Summary: A group of pathogens comprising the smallest known agents of infectious disease. They are unencapsulated and are capable of replicating autonomously in susceptible cells. Positively identified viroids composed of single-stranded RNA have been isolated from higher plants, but the existence of DNA viroids pathogenic to animals is suspected.

Top Publications

  1. Carbonell A, Martinez de Alba A, Flores R, Gago S. Double-stranded RNA interferes in a sequence-specific manner with the infection of representative members of the two viroid families. Virology. 2008;371:44-53 pubmed
    Infection by viroids, non-protein-coding circular RNAs, occurs with the accumulation of 21-24 nt viroid-derived small RNAs (vd-sRNAs) with characteristic properties of small interfering RNAs (siRNAs) associated to RNA silencing...
  2. Qi Y, Ding B. Inhibition of cell growth and shoot development by a specific nucleotide sequence in a noncoding viroid RNA. Plant Cell. 2003;15:1360-74 pubmed
    b>Viroids are small noncoding and infectious RNAs that replicate autonomously and move systemically throughout an infected plant...
  3. Gora Sochacka A. Viroids: unusual small pathogenic RNAs. Acta Biochim Pol. 2004;51:587-607 pubmed
    b>Viroids are small (about 300 nucleotides), single-stranded, circular, non-encapsidated pathogenic RNA molecules. They do not code for proteins and thus depend on plant host enzymes for their replication and other functions...
  4. Diener T. Origin and evolution of viroids and viroid-like satellite RNAs. Virus Genes. 1995;11:119-31 pubmed
    b>Viroids, the smallest and simplest agents of infectious disease, cause a number of economically important diseases of crop plants...
  5. Vidal A, Ben Cheikh W, Talon M, Garcia Martinez J. Regulation of gibberellin 20-oxidase gene expression and gibberellin content in citrus by temperature and citrus exocortis viroid. Planta. 2003;217:442-8 pubmed
    ..The results also show that the growth reduction induced by environmental (temperature) and biotic (CEVd) factors may be partially due to the modulation of the expression of GA20ox genes. ..
  6. Wang Y, Ding B. Viroids: small probes for exploring the vast universe of RNA trafficking in plants. J Integr Plant Biol. 2010;52:28-39 pubmed publisher
    ..We then focus our discussion on research findings obtained using viroids that have advanced our understanding of the underlying mechanisms involved in RNA trafficking...
  7. Spieker R. In vitro-generated 'inverse' chimeric Coleus blumei viroids evolve in vivo into infectious RNA replicons. J Gen Virol. 1996;77 ( Pt 11):2839-46 pubmed
    The three Coleus blumei viroids (CbVd) CbVd 1-RL, CbVd 2-RL and CbVd 3-RL occur naturally in plants of Coleus blumei cultivar (cv.) 'Ruhm von Luxemburg'...
  8. Tsagris E, Martinez de Alba A, Gozmanova M, Kalantidis K. Viroids. Cell Microbiol. 2008;10:2168-79 pubmed publisher
    b>Viroids are small, circular RNA pathogens, which infect several crop plants and can cause diseases of economic importance...
  9. Diener T. Discovering viroids--a personal perspective. Nat Rev Microbiol. 2003;1:75-80 pubmed
    ..b>Viroids are so small--one fiftieth of the size of the smallest viruses--that many scientists initially doubted their ..

More Information

Publications116 found, 100 shown here

  1. Martinez G, Donaire L, Llave C, Pallas V, Gomez G. High-throughput sequencing of Hop stunt viroid-derived small RNAs from cucumber leaves and phloem. Mol Plant Pathol. 2010;11:347-59 pubmed publisher
    ..b>Viroids, the smallest self-replicating plant pathogens known, are inducers, targets and evaders of this regulatory ..
  2. Xu W, Bolduc F, Hong N, Perreault J. The use of a combination of computer-assisted structure prediction and SHAPE probing to elucidate the secondary structures of five viroids. Mol Plant Pathol. 2012;13:666-76 pubmed publisher
    The elucidation of the structures of viroids, noncoding infectious RNA species, is paramount to obtain an understanding of the various aspects of their life cycles (including replication, transport and pathogenesis)...
  3. Wu Q, Wang Y, Cao M, Pantaleo V, Burgyan J, Li W, et al. Homology-independent discovery of replicating pathogenic circular RNAs by deep sequencing and a new computational algorithm. Proc Natl Acad Sci U S A. 2012;109:3938-43 pubmed publisher
    ..Here we report a homology-independent approach for discovering viroids, a distinct class of free circular RNA subviral pathogens that encode no protein and are known to infect plants ..
