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Submitted to: Plant Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/14/2014 Publication Date: 5/21/2014 Citation: Kovalskaya, N.Y., Hammond, R. 2014. Molecular biology of viroid-host interactions and disease control strategies. Plant Science. DOI:10.1016/jplantsci.2014.05.006. Interpretive Summary: Viroids are small, noncoding RNAs and are important pathogens of food, industrial and ornamental plants. While control can be achieved for several viroid diseases by eradication and replanting, and the use of heat or cryotherapy combined with meristem tip culture to produce viroid-free germplasm, naturally occurring resistance has not been identified in most host species. Biotechnological approaches for controlling viroid diseases have been investigated and include the engineering of viroid resistance into host species using basic knowledge of viroid biology. The results of those efforts and the challenges associated with creating viroid resistant plants are summarized in this review. These results will be of interest to scientists who are developing novel plant disease control strategies. Technical Abstract: 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. Current effective control methods for viroid diseases include detection and eradication and cultural controls. While there are non-hosts for viroids, no naturally occurring durable resistance has been observed in most host species. The phenomenon of cross-protection exists in viroids, where prior infection of a host with one viroid or viroid strain can protect the infected plant from subsequent infection by another viroid or viroid strain. 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. |
