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Ecology and Epidemiology

Location of Prune Dwarf and Prunus Necrotic Ringspot Viruses Associated with Sweet Cherry Pollen and Seed. R. D. Kelley, Graduate research assistant, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; H. R. Cameron, professor, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331. Phytopathology 76:317-322. Accepted for publication 9 October 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-317.

The location of prune dwarf virus (PDV) and Prunus necrotic ringspot virus (PNRSV) in pollen and seed from infected and healthy sweet cherry trees pollinated with pollen from infected trees was investigated by means of electron microscopy and enzyme-linked immunosorbent assay (ELISA). Transmission electron microscopy revealed viruslike particles in the cytoplasm of pollen grains from PDV-infected cherry trees. No particles were observed in pollen from PNRSV-infected or noninfected trees. Both viruses were detected by ELISA in all parts of fruit from infected trees pollinated with pollen from healthy trees. Both viruses were detected in the cotyledons, hypocotyl-radicle tissues, and testa-nucellus-endosperm tissues but not in the mesocarp of fruit from caged healthy trees bee-pollinated with pollen from infected trees or in infected fruit of healthy orchard trees hand-pollinated with pollen from infected trees. Antigen levels in the buffer from successive washings of pollen from infected trees decreased steadily. Antigen levels were high in pollen samples that had been washed, then ground in buffer, even those treated before grinding with antiserum to bind all available antigenic sites. Attempts to transmit PNRSV to cherry fruit by pollination with pollen from PNRSV-infected almond failed.