  4. Matousek J, Orctova L, Ptacek J, Patzak J, Dedic P, Steger G, et al. Experimental transmission of pospiviroid populations to weed species characteristic of potato and hop fields. J Virol. 2007;81:11891-9 pubmed potential hosts that could transmit and lead to spreading of potato spindle tuber (PSTVd) and hop stunt (HSVd) viroids, respectively...
  5. Wang Y, Shibuya M, Taneda A, Kurauchi T, Senda M, Owens R, et al. Accumulation of Potato spindle tuber viroid-specific small RNAs is accompanied by specific changes in gene expression in two tomato cultivars. Virology. 2011;413:72-83 pubmed publisher
    ..Of 18 such genes down-regulated early in infection, two genes involved in gibberellin or jasmonic acid biosynthesis contain binding sites for PSTVd small RNAs in their respective ORFs. ..
  6. Torchetti E, Navarro B, Di Serio F. A single polyprobe for detecting simultaneously eight pospiviroids infecting ornamentals and vegetables. J Virol Methods. 2012;186:141-6 pubmed publisher
    The spread of viroids belonging to the genus Pospiviroid (family Pospiviroidae), recorded recently in ornamentals and vegetables in several European countries, calls for fast, efficient and sensitive detection methods...
  7. Tornero P, Conejero V, Vera P. A gene encoding a novel isoform of the PR-1 protein family from tomato is induced upon viroid infection. Mol Gen Genet. 1994;243:47-53 pubmed
    ..Comparative studies of this gene and a related basic isoform of PR-1 indicate that the expression of these two members of the PR-1 gene family in tomato may be differentially regulated upon viroid infection. ..
  8. Martinez de Alba A, Sägesser R, Tabler M, Tsagris M. A bromodomain-containing protein from tomato specifically binds potato spindle tuber viroid RNA in vitro and in vivo. J Virol. 2003;77:9685-94 pubmed
    ..VIRP1 is the first member of this family of proteins, for which a specific RNA-binding activity is shown. A possible role of VIRP1 in viroid replication and in RNA mediated chromatin remodeling is discussed. ..
  9. Gago S, de la Peña M, Flores R. A kissing-loop interaction in a hammerhead viroid RNA critical for its in vitro folding and in vivo viability. RNA. 2005;11:1073-83 pubmed
    ..In contrast to most other viroids, which adopt rod-like or quasi-rod-like secondary structures of minimal free energy, the computer-predicted ..
  10. Gora Sochacka A, Kierzek A, Candresse T, Zagorski W. The genetic stability of potato spindle tuber viroid (PSTVd) molecular variants. RNA. 1997;3:68-74 pubmed
    ..Although it has been observed previously that artificially mutated PSTVd molecules may revert rapidly to the wild-type sequence, this study presents direct evidence for the rapid evolution of naturally occurring PSTVd sequence variants. ..
  11. Weinberg M, Rossi J. Comparative single-turnover kinetic analyses of trans-cleaving hammerhead ribozymes with naturally derived non-conserved sequence motifs. FEBS Lett. 2005;579:1619-24 pubmed
  12. Sipahioglu H, Usta M, Ocak M. Use of dried high-phenolic laden host leaves for virus and viroid preservation and detection by PCR methods. J Virol Methods. 2006;137:120-4 pubmed
    ..The RNA derived from dry leaf samples was suitable for detection studies. This simple and inexpensive method has proved very effective for long term conservation of virus and viroid isolates. ..
  13. Matousek J, Kozlov P, Orctov L, Schmitz A, Pesina K, Bannach O, et al. Accumulation of viroid-specific small RNAs and increase in nucleolytic activities linked to viroid-caused pathogenesis. Biol Chem. 2007;388:1-13 pubmed publisher
    ..The vascular-specific pathogenesis action is supported by light microscopic observations demonstrating a certain lack of xylem tissue and an arrest of the establishment of new vascular bundles in collapsed plants...
  14. Gomez G, Martinez G, Pallas V. Interplay between viroid-induced pathogenesis and RNA silencing pathways. Trends Plant Sci. 2009;14:264-9 pubmed publisher
    Of all known plant pathogens, viroids have the lowest biological complexity. Their genome consists of a naked RNA without protein-encoding capacity...
