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Etiology

Properties and Cytopathology of Diodia Vein Chlorosis Virus—A New Whitefly-Transmitted Virus. R. C. Larsen, Department of Plant Pathology, University of Arkansas, Fayetteville 72701; K. S. Kim, and H. A. Scott. Department of Plant Pathology, University of Arkansas, Fayetteville 72701. Phytopathology 81:227-232. Accepted for publication 10 September 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-227.

A virus causing chlorosis and vein-clearing symptoms in Diodia virginiana from Arkansas was identified. The virus, designated as Diodia vein chlorosis virus (DVCV), was transmitted by the bandedwinged whitefly, Trialeurodes abutilonea, and by grafting but not by sap inoculation. T. abutilonea has not been reported to be a vector of plant viruses. Attempts to purify the virus resulted in low yields of fragmented flexuous rods approximately 12 nm in diameter. D. virginiana is the only known host plant for this virus. Ultrastructural studies of diseased leaves revealed the consistent presence of cytopathic effects characteristic of closterovirus infections. These include the occurrence of flexuous, rod-shaped viruslike particles, approximately 12 nm in diameter, in the cytoplasm of phloem parenchyma cells and sieve elements associated with membranous vesicles containing fibrils. In addition, greatly proliferated tubular membranes in the cytoplasm and unique double membrane-bound bodies within the vacuoles, which have not been reported to be associated with other closteroviruses, also were found. Double-stranded RNA isolated from DVCV-infected Diodia and subjected to polyacrylamide gel electrophoresis consisted of three bands with estimated M_r of 4.6, 4.3, and 1.9 × 10⁶, which were similar in nature to those exhibited by the closterovirus group. We conclude that the agent causing the symptoms in D. virginiana is probably a closterovirus.