Detection and characterization of viroids via biological assays on herbaceous hosts

Authors: Hammond, Rosemarie

Submitted to: Methods in Molecular Biology
Publication Type: Book / Chapter
Publication Acceptance Date: 7/9/2020
Publication Date: 11/30/2021
Citation: Hammond, R. 2021. Detection and characterization of viroids via biological assays on herbaceous hosts. Methods in Molecular Biology. 2316:23-28. https://doi.org/10.1007/978-1-0716-1464-8_2.
DOI: https://doi.org/10.1007/978-1-0716-1464-8_2

Interpretive Summary: Viroids are the smallest known infectious agents of plant diseases and are pathogens of food, industrial, and ornamental plants worldwide. Yield losses caused by viroids (small noncoding circular infectious RNAs) can reach 17-64% depending on the viroid strain and plant crop species. Sequence characterization of known and newly discovered viroids is critical to disease management and global trade. In this chapter, methods are described for mechanical inoculation of viroids to herbaceous hosts to determine the viroid nature of diseases, the experimental host range of the viroid or to shorten the time required for obtaining relatively large amounts of viroid for subsequent purification and characterization. It is intended as a reference for beginners in the field. This work will be of value to an international audience of researchers in industry, academia, and government organizations with an interest in plant pathology and virology and the detection and control of plant diseases.

Technical Abstract: The characterization of the elusive disease agent of the potato spindle tuber disease, potato spindle tuber viroid (PSTVd), was aided by the ability to obtain large amounts of infected tomato tissue in a simple bioassay where PSTVd was easily mechanically transmissible to an alternate herbaceous host in which it thrived and produced dramatic symptoms in a relatively short period. Reactions in the primary, or secondary, herbaceous indicator host can range from asymptomatic to severe depending upon the viroid strain, host species, and environmental conditions and can provide evidence of a viroid infection, but does not permit identification of the viroid in question. Further characterization by molecular hybridization, RT-PCR and sequence analysis is used to determine the etiology of the disease agent. In this chapter, methods are described for mechanical inoculation of viroids to herbaceous hosts to determine the viroid nature of diseases, the experimental host range of the viroid or to shorten the time required for obtaining relatively large amounts of viroid for subsequent purification and characterization.