  15. Di Serio F, Martinez de Alba A, Navarro B, Gisel A, Flores R. RNA-dependent RNA polymerase 6 delays accumulation and precludes meristem invasion of a viroid that replicates in the nucleus. J Virol. 2010;84:2477-89 pubmed publisher
  16. Fekih Hassen I, Massart S, Motard J, Roussel S, Parisi O, Kummert J, et al. Molecular features of new Peach Latent Mosaic Viroid variants suggest that recombination may have contributed to the evolution of this infectious RNA. Virology. 2007;360:50-7 pubmed
    ..PLMVd thus emerges as a suitable viroid for retracing the evolution of an RNA genome. ..
  17. Ding B, Kwon M, Hammond R, Owens R. Cell-to-cell movement of potato spindle tuber viroid. Plant J. 1997;12:931-6 pubmed
    b>Viroids are non-translatable, autonomously replicating circular RNAs that infect only plants...
  18. Zhong X, Leontis N, Qian S, Itaya A, Qi Y, Boris Lawrie K, et al. Tertiary structural and functional analyses of a viroid RNA motif by isostericity matrix and mutagenesis reveal its essential role in replication. J Virol. 2006;80:8566-81 pubmed
    ..Specific RNA motifs likely regulate various aspects of this replication. Viroids of the Pospiviroidae family, as represented by the Potato spindle tuber viroid (PSTVd), replicate in the nucleus ..
  19. Owens R, Baumstark T. Structural differences within the loop E motif imply alternative mechanisms of viroid processing. RNA. 2007;13:824-34 pubmed
    b>Viroids replicate via a rolling circle mechanism, and cleavage/ligation requires extensive rearrangement of the highly base-paired native structure...
  20. Sano T, Isono S, Matsuki K, Kawaguchi Ito Y, Tanaka K, Kondo K, et al. Vegetative propagation and its possible role as a genetic bottleneck in the shaping of the apple fruit crinkle viroid populations in apple and hop plants. Virus Genes. 2008;37:298-303 pubmed publisher
    ..In this scenario, a genetic bottleneck caused by vegetative propagation played an important role in the shaping of viroid populations in a cultivated crop. ..
  21. Martínez de Alba A, Flores R, Hernandez C. Two chloroplastic viroids induce the accumulation of small RNAs associated with posttranscriptional gene silencing. J Virol. 2002;76:13094-6 pubmed
    ..Here we show that viroids that replicate and accumulate in the chloroplast are also targets of PTGS and this process may control viroid ..
  22. Landry P, Perreault J. Identification of a peach latent mosaic viroid hairpin able to act as a Dicer-like substrate. J Virol. 2005;79:6540-3 pubmed
    The ability of several viroids to induce posttranscriptional gene silencing has been demonstrated; however, the structure recognized by the Dicer enzyme(s) responsible for the initiation of this mechanism remains a mystery...
  23. Wang Y, Zhong X, Itaya A, Ding B. Evidence for the existence of the loop E motif of Potato spindle tuber viroid in vivo. J Virol. 2007;81:2074-7 pubmed
    ..By using UV cross-linking and primer extension, we have obtained direct evidence for the in vivo existence of the loop E motif of Potato spindle tuber viroid. We present our findings and discuss their biological implications. ..
  24. Codoñer F, Daròs J, Sole R, Elena S. The fittest versus the flattest: experimental confirmation of the quasispecies effect with subviral pathogens. PLoS Pathog. 2006;2:e136 pubmed
    ..In contrast, the slow-growth species was able to outcompete the fast species when the mutation rate was increased. These experimental results were supported by an in silico model of competing viroid quasispecies. ..
  25. Nie X, Singh R. A novel usage of random primers for multiplex RT-PCR detection of virus and viroid in aphids, leaves, and tubers. J Virol Methods. 2001;91:37-49 pubmed
    ..Comparison of RP primed cDNAs from dormant or sprouted tubers and leaves showed that for some cultivars, such as 'Shepody', leaves were more reliable for PVY and PLRV detection than the tubers, in both the d- and m-RT-PCR. ..
  26. Schrader O, Baumstark T, Riesner D. A mini-RNA containing the tetraloop, wobble-pair and loop E motifs of the central conserved region of potato spindle tuber viroid is processed into a minicircle. Nucleic Acids Res. 2003;31:988-98 pubmed
    ..Hence all three structural motifs are functional elements for processing in a potato nuclear extract. ..
  27. Bernad L, Duran Vila N. A novel RT-PCR approach for detection and characterization of citrus viroids. Mol Cell Probes. 2006;20:105-13 pubmed
    ..Because of their small size, viroids lend themselves to various RT-PCR approaches for their detection and further characterization...
