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A New Type of Elongated Virus Isolated from Apple Trees Containing the Stem Pitting Agent. H. Koganezawa, Morioka Branch, Fruit Tree Research Station, Shimokuriyagawa, Morioka 020-01, Japan. H. Yanase, Fruit Tree Research Station, Fujimoto, Tsukuba 305, Japan. Plant Dis. 74:610-614. Accepted for publication 16 December 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0610.

A flexuous, filamentous virus was always transmitted by mechanical inoculation to Nicotiana occidentalis from apple trees infected with the agent, causing apple stem pitting disease. A virus with particles 1215 nm wide and 800 nm long was purified from infected N. occidentalis leaves. The virus particles readily formed end-to-end aggregates. Prominent peaks in particle length distribution of 800, 1,600, 2,400, and 3,200 nm were observed in leaf dip preparations of diseased N. occidentalis subsp. obliqua. The particles contained a single species of RNA of Mr 3.1 106 and a major coat protein of Mr 48,000. The virus particles were found in the cytoplasm of mesophyll cells. These data suggest that the virus does not fall into any recognized group of plant viruses.