ELECTRON-MICROSCOPIC STUDY OF POTATO-VIRUS X IN PARENCHYMAL-CELLS OF LIGHT AND DARK GREEN AREAS OF TOBACCO-LEAVES SYSTEMICALLY INFECTED WITH TOBACCO MOSAIC-VIRUS

Leaves of N. tabacum L. cv. Samsun systematically infected with tobacc o mosaic virus (TMV) were mechanically inoculated with potato virus X (PVX). PVX particles were observed with those of TMV in the parenchyma l cells of light green areas of the leaves. These PVX particles were m ainly present in dispersed form and small aggregates were found rarely . PVX-specific laminated inclusion bodies were often observed. Many ce lls had inclusions shaped as rings or as curved and straight rods, som e associated with fibrillar-granular inclusions. Few particles of TMV were observed in cells of the dark green areas of tobacco leaves syste mically infected with TMV. However, the number of cells of dark green areas containing TMV particles as well as the number of particles of T MV in them, increased when they were infected with PVX. PVX particles in such cells accumulated in cytoplasm of the cells and formed large a ggregations. Sometimes laminar inclusions were observed but these were smaller than in the cells of light green areas. The effect of PVX inf ection on the ultrastructure of cells was most pronounced in the cells of dark green areas.