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Isolation and Characterization of a Virus from Saguaro Cactus. Gene M. Milbrath, Assistant Professor of Plant Pathology, Department of Plant Pathology, University of Illinois 61801; Merritt R. Nelson, Professor, Department of Plant Pathology, University of Arizona, Tucson 85721. Phytopathology 62:739-742. Accepted for publication 14 February 1972. DOI: 10.1094/Phyto-62-739.

An isometric virus was isolated from saguaro cactus (Carnegiea gigantea) in Arizona. This is the first virus found in this plant, and the first isometric virus to be isolated from the family Cactaceae. The virus is most easily isolated from the floral parts of the saguaro. The virion is ca. 35 nm in diam, contains less than 20% RNA, sediments as a single band in density-gradient centrifugation, and appears as a single component in the analytical ultracentrifuge. Antiserum to the saguaro virus antigen failed to show any serological relationship with 7 other isometric viruses tested. Chenopodium amaranticolor is a good local lesion host, whereas Chenopodium capitatum, a good systemic host, is useful as a source of virus for purification.