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Sarropoulou V, Grigoriadou K, Maliogka VI, Sassalou CL, Ziogas V. The Elimination of Viroids through In Vitro Thermotherapy and a Meristem Tip Culture from a New Limonime Hybrid ( Citrus x limon var. limon (L.) Burm. f. x Citrus latifolia var. latifolia). BIOTECH 2024; 13:37. [PMID: 39329829 DOI: 10.3390/biotech13030037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2024] [Revised: 09/19/2024] [Accepted: 09/20/2024] [Indexed: 09/28/2024] Open
Abstract
Viruses and viroids pose a significant challenge in citriculture, and their control is crucial for plant health. This study evaluated the effectiveness of in vitro thermotherapy combined with a meristem tip culture for eliminating citrus exocortis viroid (CEVd) and hop stunt viroid (HSVd) from a new limonime hybrid (Citrus x limon var. limon x Citrus latifolia var. latifolia). The elimination success was confirmed by RT-PCR assays. The in vitro elimination rate for CEVd during the shoot proliferation stage (43%) was higher than for HSVd (21%). Accordingly, in the subsequent rooting stage, the in vitro elimination rate for CEVd (50%) was higher than for HSVd (33%). Successful CEVd and HSVd eradication at a 100% rate was confirmed in the ex vitro acclimatized plants in the greenhouse. The study also established an efficient micropropagation protocol. The optimal treatment for in vitro shoot induction was 0.5-2 mg L-1 benzyladenine (BA) + 0.5 mg L-1 gibberellic acid (GA3) + 0.25 mg L-1 naphthalene acetic acid (NAA), while for shoot elongation, it was 0.5 mg L-1 BA + 0.5 mg L-1 kinetin (KIN) + 0.5 mg L-1 GA3 + 0.25 mg L-1 NAA. Rooting was best promoted by 1 mg L-1 NAA. This study provides valuable insights for the mass production of viroid-free propagation material in this new lemon x lime hybrid, contributing to the conservation of genetic resources in citrus breeding programs through the combined application of in vitro thermotherapy and an in vitro meristem tip culture, a novel and highlighted achievement reported for the first time in this study.
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Affiliation(s)
- Virginia Sarropoulou
- Hellenic Agricultural Organization-DIMITRA (ELGO-DIMITRA), Institute of Plant Breeding and Genetic Resources, Thermi, 57001 Thessaloniki, Greece
| | - Katerina Grigoriadou
- Hellenic Agricultural Organization-DIMITRA (ELGO-DIMITRA), Institute of Plant Breeding and Genetic Resources, Thermi, 57001 Thessaloniki, Greece
| | - Varvara I Maliogka
- Laboratory of Plant Pathology, Faculty of Agriculture, School of Agriculture, Aristotle University of Thessaloniki, Forestry and Natural Environment, 54124 Thessaloniki, Greece
| | - Chrysoula-Lito Sassalou
- Laboratory of Plant Pathology, Faculty of Agriculture, School of Agriculture, Aristotle University of Thessaloniki, Forestry and Natural Environment, 54124 Thessaloniki, Greece
| | - Vasileios Ziogas
- Hellenic Agricultural Organization-DIMITRA (ELGO-DIMITRA), Institute of Olive Tree, Subtropical Crops and Viticulture, 73134 Chania, Greece
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2
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Abualrob A, Alabdallah O, Kubaa RA, Naser SM, Alkowni R. Molecular detection of Citrus exocortis viroid (CEVd), Citrus viroid-III (CVd-III), and Citrus viroid-IV (CVd-IV) in Palestine. Sci Rep 2024; 14:423. [PMID: 38172610 PMCID: PMC10764322 DOI: 10.1038/s41598-023-50271-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 12/18/2023] [Indexed: 01/05/2024] Open
Abstract
Citrus hosts various phytopathogens that have impacted productivity, including viroids. Missing data on the status of viroids in citrus in Palestine were not reported. This study was aimed to detect any of Citrus exocortis viroid (CEVd), Citrus viroid-III (CVd-III), and Citrus viroid-IV (CVd-IV) in the Palestinian National Agricultural Research Center (NARC) germplasm collection Field inspections found symptoms such as leaf epinasty; vein discoloration, and bark cracking on various citrus varieties. RT-PCR revealed a significant prevalence of CVd-IV; CEVd and CVd-III (47%, 31%, and 22%; respectively). CVd-III variants with 91.3% nucleic acid sequence homology have been reported. The sequence of each viroid were deposited in GenBank as (OP925746 for CEVd, OP902248 and OP902249 for CVd-III-PS-1 and -PS-2 isolates, and OP902247 for CVd-IV). This was the first to report three of citrus viroids in Palestine, appealing to apply of phytosanitary measures to disseminate healthy propagating materials free from viroids.
