title: Three seedborne cryptic viruses containing double-stranded RNA isolated from white clover.
abstract: White clover cryptic viruses (WCCV) 1, 2, and 3 were purified from apparently healthy plants with yields of about 200 mug of virus/kg of tissue. After isopycnic centrifugation in CsCl, WCCV 1 and 2 formed homogeneous bands at densities of 1.392 and 1.375 g/ml, respectively, whereas WCCV 3 was not recovered. Particles of WCCV 1 and 3 were 34 nm in diameter, without obvious morphological subunits, whereas WCCV 2 particles were 38 nm in diameter, with prominent morphological subunits. Antisera with titers up to 1:2048 were obtained against WCCV 1 and 2. Each of the three viruses contained two segments of linear dsRNA (Mr from 1.03 to 1.49 X 10(-6). Virus-like particles, probably those of WCCV 1 and 2 were detected in low numbers in the cytoplasm of about 1/10 of the parenchyma cells of carrier plants examined by thin sectioning. The particles of WCCV 1 and 2 were not transmitted by grafting or mechanical inoculation, but were seed transmitted. Evidence is given that WCCV 1 and 2 multiply in their carrier plants, and are not viruses of associated parasitic or commensal organisms.
authors.affiliation: Istituto di Fitovirologia applicator del C.N.R., via O. Vigliani 104, 10135 Torino, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Boccardo
authors.forename: R G
authors.initials: RG
authors.lastname: Milne
authors.forename: E
authors.initials: E
authors.lastname: Luisoni
authors.forename: V
authors.initials: V
authors.lastname: Lisa
authors.forename: G P
authors.initials: GP
authors.lastname: Accotto