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Cytological Alterations in Cells Infected with Corn Leaf Aphid-Specific Isolates of Barley Yellow Dwarf Virus. C. C. Gill, Research scientist, Agriculture Canada, Research Station, 195 Dafoe Road, Winnipeg, Manitoba, R3T 2M9, Canada; J. Chong, electron microscope technician, Agriculture Canada, Research Station, 195 Dafoe Road, Winnipeg, Manitoba, R3T 2M9, Canada. Phytopathology 69:363-368. Accepted for publication 5 October 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-363.

Electron microscopic examination of tissue from oat (Avena sativa) leaves infected with Rhopalosiphum maidis (corn leaf aphid)-specific isolates of barley yellow dwarf virus (BYDV) revealed that alterations in infected phloem cells were basically similar to those described earlier for R. padi (cherry oat aphid)-specific isolates but differed from those in cells infected with Macrosiphum avenae (English grain aphid)-specific and aphid-nonspecific isolates of BYDV. Alterations that were the same for R. maidis-specific and R. padi-specific isolates were the presence in the cytoplasm of vesicular membranous inclusion bodies that contained fibrillar material and that were enclosed by a second membrane; alterations in the nucleus involved the association of viruslike particles with distorted nucleoli. These particles also became distributed through the nucleoplasm and the cytoplasm. The nuclear heterochromatin showed progressive dissolution. Masses of proliferated tubular membranes in the cytoplasm were much more extensively developed than those with R. padi-specific isolates. Also, there were no densely staining filaments associated with virus particles in mature sieve elements and no pathological alterations in mitochondria; cell wall deposits were extensive in most infected cells. Massive clumps of virus particles in the cytoplasm late in the infection also were unique.