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Affiliation(s)
- Aswar Abualrob
- Biology and Biotechnology Department, An-Najah National University, Nablus, Palestine
| | | | - Raied Abou Kubaa
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA
| | - Sabri M Naser
- Biology and Biotechnology Department, An-Najah National University, Nablus, Palestine
| | - Raed Alkowni
- Biology and Biotechnology Department, An-Najah National University, Nablus, Palestine.
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3
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Incidence and Epidemiology of Citrus Viroids in Greece: Role of Host and Cultivar in Epidemiological Characteristics. Viruses 2023; 15:v15030605. [PMID: 36992314 PMCID: PMC10055999 DOI: 10.3390/v15030605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/01/2023] [Accepted: 02/01/2023] [Indexed: 02/25/2023] Open
Abstract
Viroids represent a threat to the citrus industry and also display an intricate matter for citrus tristeza virus (CTV) control as most of the commercial citrus rootstocks that are resistant/tolerant to CTV appear to be highly susceptible to viroid infection. Therefore, a detailed knowledge of the viroid’s incidence and distribution, along with the assessment of unexplored epidemiological factors leading to their occurrence, are necessary to further improve control measures. Herein, a large-scale epidemiological study of citrus viroids in five districts, 38 locations and 145 fields in Greece is presented, based on the analysis of 3005 samples collected from 29 cultivars of six citrus species. We monitored the occurrence of citrus exocortis (CEVd), hop stunt (HSVd), citrus dwarfing (CDVd), citrus bark cracking (CBCVd), and citrus bent leaf (CBLVd) viroids, and addressed their epidemiological patterns and factors shaping their population structure. Our results show a high frequency and wide distribution of four viroids in all areas and in almost all hosts, whereas CBLVd occurrence was restricted to Crete. Mixed infections were found in all districts in which a wide spread of viroids was observed. We identified a potential pathogens’ different preferences that could be partially explained by the host and cultivar, including the type of infection (single or mixed) and the number of viroids in the mixed infections. Overall, this work provides the first detailed epidemiological study on citrus viroids, enriching our knowledge for the implementation, production, and distribution of certified citrus propagative material, and the development of sustainable control strategies.
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Aviña-Padilla K, Zamora-Macorra EJ, Ochoa-Martínez DL, Alcántar-Aguirre FC, Hernández-Rosales M, Calderón-Zamora L, Hammond RW. Mexico: A Landscape of Viroid Origin and Epidemiological Relevance of Endemic Species. Cells 2022; 11:cells11213487. [PMID: 36359881 PMCID: PMC9653797 DOI: 10.3390/cells11213487] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/24/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022] Open
Abstract
Viroids are single-stranded, circular RNA molecules (234-406 nt) that infect a wide range of crop species and cause economic losses in agriculture worldwide. They are characterized by the existence of a population of sequence variants, attributed to the low fidelity of RNA polymerases involved in their transcription, resulting in high mutation rates. Therefore, these biological entities exist as quasispecies. This feature allows them to replicate within a wide range of host plants, both monocots and dicots. Viroid hosts include economically important crops such as tomato, citrus, and fruit trees such as peach and avocado. Given the high risk of introducing viroids to viroid disease-free countries, these pathogens have been quarantined globally. As discussed herein, Mexico represents a geographical landscape of viroids linked to their origin and comprises considerable biodiversity. The biological features of viroid species endemic to Mexico are highlighted in this communication. In addition, we report the phylogenetic relationships among viroid and viroid strains, their economic impact, geographical distribution, and epidemiological features, including a broad host range and possible long-distance, seed, or insect-mediated transmission. In summary, this review could be helpful for a better understanding of the biology of viroid diseases and future programs on control of movement and spread to avoid economic losses in agricultural industries.
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Affiliation(s)
- Katia Aviña-Padilla
- Centro de Investigacion y de Estudios Avanzados del I.P.N. Unidad Irapuato, Irapuato 36821, Mexico
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Correspondence: or (K.A.-P.); (R.W.H.); Tel.: +1-301-504-5203 (R.W.H.)
| | | | | | | | | | - Loranda Calderón-Zamora
- Facultad de Biologia, Universidad Autonoma de Sinaloa, Calzada de las Americas y calle Universitarios, s/n Ciudad Universitaria, Culiacan 80013, Mexico
| | - Rosemarie W. Hammond
- USDA, Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705, USA
- Correspondence: or (K.A.-P.); (R.W.H.); Tel.: +1-301-504-5203 (R.W.H.)
