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Etiology

Comparison of a New Soilborne Virus from Cucumber with Tombus-, Diantho-, and Other Similar Viruses. R. Koenig, Institut für Viruskrankheiten der Pflanzen der Biologischen Bundesanstalt für Land- und Forstwirtschaft, Messeweg 11, D-3300 Braunschweig, Federal Republic of Germany (R. K., D.-E. L., and W. H.); D.-E. Lesemann(2), W. Huth(3), and K. M. Makkouk(4). (2)(3)(4)National Council for Scientific Research/Faculty of Agricultural and Food Sciences, American University of Beirut, Beirut, Lebanon (K. M. M.). Phytopathology 73:515-520. Accepted for publication 29 September 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-515.

A virus isolated from cucumber roots grown in soil from the Jiyeh area south of Beirut produced local lesions on a number of plant species, but no systemic infections. Its particles with a diameter of ~31 nm had a sedimentation coefficient of ~120S and a buoyant density in CsCl of 1.343 g/cm³, indicating an RNA content of ~18%. Its UV absorption spectrum had a minimum at 245 nm and a maximum at 260 nm. In immunoelectrophoresis at pH 7.0, the virus migrated towards the anode. The viral coat protein and the single genomic RNA species had molecular weights of 4.14 × 10⁴ and 1.5 × 10⁶, respectively. Some preparations also contained a minor RNA species with a molecular weight of 0.16- 0.19 × 10⁶, which was not necessary for infection. The base composition of the RNA was C22, A23, G32, and U23. Virus particles were found scattered or in small aggregates in the cytoplasm, but not in nuclei or other organelles. The virus did not induce cytopathic effects typical of tombusviruses or dianthoviruses, nor did it react with antisera to known tombusviruses, dianthoviruses, or 43 other isometric viruses. Cucumber soilborne virus is the name proposed for this apparently newly described virus.