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Thesis (M.S.)—University of Nebraska—Lincoln, 1967. Department of Botany (Plant Pathology).


Copyright 1967, the author. Used by permission.


Soil-borne wheat mosaic virus particles in thin sections of infected leaves and primary and secondary roots of Michigan Amber wheat were examined in the electron microscope and compared to particles seen in sections of pellets of partially purified virus.In both the pellet and the infected host tissue the rod-shaped virus particles possessed a hollow nucleic acid core within a protein shell.Within the host, the virus particles were frequently observed in small aggregates in the central vacuole of older cells.Cross sections through these aggregates showed a hexagonal arrangement of particles such that each particle was surrounded by six symmetrically placed neighbors.Small connections between the nucleic acid cores of adjacent viruses were sometimes evident. The same characteristic pattern was observed with various fixing and straining methods.Unidentified bacteria were also observed in both primary and secondary roots.

Similar methods applied to the resting spores of the presumed vector of the virus, Polymyxa graminis Led., revealed probable storage materials, cytoplasmic and nuclear constituents.Some empty spores contained unidentified bacteria.No virus aggregates or inclusions similar to those seen in plant cells were detected in sections of 240 P. graminis resting spores.

Advisor: M. K. Brakke