  28. Pelchat M, Rocheleau L, Perreault J, Perreault J. SubViral RNA: a database of the smallest known auto-replicable RNA species. Nucleic Acids Res. 2003;31:444-5 pubmed
    ..We describe here the establishment of an online database containing a large number of sequences and related data on viroids, viroid-like RNAs and human hepatitis delta virus (vHDV) in a customizable and user-friendly format...
  29. Rodio M, Delgado S, Flores R, Di Serio F. Variants of Peach latent mosaic viroid inducing peach calico: uneven distribution in infected plants and requirements of the insertion containing the pathogenicity determinant. J Gen Virol. 2006;87:231-40 pubmed
    ..Insertions can be acquired and lost during infection, suggesting that latent variants can evolve into pathogenic variants and vice versa...
  30. Diermann N, Matousek J, Junge M, Riesner D, Steger G. Characterization of plant miRNAs and small RNAs derived from potato spindle tuber viroid (PSTVd) in infected tomato. Biol Chem. 2010;391:1379-90 pubmed publisher
    ..Also viroids - plant infectious, non-coding, unencapsidated RNA - cause the production of viroid-specific small RNAs (vsRNA), ..
  31. Ding B, Wang Y. Viroids: uniquely simple and tractable models to elucidate regulation of cell-to-cell trafficking of RNA. DNA Cell Biol. 2009;28:51-6 pubmed publisher
    ..Here we discuss the unique features of viroids as well as experimental data to demonstrate these RNAs as simple and highly tractable models to elucidate the ..
  32. Herranz M, Niehl A, Rosales M, Fiore N, Zamorano A, Granell A, et al. A remarkable synergistic effect at the transcriptomic level in peach fruits doubly infected by prunus necrotic ringspot virus and peach latent mosaic viroid. Virol J. 2013;10:164 pubmed publisher
  33. Candresse T, Macquaire G, Monsion M, Dunez J. Detection of Chrysanthemum stunt viroid (CSV) using nick translated probes in a dot-blot hybridization assay. J Virol Methods. 1988;20:185-93 pubmed
    ..Under these conditions, 100 pg of pure viroid diluted in plant sap, or infected plant extract diluted 1:25 in healthy extract can be detected, showing the potential of this method for indexing of Chrysanthemum for CSV infection. ..
  34. Qi Y, Pélissier T, Itaya A, Hunt E, Wassenegger M, Ding B. Direct role of a viroid RNA motif in mediating directional RNA trafficking across a specific cellular boundary. Plant Cell. 2004;16:1741-52 pubmed
    ..Selected endogenous RNAs, viral RNAs, and viroids traffic between specific cells or organs via this network...
  35. Cohen O, Batuman O, Stanbekova G, Sano T, Mawassi M, Bar Joseph M. Construction of a multiprobe for the simultaneous detection of viroids infecting citrus trees. Virus Genes. 2006;33:287-92 pubmed
    ..common among cultivated fruit trees and grapevines, and many old-clone citrus varieties contain up to five citrus viroids (CVds) within a single tree...
  36. St Pierre P, Hassen I, Thompson D, Perreault J. Characterization of the siRNAs associated with peach latent mosaic viroid infection. Virology. 2009;383:178-82 pubmed publisher
    ..the more highly structured regions of PLMVd trigger the activity of the Dicer-like enzymes; and, iii. the circular PLMVd conformers appear to be favored for transport into the cytoplasm. ..
  37. Murcia N, Serra P, Olmos A, Duran Vila N. A novel hybridization approach for detection of citrus viroids. Mol Cell Probes. 2009;23:95-102 pubmed publisher
    ..Previous attempts to detect viroids from field-grown species and cultivars yielded erratic results unless analyses were performed using Etrog citron ..
  38. Navarro B, Pantaleo V, Gisel A, Moxon S, Dalmay T, Bisztray G, et al. Deep sequencing of viroid-derived small RNAs from grapevine provides new insights on the role of RNA silencing in plant-viroid interaction. PLoS ONE. 2009;4:e7686 pubmed publisher
    b>Viroids are circular, highly structured, non-protein-coding RNAs that, usurping cellular enzymes and escaping host defense mechanisms, are able to replicate and move through infected plants...
  39. de la Pena M, Flores R. An extra nucleotide in the consensus catalytic core of a viroid hammerhead ribozyme: implications for the design of more efficient ribozymes. J Biol Chem. 2001;276:34586-93 pubmed
    ..Incorporation of the extra U10 into a model hammerhead also caused a similar increase in the rate constant, providing data for a deeper understanding of the hammerhead structural requirements and for designing more efficient ribozymes. ..
