Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/16/2006
Publication Date: 1/10/2007
Citation: Baker, C.A., Adkins, S.T. 2007. Tobacco ringspot virus found in the Cardboard Cycad, Zamia furfuracea, in Florida. Plant Disease. 91:112. Interpretive Summary: This is the first report of Tobacco ringspot virus (TRSV) infecting the cardboard cycad (Zamia furfuracea). A description of the host, symptoms and diagnostic methods used to confirm the identity of TRSV are presented. This report continues a cooperative virology research effort between ARS and FDACS-DPI, and provides a timely account of TRSV infection of ornamentals to growers, Extension personnel and state and Federal regulatory and research scientists.
Technical Abstract: In November 2005 a Zamia furfuracea plant, originally from Texas, was received at the Division of Plant Industry in Gainesville, Florida. The plant had numerous chlorotic spots on the leaves which eventually became necrotic. Leaves were ground in phosphate buffer (pH 7.2) with Carborundum and used to inoculate a host range that included Chenopodium amaranticolor, C. quinoa, Gomphrena globosa, Datura stramonium, and Nicotiana benthamiana. Systemic symptoms were seen in C. quinoa (necrotic lesions), G. globosa (stunting), D. stramonium (chlorotic ringspots), and N. benthamiana (wavy line patterns) 1-2 weeks after inoculation. C. amaranticolor showed only small necrotic local lesions. In further host range studies, systemic infections of Beta vulgaris, D. metaloides, Lactuca sativa, N. clevelandii, Pisum sativus, Zinnia elegans (symptomless) and Cucumis sativa were observed. However, no infection of Zea mays, Verbena hybrida, Glycine max, Phaseolus vulgaris, Catharanthus roseus, Arachis hypogaea, Trifolium spp, Vigna unguiculata, Vicia faba or Digitalis spp was detected. Inclusions observed in leaf strips of N. benthamiana and D. stramonium indicated a possible infection of this plant with a nepovirus. A 337 bp fragment was amplified from total RNA isolated from an inoculated D. stramonium using reverse transcription-polymerase chain reaction (RT-PCR) with nepovirus group primers. Sequence analysis indicated that the nucleotide (nt) and deduced amino acid (aa) sequences of the fragment were 89-91% and 91-95% identical, respectively, to sequences of the RNA-dependent RNA polymerase gene for Tobacco ringspot virus (TRSV) contained in GenBank. The original plant, symptomatic inoculated hosts, and the symptomless zinnia tested positive by DAS-ELISA using commercially-available antiserum for TRSV, further confirming the presence of TRSV. Although it has a more restricted host range than that reported for TRSV, the serology and gene sequence indicate that the virus infecting Z. furfuracea is an isolate of TRSV.