Isolation and partial characterization of an unknown virus from Cornus florida L.

A virus was isolated from a flowering dogwood, Cornus florida. The dogwood had no specific virus disease symptoms, though it had a generally unthrifty appearance. The virus was mechanically transmissible to plants in the Family Chenopodiaceae. The virus caused irregularly shaped, reddish-purple lesions on inoculated leaves of Beta vulgaris, and chlorotic and necrotic lesions on inoculated leaves of Chenopodium amaranticolor, C. murale, and C. quinoa. Systemic symptoms were chlorotic mottling on C. amaranticolor, chlorotic blotches and twisted growth on C. murale, and chlorotic and necrotic lesions on C. quinoa. Beta vulgaris was not systemically infected. Virus infected Spinacia oleracea were symptomless. The dilution end point was 10^-3 to 10^-5. The longevity in vitro at 25 C was 31 to 35 days. Dried tissue stored at -7 C was still infective after one year. The thermal inactivation point was 50 to 60 C. Virus was purified from tissue ground in phosphate buffer, with diethyldithiocarbamate (DIECA) and thioglycollate added. The preparation was emulsified with chloroform, given three cycles of differential centrifugation and centrifuged through a sucrose density gradient. Partially purified virus was tested using the Ouchterlony agar gel double diffusion test for reaction to antisera of seven viruses reported to infect dogwood. The virus isolate reacted to tomato ringspot virus antiserum with the formation of a single precipitin band. Purified virus preparations examined by transmission electron microscopy had icosahedral particles, estimated to be 30 nm in diameter.