ABSTRACT
Maize chlorotic dwarf virus (MCDV) particles differ from those of other known plant viruses of similar size and gross morphology in that they sediment faster and are denser. Isometric particles, assumed to be those of MCDV, have been observed embedded in electron-dense granular inclusions in the cytoplasm of phloem tissue cells and occasionally also in those of the mesophyll. MCDV-infected cells containing virus particles and granular inclusions also sometimes contained fibrillar material, accumulations of vesicles and particulate aggregates, and laminate inclusions of unidentified composition. It has been suggested that rice tungro virus (RTV) may be sufficiently similar to MCDV to be classified in the same group. It is interesting to note that in cells of rice plants infected with tungro disease, particles 28 to 30 nm in diameter have also been observed, embedded like the particles of MCDV, in electron-dense granular material.
