First Report of Carnation mottle virus in Calla lily (Zantedeschia spp.).

Calla lilies are ornamental plants of major economic importance in Taiwan. They are grown in the central and northern areas of the island, and ≈3 million stems are shipped annually. Calla lilies are susceptible to several viruses (1). Infections by Cucumber mosaic virus, Dasheen mosaic virus, Turnip mosaic virus, and Watermelon silver mottle virus were reported in Taiwan. Recently, virus-like symptoms including yellow mottling, light yellow spot, yellow ringspot, and mosaic were observed on leaves of field-grown calla lilies from Changhua County, located in central Taiwan. In March 2001, a virus culture was isolated from diseased calla lilies and established in Chenopodium quinoa Willd. and Nicotiana benthamiana Domin. When inoculated with the virus, healthy calla lilies developed chlorotic spots that enlarged and fused to form large, yellow patches on inoculated leaves. Symptoms were similar to those on the naturally infected plants observed in the fields. The virus induced chlorotic local lesions on C. quinoa, C. ficifolium Sm., C. amaranticolor Coste & Reyn, Cucurbita moschata Duchesne ex Poir, Lisianthus russellianum (Don.) Griseb, Phaseolus angularis Wight, Vigna angularis Willd., and V. radiata (L.) Wilczek. In addition to the localized chlorotic spots on inoculated leaves, systemic invasion of the virus was also observed 8 to 10 days postinoculation in Dianthus caryophyllus L., D. chinensis L., and Glycine max Merr. In N. benthamiana, the only symptom observed was systemic wilting. Examination of 2% of uranyl-acetate-stained samples using electron microscopy revealed the presence of spherical particles ≈34 to 35 nm in diameter in crude extracts of leaves of diseased calla lilies, or infected C. quinoa. Similar particles were also observed in the cytoplasm but not in the nuclei in ultrathin sections of virus-infected leaf tissues of C. quinoa and N. benthamiana. Differential centrifugation followed by sucrose density gradient centrifugation of tissue extracts of infected C. quinoa yielded virions with similar size. Sodium dodesyl sulfate polyacrylamide gel electrophoresis of the purified virus showed a single structural polypeptide ith a M_r of 41.6 kDa. The viral antigen reacted positively with its homologous antiserum and an antiserum against Carnation mottle virus (CarMV; Agdia, Inc., Elkhart, IN) in double antibody sandwich enzyme-linked immunosorbent assay. Using primers 5'-CTCCATGGTCATGGAA(A/G)ATAAA GGAGAA and 3'-CAACAAATATCCTACACTGTCCTAGGTG specific to the coat protein (CP) gene of CarMV, an expected viral CP gene product of 1.05 kb was amplified by reverse transcription-polymerase chain reaction from total RNA isolated from infected N. benthamiana. Comparisons of the 1,047-nucleotide CP gene with those of 15 CarMV isolates available in GenBank showed 94.6 to 98.2% nucleotide identity and 94.8 to 96.8% amino acid identity. Results from current studies indicate that the virus infecting calla lilies is an isolate of CarMV. To our knowledge, this is the first report of CarMV infection in calla lilies. The occurrence of CarMV in calla lilies has direct implication for the economically important nursery and floral industry in Taiwan. Reference: (1) F. W. Zettler and R. D. Hartman. Dieffenbachia, Caladium, and Zantedeschia. Pages 464-470 in: Virus and Virus-Like Diseases of Bulb and Flower Crops. G. Loebenstein, R. H. Lawson, and A. A. Brunt, eds. John Wiley and Sons, West Sussex, U.K., 1995.