ULTRASTRUCTURE OF POTATO AND DATURA STRAMONIUM PLANT CELLS INFECTED WITH POTATO VIRUS X

This paper presents the results of a study of potato virus X (PVX) in the dynamics of the infectious process in cells of chlorotic and green areas of mosaic leaves of young Datura stramonium plants and in potatoes of the Kameraz I variety. Particles of the most virulent strain of PVX, Xs, were found first, on day 6 after inoculation, in the regions of virus penetration on young D. stramonium leaves in the cytoplasm and chloroplasts of cells of the epidermis, parenchyma, and conducting tissues. Particles of strains of medium virulence, the Kiev strain (Xk), and of least virulence, (Xr), were encountered later in large quantities, both diffusely distributed and densely packed in compact virus aggregates or inclusion bodies (X-bodies). These bodies included cellular components of the host. The volume of the vacuole was decreased by the many virus inclusions, and the virus aggregates that accumulated in the cytoplasm forced the tonoplast into protrusions which sometimes took the form of strands that penetrated the vacuoles. Virus particles in the plastids were detected as inclusions localized most frequently at the plastid ends. When such inclusions were surrounded by a membrane, they could be regarded as invaginations of the cytoplasm, but when no membrane was seen, organic association of the virus with the chloroplast could be assumed. Detailed examination of the fine structure of the X-bodies revealed ordered, linear, or variously curved groups of ribosomes arranged along fine, electron-opaque filaments like giant polysomes. At the end of the infection process, clusters or helices of fine filaments of unidentified material were found in the X-bodies. © 1969.