Molecular biology of viroid–host interactions and disease control strategies

•Many host-plants lack natural resistance to viroid infection.•Host factors play a key role in viroid spread and pathogenicity.•Unlike mature viroid RNA, viroid intermediates are susceptible to RNA silencing machinery.•Molecular approaches to introduce resistance to viroids are promising and require...

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Bibliographic Details
Published in:Plant science (Limerick) 2014-11, Vol.228, p.48-60
Main Authors: Kovalskaya, Natalia, Hammond, Rosemarie W.
Format: Article
Language:English
Subjects:
Disease Resistance
dsRNA
Host-Pathogen Interactions
Plant Diseases - immunology
Plant Diseases - prevention & control
Plants - virology
Resistance
Ribonuclease
Ribozyme
siRNA
Viroids
Viroids - physiology
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Summary:•Many host-plants lack natural resistance to viroid infection.•Host factors play a key role in viroid spread and pathogenicity.•Unlike mature viroid RNA, viroid intermediates are susceptible to RNA silencing machinery.•Molecular approaches to introduce resistance to viroids are promising and require further development. Viroids are single-stranded, covalently closed, circular, highly structured noncoding RNAs that cause disease in several economically important crop plants. They replicate autonomously and move systemically in host plants with the aid of the host machinery. In addition to symptomatic infections, viroids also cause latent infections where there is no visual evidence of infection in the host; however, transfer to a susceptible host can result in devastating disease. While there are non-hosts for viroids, no naturally occurring durable resistance has been observed in most host species. Current effective control methods for viroid diseases include detection and eradication, and cultural controls. In addition, heat or cold therapy combined with meristem tip culture has been shown to be effective for elimination of viroids for some viroid–host combinations. An understanding of viroid–host interactions, host susceptibility, and non-host resistance could provide guidance for the design of viroid-resistant plants. Efforts to engineer viroid resistance into host species have been underway for several years, and include the use of antisense RNA, antisense RNA plus ribozymes, a dsRNase, and siRNAs, among others. The results of those efforts and the challenges associated with creating viroid resistant plants are summarized in this review.
ISSN:0168-9452
1873-2259
DOI:10.1016/j.plantsci.2014.05.006