Emerging value of the viroid model in molecular biology and beyond

• Published in: Virus research Vol. 313; p. 198730
• Main Authors: Ma, Junfei, Mudiyanselage, Shachinthaka D. Dissanayaka, Wang, Ying
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.05.2022; Elsevier
• Subjects: Molecular Biology; Plant Diseases - genetics; Plant innate immunity; Plants; Pol II; RNA trafficking; RNA, Viral - chemistry; RNA, Viral - genetics; RNA-templated transcription; Viroid; Viroids - genetics; RNA-templated transcription; Pol II; Plant innate immunity; RNA trafficking; Viroid
• ISSN: 0168-1702; 1872-7492; 1872-7492
• DOI: 10.1016/j.virusres.2022.198730

•This review reasons the value of viroid model for studying RNA-templated transcription, RNA structures, and plant immunity.•This review outlines some unresolved yet significant questions in viroid biology and provides testable hypotheses. Viroids are single-stranded circular noncoding RNAs that infect plants. Research in the past five decades has deciphered the viroid genome structures, viroid replication cycles, numerous host factors for viroid infection, viroid motifs for intracellular and intercellular trafficking, interactions with host defense machinery, etc. In this review, we mainly focus on some significant questions that remain to be tackled, centered around (1) how the RNA polymerase II machinery performs transcription on RNA templates of nuclear-replicating viroids, (2) how viroid RNAs coordinate multiple structural elements for diverse functions, and (3) how viroid RNAs activate plant immunity. Research on viroids has led to seminal discoveries in biology, and we expect the research directions outlined in this review to continue providing key knowledge inspiring other areas of biology.