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Etiology

Ultrastructure of Datura stramonium Infected with an Euphorbia Virus Suggestive of a Whitefly-Transmitted Geminivirus. Kyung Soo Kim, Department of Plant Pathology, University of Arkansas, Fayetteville 72701; Robert W. Fulton, Department of Plant Pathology, University of Wisconsin-Madison, Madison 53706. Phytopathology 74:236-241. Accepted for publication 3 September 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-236.

Inoculation of Datura stramonium with an Euphorbia virus in raw leaf sap from wild Euphorbia heterophylla (which occurs widely in southern Florida), caused chlorotic lesions on inoculated primary leaves and mosaic or mottling on newly developed leaves. Thin-section electron microscopy of infected leaves revealed that the ultrastructural changes resembling those caused by whitefly-transmitted geminiviruses were greatly enhanced. These included the segregation of nucleolar components into discrete fibrillar and granular regions and the occurrence of fibrillar bodies in the nucleoplasm associated with isometric viruslike particles 15- 18 nm in diameter. In addition, certain cytopathic effects not common to other whitefly-transmitted geminiviruses were observed: the infection was not limited to phloem cells, and the occurrence of cytoplasmic inclusions surrounded by rough endoplasmic reticulum and Golgi bodies. In leaf dip preparations, viruslike particles appeared predominantly in pairs, which is typical of other geminiviruses. It is suggested that the Euphorbia virus belongs to the group of whitefly-transmitted geminiviruses.