VIEW ARTICLE

Intracellular Morphology of Two Tobacco Mosaic Virus Strains in, and Cytological Responses of, Systemically Susceptible Potato Plants. Kang- chien Liu, Former Graduate Assistant, Department of Plant Pathology, The Pennsylvania State University, University Park 16802; John S. Boyle, Professor, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. Phytopathology 62:1303-1311. Accepted for publication 24 May 1972. DOI: 10.1094/Phyto-62-1303.

Comparative studies were made to investigate the intracellular behavior of two strains of tobacco mosaic virus which cause distinctly different symptoms in systemically infected potato plants. In cells of these plants, which were derived as clonal material from selected susceptible seedlings, both U-1 and a yellow strain formed hexagonal crystals in infected cells. The yellow strain caused degradation of chloroplasts which was correlated with yellowing of leaves and the presence of many osmiophilic globules in the cytoplasm. In cells infected with the U-1 strain, filamentous tubes and microcrystals were found. The phenomenon that different strains of a virus cause distinct cytological responses, which correlate to the external symptoms, yet form almost similar intracellular viral crystals and aggregates, would be explained by the two strains having different genes governing cytological effects and identical genes controlling synthesis of coat protein. The evidence that microcrystals were found only in cells infected with the U-1 strain but not in cells infected with the yellow strain implies that, apparently, different host-virus interactions operate in genetically identical cells of the host.