  40. Boonham N, Pérez L, Mendez M, Peralta E, Blockley A, Walsh K, et al. Development of a real-time RT-PCR assay for the detection of potato spindle tuber viroid. J Virol Methods. 2004;116:139-46 pubmed
    ..relevant to the efficient amplification of targets that have a significant amount of secondary structure such as viroids. Thus comparisons were made of reverse transcription temperature, concentration and type of reverse transcriptase,..
  41. Zhong X, Archual A, Amin A, Ding B. A genomic map of viroid RNA motifs critical for replication and systemic trafficking. Plant Cell. 2008;20:35-47 pubmed publisher
    ..b>Viroids are the simplest noncoding eukaryotic RNA pathogens and genetic units that are capable of autonomous replication ..
  42. Serra P, Gago S, Duran Vila N. A single nucleotide change in Hop stunt viroid modulates citrus cachexia symptoms. Virus Res. 2008;138:130-4 pubmed publisher
    ..These results confirm that the "cachexia expression motif" plays a major role in inciting cachexia symptoms, and that subtle changes within this motif affect symptom severity and may even suppress symptom expression. ..
  43. Verhoeven J, Roenhorst J. High stability of original predominant pospiviroid genotypes upon mechanical inoculation from ornamentals to potato and tomato. Arch Virol. 2010;155:269-74 pubmed publisher
    ..These results confirm the high stability of predominant pospiviroid genotypes. ..
  44. Nohales M, Molina Serrano D, Flores R, Daròs J. Involvement of the chloroplastic isoform of tRNA ligase in the replication of viroids belonging to the family Avsunviroidae. J Virol. 2012;86:8269-76 pubmed publisher
    ..conclusion that the chloroplastic isoform of the plant tRNA ligase is the host enzyme mediating circularization of both (+) and (-) monomeric linear intermediates during replication of the viroids belonging to the family Avsunviroidae.
  45. Shamloul A, Faggioli F, Keith J, Hadidi A. A novel multiplex RT-PCR probe capture hybridization (RT-PCR-ELISA) for simultaneous detection of six viroids in four genera: Apscaviroid, Hostuviroid, Pelamoviroid, and Pospiviroid. J Virol Methods. 2002;105:115-21 pubmed
    A rapid and sensitive assay was developed for the detection and identification of viroids by standard or multiplex reverse transcription-polymerase chain reaction (RT-PCR)-probe capture hybridization (RT-PCR-ELISA)...
  46. Gast F, Kempe D, Sanger H. The dimerization domain of potato spindle tuber viroid, a possible hallmark for infectious RNA. Biochemistry. 1998;37:14098-107 pubmed
    ..Therefore, the dimerization hairpin of viroid RNA represents a unique conformational signal that is homologous to similar regions in the human immunodeficiency virus and other retroviruses...
  47. Gozmanova M, Denti M, Minkov I, Tsagris M, Tabler M. Characterization of the RNA motif responsible for the specific interaction of potato spindle tuber viroid RNA (PSTVd) and the tomato protein Virp1. Nucleic Acids Res. 2003;31:5534-43 pubmed
    b>Viroids are small non-coding parasitic RNAs that are able to infect their host plants systemically. This circular naked RNA makes use of host proteins to accomplish its proliferation...
  48. Palacio Bielsa A, Romero Durbán J, Duran Vila N. Characterization of citrus HSVd isolates. Arch Virol. 2004;149:537-52 pubmed
    ..The stability of the minimum free energy rod-like conformation of the cachexia sequences is lower than the non-cachexia. Information regarding the host effect on the evolution and variability of viroid quasispecies is also provided...
  49. Jiang D, Wu Z, Xie L, Sano T, Li S. Sap-direct RT-PCR for the rapid detection of coleus blumei viroids of the genus Coleviroid from natural host plants. J Virol Methods. 2011;174:123-7 pubmed publisher
    A simple and fast sap-direct RT-PCR (reverse transcription-polymerase chain reaction) for the rapid detection of 3 viroids of the genus Coleviroid is presented...
  50. Tiberini A, Barba M. Optimization and improvement of oligonucleotide microarray-based detection of tomato viruses and pospiviroids. J Virol Methods. 2012;185:43-51 pubmed publisher
    Tomato (Solanum lycopersicum L.) is a vegetable crop which is affected by many viruses and several viroids, causing significant economic loss...
