ABSTRACT
This chapter provides a brief account of the development of studies on structure, composition, properties, cytopathology, and taxonomy of Bromoviruses. Bromoviruses are transmitted by mechanical inoculation, each to a limited number of host plants. Bromovirus particles can readily be dissociated by treating swollen particles with high concentrations of salts. The dissociation is reversible and particles of various polyhedral and tubular forms can be assembled in vitro. The Bromovirus genome is tripartite in that RNAs 1, 2, and 3 are all essential for infectivity. Bromo virus particles have been observed in the cytoplasm, vacuoles, and nuclei of infected cells. The most extensive studies on the cytopathology of Bromoviruses have been done with broad bean mottle virus. Autoradiographic experiments established that virus-dependent RNA synthesis occurred in the cytoplasm and was concentrated in small areas, often near golgi bodies. Infection by Bromoviruses causes proliferation of the endoplasmic reticulum and induces numerous, amorphous, electron-dense inclusions.
