosaic virus, and the watermelon strain of papaya ringspot virus. Recently, an additional virus that infects cucurbits, the Moroccan watermelon mosaic virus (MWMV), has been identified to be a distinct member of the potyvirus group. In this study, we sought to determine if TMG-1 is resistant to MWMV and, if so, examine whether a relationship exists between resistance to MWMV and resistance to ZYMV. Progeny analyses show that TMG-1 is resistant to MWMV and, like resistance to ZYMV, MWMV resistance is conferred by a single recessive gene. Sequential inoculation of progeny possessing resistance to ZYMV followed by MWMV (or MWMV followed by ZYMV) suggests that both resistances are conferred by the same gene, or two tightly linked genes. Additionally, all F3 families derived from F2 individuals selected for resistance to ZYMV, were resistant to MWMV. A second source of resistance to ZYMV, allelic to the TMG-1 source, has been incorporated into the Dutch hybrid Dina. Progeny analyses show Dina to posses a single recessive gene for MWMV resistance. As with TMG-1, no segregation of resistances was observed when ZYMV resistant progeny were inoculated with MWMV (or MWMV followed by ZYMV). Collectively, these results suggest that a single gene, or two tightly linked genes, control resistance to the potyviruses ZYMV and MWMV.
J.R. Fisher and S.T. Nameth
Ajuga reptans L. is an herbaceous ornamental mint grown in borders or as a groundcover, and is commonly propagated vegetatively and by seed. Three hundred and fifty-six A. reptans samples were obtained from growers in Washington, Michigan, Iowa, and Ohio, and screened for alfalfa mosaic virus (AMV), tobacco streak ilarvirus (TSV), cucumber mosaic cucumovirus (CMV), tomato aspermy cucumovirus (TAV), tomato spotted wilt tospovirus (TSWV), impatiens necrotic spot tospovirus (INSV), tobacco mosaic tobamovirus (TMV), potato virus × potexvirus (PVX), and 80 potyviruses, using direct antibody sandwich (DAS) and indirect enzyme-linked immunosorbent assay (ELISA). Viral-associated double-stranded ribonucleic acid (dsRNA) analysis was used to detect an apparent satellite (sat) RNA, and northern hybridization using a digoxigenin (DIG) labeled (S) CARNA-5 cDNA probe was used to confirm the identity of the apparent satRNA. No incidences of TAV, TMV, TSWV, INSV, PVX, or potyviruses were detected. CMV was detected in 11%, AMV in 22.2%, TSV in 3.7%, and mixed infections of CMV and AMV in 1.1% of the samples. SatRNA was detected in 36 A. reptans `Royalty', two `Rainbow', and two `Burgundy Glow' samples by dsRNA analysis, and confirmed by hybridization in 29 `Royalty' and one `Burgundy Glow' samples. Sixteen A. reptans `Royalty' seedlings grown from seed harvested from CMV-infected plants were tested by ELISA for CMV, AMV, and TSV. All were positive for CMV, and two were positive for a mixed infection of CMV and AMV. SatRNA was detected in all 16 seedlings by RT-PCR.
M-C Sanchez-Cuevas and S.G.P. Nameth
Double petunia plants expressing virus-like symptoms were collected in greenhouses and garden centers throughout Ohio in Spring 1997 and 1998 in an effort to determine the frequency and distribution of petunia viruses present in the state. Direct antibody-sandwich and indirect enzyme-linked immunosorbent assay (ELISA) were conducted with commercial antisera made against 13 viruses, a potyvirus kit capable of detecting 80 different potyviruses, and our antiserum raised against a tobamo-like virus inducing severe mosaic in double petunia. Viral-associated double-stranded ribonucleic acid (dsRNA) analysis and light microscopy for detection of inclusion bodies were also carried out. ELISA, dsRNA analysis, and light microscopy revealed the presence of tobacco mosaic tobamovirus, an unknown tobamo-like petunia virus, tomato ringspot nepovirus, tobacco streak ilarvirus, and tobacco ringspot nepovirus. Tomato aspermy cucumovirus, tomato spotted wilt tospovirus, impatiens necrotic spot tospovirus, alfalfa mosaic virus, cucumber mosaic cucumovirus, potato virus X potexvirus, and chrysanthemum B carlavirus were not detected. No potyviruses were identified. A number of plants with virus-like symptoms tested negative for all viruses.