Key west nightshade, a new experimental host for plant viruses

Key West nightshade (Solanum bahamense) is a perennial solanaceous weed found in the extreme southern portion of Florida. It can be propagated by seed and cuttings and is absent from the noxious weed lists of all U.S. states. Its susceptibility to five viruses common to Florida was evaluated by mechanical inoculation of leaves with Tomato spotted wilt virus (TSWV), Tobacco mosaic virus (TMV), Pepper mild mottle virus (PMMoV), Cucumber mosaic virus (CMV), and a putative tobamovirus recently isolated from hibiscus in Florida (HV). TSWV induced chlorotic rings on inoculated leaves and mosaic and malformation of uninoculated leaves. CMV induced necrotic local lesions on inoculated leaves. No symptoms were observed following inoculation with TMV, PMMoV, or HV. TSWV, TMV, and PMMoV systemically infected S. bahamense as determined by the use of enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction, viral-associated double-stranded RNA analysis, and/or indicator hosts. Active growth of infected plants continued for 7 months following inoculation, making S. bahamense suitable for long-term maintenance of viruses in planta. We suggest that S. bahamense may be a useful host for virus culture collections and for studies involving large numbers of virus isolates where fresh, infected tissue is continuously required.