  51. Gomez G, Pallas V. Identification of an in vitro ribonucleoprotein complex between a viroid RNA and a phloem protein from cucumber plants. Mol Plant Microbe Interact. 2001;14:910-3 pubmed
    ..The phloem protein 2 was recovered from this ribonucleoprotein complex and its RNA-binding properties as demonstrated by gel retardation analysis. The involvement of this protein in the movement of RNAs in cucumber is discussed...
  52. Ito T, Ieki H, Ozaki K. Simultaneous detection of six citrus viroids and Apple stem grooving virus from citrus plants by multiplex reverse transcription polymerase chain reaction. J Virol Methods. 2002;106:235-9 pubmed
    We developed a multiplex reverse transcription polymerase chain reaction (RT-PCR) to detect six citrus viroids: Citrus exocortis viroid (CEVd), Citrus bent leaf viroid (CBLVd), Hop stunt viroid (HSVd), Citrus viroid III (CVd-III), Citrus ..
  53. Flores R, Delgado S, Gas M, Carbonell A, Molina D, Gago S, et al. Viroids: the minimal non-coding RNAs with autonomous replication. FEBS Lett. 2004;567:42-8 pubmed
    b>Viroids are small (246-401 nucleotides), non-coding, circular RNAs able to replicate autonomously in certain plants...
  54. Di Serio F, Flores R. Viroids: molecular implements for dissecting RNA trafficking in plants. RNA Biol. 2008;5:128-31 pubmed
    b>Viroids are infectious agents isolated so far only from plants...
  55. Simon A, Gehrke L. RNA conformational changes in the life cycles of RNA viruses, viroids, and virus-associated RNAs. Biochim Biophys Acta. 2009;1789:571-83 pubmed publisher
    ..In this review, we will present some of these molecular rearrangements found in RNA viruses, viroids and virus-associated RNAs, relating how these dynamic regions were discovered, the activities that might be ..
  56. Ding B. Viroids: self-replicating, mobile, and fast-evolving noncoding regulatory RNAs. Wiley Interdiscip Rev RNA. 2010;1:362-75 pubmed publisher
    b>Viroids are small, circular, and noncoding RNAs that infect plants. They replicate in the nucleus or chloroplast and then traffic from cell to cell and from organ to organ to establish systemic infection...
  57. Navarro B, Gisel A, Rodio M, Delgado S, Flores R, Di Serio F. Small RNAs containing the pathogenic determinant of a chloroplast-replicating viroid guide the degradation of a host mRNA as predicted by RNA silencing. Plant J. 2012;70:991-1003 pubmed publisher
    How viroids, tiny non-protein-coding RNAs (~250-400 nt), incite disease is unclear...
  58. Owens R, Sano T, Duran Vila N. Plant viroids: isolation, characterization/detection, and analysis. Methods Mol Biol. 2012;894:253-71 pubmed publisher
    ..sequence-independent, PAGE under denaturing conditions continues to play a key role in the identification of new viroids. Starting in the early 1980s, dot blot hybridization began to replace PAGE for routine viroid diagnosis...
  59. Nohales M, Flores R, Daròs J. Viroid RNA redirects host DNA ligase 1 to act as an RNA ligase. Proc Natl Acad Sci U S A. 2012;109:13805-10 pubmed publisher
    b>Viroids are a unique class of noncoding RNAs: composed of only a circular, single-stranded molecule of 246-401 nt, they manage to replicate, move, circumvent host defenses, and frequently induce disease in higher plants...
  60. Sano T, Ishiguro A. Viability and pathogenicity of intersubgroup viroid chimeras suggest possible involvement of the terminal right region in replication. Virology. 1998;240:238-44 pubmed
    ..regulating viroid replication and pathogenicity, we have examined the biological properties of four chimeric viroids containing sequences derived from hop stunt (HSVd) and citrus exocortis (CEVd) viroids...
  61. Sano T, Mimura R, Ohshima K. Phylogenetic analysis of hop and grapevine isolates of hop stunt viroid supports a grapevine origin for hop stunt disease. Virus Genes. 2001;22:53-9 pubmed
    ..This close relationship between HSVd-hop and -grapevine isolates strongly supports the grapevine origin for hop stunt disease...
  62. Fadda Z, Daros J, Fagoaga C, Flores R, Duran Vila N. Eggplant latent viroid, the candidate type species for a new genus within the family Avsunviroidae (hammerhead viroids). J Virol. 2003;77:6528-32 pubmed
    b>Viroids, small circular RNAs that replicate independently and in most cases incite diseases in plants, are classified into the families Pospiviroidae, composed of species with a central conserved region (CCR) and without hammerhead ..
