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Type Species |
(HSVd) |
A circular ssRNA of 295-303 bases depending on isolates and sequence variants. The most stable secondary structure is a rod-like or quasi-rod-like conformation with five domains, a central conserved region (CCR) similar to that of pospi- and cocadviroids, and a terminal conserved hairpin (TCH) (Fig. 2). Replication occurs through an asymmetric rolling-circle model since longer-than-unit minus strands have been found in infected tissue (Fig. 3). It seems to be unique from the standpoint of the biological properties because it infects a very broad range of natural hosts and, therefore, is distributed worldwide.
List of Species Demarcation Criteria in the Genus
Not applicable.
Official viroid species names are in italics. Tentative names, alternative names ( ), or strains are not italicized. Viroid names, CMI/AAB description numbers ( ), genomic accession numbers of typical sequence variants [ ], sizes {b}, and assigned abbreviations ( ) are:
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Hop stunt viroid (326)† |
[X00009] |
{295-303} |
(HSVd) |
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(Citrus cachexia viroid) |
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(Cucumber pale fruit viroid) |
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(Plum dapple viroid) |
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(Peach dapple viroid) |
† Agent isolated from grapevine, pear, apricot, banana, raspberry, hibiscus and croton (Codiaeum).
Tentative Species in the Genus
None reported.
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