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Detection of Viral Antigen by Immunogold Cytochemistry in Ovules, Pollen, and Anthers of Alfalfa Infected with Alfalfa Mosaic Virus. Z. Pesic, Graduate research assistant, Department of Plant Science, University of Alberta, Edmonton, Alberta T6G 2P5, Canada; C. Hiruki, and M. H. Chen. Professor, Research associate, respectively, Department of Plant Science, University of Alberta, Edmonton, Alberta T6G 2P5, Canada. Phytopathology 78:1027-1032. Accepted for publication 26 February 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-1027.

Alfalfa mosaic virus (AMV) was localized in alfalfa gametes by immunogold cytochemistry. AMV antigen was detected by immunogold labeling in the cytoplasm, and vacuoles of ovule integuments, microspores, mature pollen grains, and anther tapetum cells. Raftlike aggregates of virus particles and large crystalline bodies were observed in the cytoplasm of pollen grains and anther tapetum cells, while nonaggregated virions were detected in the vacuoles and the cytoplasm of ovule integument cells. This indicates that a mechanism exists for the transmission of AMV to seed through infected gametes. The immunogold technique was more sensitive than heavy metal straining in detecting the viral antigen in ultrathin sections of plant tissue. Staining with gold-labeled-goat anti-rabbit IgG was higher than with protein A-gold complex in purified virus preparations.