  63. Markarian N, Li H, Ding S, Semancik J. RNA silencing as related to viroid induced symptom expression. Arch Virol. 2004;149:397-406 pubmed
    ..PTGS induced in Gynura aurantiaca infected with two closely-related variants of Citrus exocortis viroid, a member of family Pospiviroidae, was not directly related to viroid titer with initiation of symptoms...
  64. Tabler M, Tsagris M. Viroids: petite RNA pathogens with distinguished talents. Trends Plant Sci. 2004;9:339-48 pubmed
    b>Viroids are small, circular, single-stranded RNA molecules that cause several infectious plant diseases...
  65. Rocheleau L, Pelchat M. The Subviral RNA Database: a toolbox for viroids, the hepatitis delta virus and satellite RNAs research. BMC Microbiol. 2006;6:24 pubmed
    b>Viroids, satellite RNAs, satellites viruses and the human hepatitis delta virus form the 'brotherhood' of the smallest known infectious RNA agents, known as the subviral RNAs...
  66. Martin R, Arenas C, Daròs J, Covarrubias A, Reyes J, Chua N. Characterization of small RNAs derived from Citrus exocortis viroid (CEVd) in infected tomato plants. Virology. 2007;367:135-46 pubmed
  67. Matsushita Y, Penmetcha K. In vitro-transcribed Chrysanthemum stunt viroid RNA is infectious to chrysanthemum and other plants. Phytopathology. 2009;99:58-66 pubmed publisher
    ..Importantly, the CSVd isolated from these hosts is infectious to chrysanthemum plants, and thus potentially contributes to the spreading of the disease to chrysanthemum plants...
  68. Hajizadeh M, Navarro B, Bashir N, Torchetti E, Di Serio F. Development and validation of a multiplex RT-PCR method for the simultaneous detection of five grapevine viroids. J Virol Methods. 2012;179:62-9 pubmed publisher
    ..Australian grapevine viroid (AGVd), Hop stunt viroid (HSVd) and Citrus exocortis viroid (CEVd) are the five viroids known to infect naturally grapevines...
  69. Owens R, Steger G, Hu Y, Fels A, Hammond R, Riesner D. RNA structural features responsible for potato spindle tuber viroid pathogenicity. Virology. 1996;222:144-58 pubmed
    ..Such alterations in RNA structure together with concomitant alterations in RNA-protein interaction(s) may be the primary cause of viroid pathogenicity...
  70. Amari K, Gomez G, Myrta A, Di Terlizzi B, Pallas V. The molecular characterization of 16 new sequence variants of Hop stunt viroid reveals the existence of invariable regions and a conserved hammerhead-like structure on the viroid molecule. J Gen Virol. 2001;82:953-62 pubmed
    ..Interestingly, a hammerhead-like sequence was found within the T(R) domain of HSVd and it was strictly conserved in all the sequence variants. The evolutionary implications of the presence of this motif on the HSVd are discussed...
  71. Itaya A, Matsuda Y, Gonzales R, Nelson R, Ding B. Potato spindle tuber viroid strains of different pathogenicity induces and suppresses expression of common and unique genes in infected tomato. Mol Plant Microbe Interact. 2002;15:990-9 pubmed
    b>Viroids are the smallest plant pathogens. These RNAs do not encode proteins and are not encapsidated, and yet they can replicate autonomously, move systemically, and cause diseases in infected plants...
  72. Hosokawa M, Otake A, Ohishi K, Ueda E, Hayashi T, Yazawa S. Elimination of chrysanthemum stunt viroid from an infected chrysanthemum cultivar by shoot regeneration from a leaf primordium-free shoot apical meristem dome attached to a root tip. Plant Cell Rep. 2004;22:859-63 pubmed
    ..Regeneration of plants from LP-free SAMs of chrysanthemum plants by attaching these SAMs to root tips is an efficient method of generating CSVd-free chrysanthemum plants...
  73. Eiras M, Kitajima E, Flores R, Daros J. Existence in vivo of the loop E motif in potato spindle tuber viroid RNA. Arch Virol. 2007;152:1389-93 pubmed
    ..experiments have previously identified in potato spindle tuber viroid (PSTVd), the type member of the nuclear viroids, an element of local tertiary structure termed loop E...
  74. Tessitori M, Maria G, Capasso C, Catara G, Rizza S, De Luca V, et al. Differential display analysis of gene expression in Etrog citron leaves infected by Citrus viroid III. Biochim Biophys Acta. 2007;1769:228-35 pubmed
    Citrus are natural hosts of several viroids, which are plant pathogens composed exclusively of a non-protein-coding, small single-stranded circular RNA that is able to replicate autonomously in susceptible hosts...
