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Morphological Comparisons of Echinochloa Ragged Stunt and Rice Ragged Stunt Viruses by Electron Microscopy. C. C. Chen, Plant pathologist, Taichung District Agricultural Improvement Station, Changhua 515, Taiwan; M. J. Chen(2), R. J. Chiu(3), and H. T. Hsu(4). (2)Professor of plant pathology, Department of Plant Pathology, National Chung-Hsing University, Taichung 400, Taiwan; (3)Senior plant pathologist, Council of Agriculture, Taipei 107, Taiwan; (4)Research microbiologist, Florist and Nursery Crops Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705. Phytopathology 79:235-241. Accepted for publication 30 August 1988. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1989. DOI: 10.1094/Phyto-79-235.

The morphological characters of Echinochloa ragged stunt virus (ERSV) and rice ragged stunt virus (RRSV) were compared by electron microscopy. Virions in negatively stained purified samples and dip preparations from leaves of Echinochloa crus-galli var. oryzicola infected with ERSV were 54-58 nm in diameter. Smaller B-spiked particles, 50 nm in diameter, were observed in purified preparations. Hexagonal particles measuring 72 nm in diameter, with A-spike projections, were present occasionally in crude dips prepared from glutaraldehyde-fixed leaves. In ultrathin sections of ERSV-infected plant tissues, particles 60-70 nm in diameter with densely stained cores occurred along the outer membranes of mesophyll chloroplasts and in viroplasms of phloem parenchyma cells. Particles approximately 55-75 nm in diameter were found in thin sections of cytoplasm of cells of the salivary gland, fat body, gut, brain, gastric caeca, and ommatidia cornea cells of the compound eye of viruliferous ERSV vectors, Sogatella longifurcifera. Purified RRSV consisted mostly of 55-nm-diameter subviral particles. Particles 62-66 nm in diameter were observed only in crude sap preparations of infected rice leaves fixed with glutaraldehyde. Particles of two different sizes, 40 nm and 55-70 nm in diameter, were scattered in the viroplasm in phloem cells of RRSV-infected rice plants. In thin sections of the viruliferous RRSV vector, Nilaparvata lugens, particles of 60-75 nm were found in the cytoplasm of salivary gland, fat body, seminal vescle, gut, and muscle cells.

Additional keywords: fijivirus, Oryza sativa, reoviridae, ultrastructure.