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Etiology

Properties of Tobacco Yellow Dwarf and Bean Summer Death Viruses. J. E. Thomas, Plant pathologist, Department of Primary Industries, Meiers Road, Indooroopilly, Queensland, Australia 4068; J. W. Bowyer, lecturer, Department of Plant Pathology and Agricultural Entomology, University of Sydney, N.S.W., Australia 2006. Phytopathology 70:214-217. Accepted for publication 28 August 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-214.

Tobacco yellow dwarf and bean summer death diseases apparently are confined to Australia, and the causal pathogens are transmitted by the leafhopper Orosius argentatus. The diseases were shown to be caused by viruses. Purified preparations obtained from Datura stramonium plants, infected with either tobacco yellow dwarf virus (TYDV) or bean summer death virus (BSDV), contained viruslike particles occurring in pairs about 20 nm × 35 nm in size. On sedimentation in sucrose density gradients, the geminate particles of TYDV and BSDV each formed discrete zones which were associated with infectivity. TYDV preparations have an ultraviolet absorbance typical of a nucleoprotein, contain a single centrifugal component with a sedimentation coefficient of 76S, and yield a single structural protein species of molecular weight 27,500. The yield of TYDV was about 100–250 μg/kg of tissue, and of BSDV about 20–50 μg/kg of tissue. In addition to producing similar host reactions and having similar vector relations, TYDV and BSDV are serologically related, and are therefore considered likely to be strains of one virus. TYDV and BSDV have many properties in common with beet curly top virus (CTV), and a distant serological relationship was established between TYDV and CTV.