Electron microscopy of inclusions associated with wheat streak mosaic virus

Identification of Wheat streak mosaic virus and Its Vector Aceria tosichella in Mexico

The objective of this study was to identify a pathogen observed in wheat in the Texcoco area (Mexico). The symptoms induced by this pathogen are consistent with those caused by a virus. Identification was based on host range, symptoms, mode of transmission, and on serological and morphological characterization. The pathogen was mechanically transmitted to Triticum aestivum, T. durum, Secale cereale, × Triticosecale, Avena sativa, and Hordeum vulgare. The virus particles were flexuous rods, 700 nm long that produced cylindrical inclusions seen as pinwheel inclusions under the electron microscope. The pathogen reacted with Wheat streak mosaic virus (WSMV) antibodies in enzyme-linked immunosorbent assay. An eriophyoid mite associated with this virus was identified as Aceria tosichella and found to transmit the virus efficiently. Based on its characteristics, the pathogen was identified as WSMV. During this study, the virus appeared sporadically in test plots without causing significant yield losses.

Particle arrangements in proplastids of Triticum vulgare L. seedlings

Particles having ribosome-like characteristics are described in proplastids of dark-grown wheat seedlings as the membranes of the prolamellar body become transformed, under the influence of light, into grana and fret membranes. Three arrangements of particles were noted: (1) a random distribution of discrete particles; (2) particles occurring in helices or parallel rows; and (3) particles arranged in rough squares with six to eight particles per side. It is possible that the third type of particle is a cross-section of long parallel rods. A particle ranges in size from 170 to 220 A, those of group three being somewhat smaller. The particulates vary from diamond shaped with smooth surfaces to circular with irregular surfaces. These particles have the characteristics of ribosomes as visualized by the electron microscope: they are preserved by glutaraldehyde and osmium tetroxide, they stain intensely with uranyl acetate, and are digested by RNase. Their properties do not coincide with those of viruses, smog-induced particles, stromacenter particles, or phytoferritin. They are frequently adjacent to membranes but never attached to membranes. The involvement of ribosomes in membrane development is discussed.

Cylindrical Inclusions in the Cytoplasm of Leaf Cells Infected with Tobacco Etch Virus

Combined tracings from electron micrographs of serial sections of leaf tissue infected with tobacco etch virus show that one type of cytoplasmic inclusion, when sectioned in different planes, can produce configurations which have been interpreted as being two distinct types of inclusion bodies.