Comparative Cytology of Two Isolates of Cauliflower Mosaic Virus

Abstract

SUMMARY The cytology of Cabb-S and Cabb-D/H isolates of cauliflower mosaic virus (CaMV) was compared by electron microscopy. In turnips (Brassica rapa L. cv. ‘Just Right’) the two strains induced similar symptoms. In the Cabb-S infected cells the viroplasms contain large amounts of electron-dense material and small amounts of virions, in contrast to the Cabb-D/H-infected cells where there are large amounts of virions and less electron-dense material. The viroplasms could be detected 3 days after inoculation with the Cabb-S isolate but only after 6 days in the leaves infected with the Cabb-D/H isolate. Another type of inclusion, intensely stained using Bernhard’s EDTA technique, was detected in the cells infected with either isolate about 10 days after inoculation. The significance of these cytoplasmic areas, which coexist with well-developed viroplasms, is discussed.