Abstract
Introduction. Most plant viruses contain an RNA genome and are traditionally classified into genera (or families) of which there are over 40. This large number reflects the formidable variety that exists among plant RNA viruses. The genomes are mostly single-stranded (ss) and of positive polarity; in a few genera, they are negative sense, ambisense, or double-stranded (ds).
The different strategies used by viruses for their amplification have been described at length. However, it is often difficult to find in a summarized form the main data on genome features of all groups of plant RNA viruses. The last review article along these lines (Davies & Hull, 1982) dates from before any full-length RNA sequence of a plant RNA virus was published; never-theless, a few books have more recently included this subject (Francki et al., 1991; Matthews, 1991).
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