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    ..The method of return-polyacrylamide gel electrophoresis (R-PAGE) was used to determine the general presence of viroids in the test samples...
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    ..Using the microtissue direct RT-PCR method, both viroids could be detected from the high- and low-viroid-concentration plants...
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    ..The process by which viroid-specific small RNAs are generated appears to be more complicated than previously believed, possibly involving multiple DICER-LIKE activities, viroid RNA substrates and subcellular compartments...
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    ..Genetic diversity and phylogenetic analysis of four predominant sequence variants from this study, plus four others from Australia and Tunisia, revealed obvious regional disparity and variety-specificity in AGVd...
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    b>Viroids and viroid-like satellite RNAs from plants, and the human hepatitis delta virus (HDV) RNA share some properties that include small size, circularity and replication through a rolling-circle mechanism...
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    There is a subviral world, whose most prominent representatives are viroids. Despite being solely composed by a circular, highly structured RNA of ~250 to 400 nucleotides without protein-coding ability (all viruses code for one or more ..
  81. Song A, You Y, Chen F, Li P, Jiang J, Chen S. A multiplex RT-PCR for rapid and simultaneous detection of viruses and viroids in chrysanthemum. Lett Appl Microbiol. 2013;56:8-13 pubmed publisher
    ..The results showed that the multiplex RT-PCR assay proved to be as sensitive as the single one. In conclusion, this technique is potentially useful in routine diagnosis of chrysanthemum viruses and viroids.
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    ..The existence of an integrated program that compiles developmental and defense-related responses is also suggested to explain the characteristic expression pattern detected for these genes as well as for other defense-related genes...
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    ..De novo populations were generated from these infectious variants and like in the original CEVd isolate, both populations presented V1 as the predominant variant but they evolved to a higher nucleotide diversity...
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    b>Viroids are plant subviral pathogens whose genomes are constituted by a single-stranded and covalently closed small RNA molecule that does not encode for any protein...
  85. Carbonell A, de la Peña M, Flores R, Gago S. Effects of the trinucleotide preceding the self-cleavage site on eggplant latent viroid hammerheads: differences in co- and post-transcriptional self-cleavage may explain the lack of trinucleotide AUC in most natural hammerheads. Nucleic Acids Res. 2006;34:5613-22 pubmed
    ..Comparisons with other natural hammerheads showed that the ELVd-(+)-GUC and ELVd-(+)-AUC hammerheads are the catalytically most active in a post-transcriptional context with low magnesium...
  86. Boubourakas I, Fukuta S, Kyriakopoulou P. Sensitive and rapid detection of peach latent mosaic viroid by the reverse transcription loop-mediated isothermal amplification. J Virol Methods. 2009;160:63-8 pubmed publisher
    ..In addition, RT-LAMP was more sensitive than RT-PCR. PLMVd was detected in peach, plum, apricot, pear, wild pear and quince samples...
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    b>Viroids are highly structured plant pathogenic RNAs that do not code for any protein, and thus, their long-distance movement within the plant must be mediated by direct interaction with cellular factors, the nature of which is presently ..
  88. Di Serio F, Daros J, Ragozzino A, Flores R. Close structural relationship between two hammerhead viroid-like RNAs associated with cherry chlorotic rusty spot disease. Arch Virol. 2006;151:1539-49 pubmed
    ..The smaller variants most likely derive from the larger through recombination events. Possible functional relationships between cscRNAs and certain mycoviral-like double-stranded RNAs, also associated with CCRS, are discussed...
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    The mutation rates of viroids, plant pathogens with minimal non-protein-coding RNA genomes, are unknown...
  90. Diener T. Subviral pathogens of plants: viroids and viroidlike satellite RNAs. FASEB J. 1991;5:2808-13 pubmed
    ..These RNAs have been termed viroids. Despite their extremely limited information content, viroids replicate autonomously in susceptible cells--that ..
  91. Wang M, Bian X, Wu L, Liu L, Smith N, Isenegger D, et al. On the role of RNA silencing in the pathogenicity and evolution of viroids and viral satellites. Proc Natl Acad Sci U S A. 2004;101:3275-80 pubmed
    b>Viroids and most viral satellites have small, noncoding, and highly structured RNA genomes. How they cause disease symptoms without encoding proteins and why they have characteristic secondary structures are two longstanding questions...
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    ..Based on these results, on the lack of infectivity of hammerhead-carrying viroids in Arabidopsis, and on extensive sequence comparisons, we propose that the ribozyme sequences did not invade this ..