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Cytology and Histology

Ultrastructural Host Cell Changes Associated With Tomato Yellow Mosaic. R. Lastra, Laboratorio de Virus de Plantas, Centro de Microbiología y Biología Celular, Instituto Venezolano de Investigaciones Científicas, Apartado 1827, Caracas, Venezuela; F. Gil, Laboratorio de Virus de Plantas, Centro de Microbiología y Biología Celular, Instituto Venezolano de Investigaciones Científicas, Apartado 1827, Caracas, Venezuela. Phytopathology 71:524-528. Accepted for publication 19 September 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-524.

Leaf phloem cells of tomato and Nicotiana glutinosa plants affected by tomato yellow mosaic (mosaico amarillo del tomate [MAT]) showed striking changes in nuclear morphology 6 days after inoculation either mechanically or by infectious whiteflies. The main changes were hypertrophy of the nucleus, which contained large masses of viruslike particles (18–20 nm in diameter), and often fibrillar rings also were observed. The viruslike particles were observed as large masses in the nuclei of infected phloem cells of both hosts. In N. glutinosa, however, they also occurred in the nuclei of mesophyll cells. Occasionally fibrillar rings were found in the nuclei of epidermal cells of N. glutinosa, but not in tomato. Comparable tissues from healthy plants were free of nucleopathy. The symptoms and signs of MAT resemble those reported for other whitefly-transmitted viruses such as bean golden mosaic virus and euphorbia mosaic virus.