VIEW ARTICLE

Cytology and Histology

Alteration of Major Cellular Organelles in Wheat Leaf Tissue Infected with Wheat Streak Mosaic Rymovirus (Potyviridae). Jian- Guo Gao,Department of Botany, University of Guelph, Guelph, Ontario, Canada N1G 2W1; Annette Nassuth, Department of Botany, University of Guelph, Guelph, Ontario, Canada N1G 2W1. Phytopathology 83:206-213. Accepted for publication 10 November 1992. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/Phyto-83-206.

The alteration of cell organelles in wheat leaf cells systemically infected with wheat streak mosaic virus was quantitatively investigated at both light- and electron-microscopy levels. Nuclei significantly increased in size at an early stage of infection and contained dispersed heterochromatin. The nuclear envelope was frequently invaginated and had formed membrane-bound vesicles containing membranes, ribosomes, cylindrical inclusions, virus particles, and, occasionally, fibrils and mitochondria. Chloroplasts in infected tissue were smaller, frequently had extrusions, and contained far less starch than chloroplasts in healthy tissue. Many chloroplasts formed double membrane-bound invaginations in the envelope membrane. Virus particles and mitochondria were found within the invaginations. The viral infection also caused the chloroplast envelope’s inner membrane to proliferate and fold repeatedly, dividing the stroma into numerous single membrane-bound fragments. Double membrane-bound elongated tubular structures accumulated in large quantities within the cytoplasm of infected cells. Labeling with rabbit antiribulose bisphosphate oxygenase-carboxylase serum proved that these structures were derived from chloroplasts, possibly via extrusions. The mitochondria in infected cells were lobed and contained degenerated cristae membranes. The peroxisomes became electron lucent and contained platelike inclusions. A large amount of electron-opaque material accumulated in the vacuole.