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Cytology and Histology

Nuclear Changes Associated with Euphorbia Mosaic Virus Transmitted by the Whitefly. K. S. Kim, Associate professor, Department of Plant Pathology, University of Arkansas, Fayetteville, 72701; E. M. Flores, associate professor, Centro de Investigación en Biología Celular y Molecular, Universidad de Costa Rica, San José. Phytopathology 69:980-984. Accepted for publication 26 March 1979. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-980.

The nuclear ultrastructure was significantly changed in cells of Euphorbia heterophylla naturally infected with the whitefly-transmitted Euphorbia mosaic virus in Costa Rica. Hypertrophy of the nucleolus, segregation of the granular and fibrillar regions of the nucleolus, and appearance of fibrillar rings and virus particles occurred. Infected cells were restricted to the phloem, and virus particles occurred only in the nucleus and lumen of mature sieve elements. These changes were very similar to those observed in cells infected with bean golden mosaic virus, another whitefly-transmitted virus containing a single-stranded DNA genome.