CHARACTERIZATION OF GENOME STRUCTURE AND ESTABLISHMENT OF VECTOR CELL-LINES FOR PLANT REOVIRUSES

Plant reoviruses are a unique group among plant pathogenic viruses. They are members of a family that includes viruses of both vertebrates and invertebrates, and all members share characteristic features: (1) they are leafhopper and planthopper borne in a persistent manner, (2) they contain spherical particles 60-70 nm in diameter, and (3) their genomes consist of 10-12 segmented double-stranded RNAs (dsRNAs). The classical study of plant reoviruses that attracted the attention of researchers focuses chiefly on the multiplication of the plant pathogenic viruses in their insect vectors, starting with Fukushi's finding in 1940, based on his spectacular experimental evidence that rice dwarf virus (RDV) multiplied in its insect vector; this finding later promoted “controversial discussions”. Subsequently, further evidence based on biological and electron microscopic studies fully supported Fukushi's discovery. Among the plant reoviruses, RDV and wound tumor virus (WTV) have been most extensively studied, with respect to their insect transmission, transovarial passage, virus particles, localization of the viruses in their plant and insect hosts, establishment of cell lines from embryonic tissue culture of the respective insect vectors, and genome characterization. This chapter reviews the recent findings concerning dsRNA genomes of plant reoviruses, especially the detailed characterization of all 12 genomic segments of RDV achieved in Japan. This is the first report of a successful genomic analysis of the 12 segmented dsRNAs of a virus belonging to the plant reoviruses. © 1995, Academic Press Inc.