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Flores R, Navarro B, Serra P, Di Serio F. A scenario for the emergence of protoviroids in the RNA world and for their further evolution into viroids and viroid-like RNAs by modular recombinations and mutations. Virus Evol 2022; 8:veab107. [PMID: 35223083 PMCID: PMC8865084 DOI: 10.1093/ve/veab107] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 12/10/2021] [Accepted: 01/14/2022] [Indexed: 11/14/2022] Open
Abstract
Viroids are tiny, circular, and noncoding RNAs that are able to replicate and systemically infect plants. The smallest known pathogens, viroids have been proposed to represent survivors from the RNA world that likely preceded the cellular world currently dominating life on the earth. Although the small, circular, and compact nature of viroid genomes, some of which are also endowed with catalytic activity mediated by hammerhead ribozymes, support this proposal, the lack of feasible evolutionary routes and the identification of hammerhead ribozymes in a large number of DNA genomes of organisms along the tree of life have led some to question such a proposal. Here, we reassess the origin and subsequent evolution of viroids by complementing phylogenetic reconstructions with molecular data, including the primary and higher-order structure of the genomic RNAs, their replication, and recombination mechanisms and selected biological information. Features of some viroid-like RNAs found in plants, animals, and possibly fungi are also considered. The resulting evolutionary scenario supports the emergence of protoviroids in the RNA world, mainly as replicative modules, followed by a further increase in genome complexity based on module/domain shuffling and combination and mutation. Such a modular evolutionary scenario would have facilitated the inclusion in the protoviroid genomes of complex RNA structures (or coding sequences, as in the case of hepatitis delta virus and delta-like agents), likely needed for their adaptation from the RNA world to a life based on cells, thus generating the ancestors of current infectious viroids and viroid-like RNAs. Other noninfectious viroid-like RNAs, such as retroviroid-like RNA elements and retrozymes, could also be derived from protoviroids if their reverse transcription and integration into viral or eukaryotic DNA, respectively, are considered as a possible key step in their evolution. Comparison of evidence supporting a general and modular evolutionary model for viroids and viroid-like RNAs with that favoring alternative scenarios provides reasonable reasons to keep alive the hypothesis that these small RNA pathogens may be relics of a precellular world.
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Affiliation(s)
- Ricardo Flores
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas–Universidad Politécnica de Valencia, Ingeniero Fausto Elio s/n, Valencia 46022, Spain
| | - Beatriz Navarro
- Istituto per la Protezione Sostenibile delle Piante, Consiglio Nazionale delle Ricerche, Via Amendola 122/D, Bari 70126, Italy
| | - Pedro Serra
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas–Universidad Politécnica de Valencia, Ingeniero Fausto Elio s/n, Valencia 46022, Spain
| | - Francesco Di Serio
- Istituto per la Protezione Sostenibile delle Piante, Consiglio Nazionale delle Ricerche, Via Amendola 122/D, Bari 70126, Italy
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SANO T. Progress in 50 years of viroid research-Molecular structure, pathogenicity, and host adaptation. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2021; 97:371-401. [PMID: 34380915 PMCID: PMC8403530 DOI: 10.2183/pjab.97.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 04/30/2021] [Indexed: 05/27/2023]
Abstract
Viroids are non-encapsidated, single-stranded, circular RNAs consisting of 246-434 nucleotides. Despite their non-protein-encoding RNA nature, viroids replicate autonomously in host cells. To date, more than 25 diseases in more than 15 crops, including vegetables, fruit trees, and flowers, have been reported. Some are pathogenic but others replicate without eliciting disease. Viroids were shown to have one of the fundamental attributes of life to adapt to environments according to Darwinian selection, and they are likely to be living fossils that have survived from the pre-cellular RNA world. In 50 years of research since their discovery, it was revealed that viroids invade host cells, replicate in nuclei or chloroplasts, and undergo nucleotide mutation in the process of adapting to new host environments. It was also demonstrated that structural motifs in viroid RNAs exert different levels of pathogenicity by interacting with various host factors. Despite their small size, the molecular mechanism of viroid pathogenicity turned out to be more complex than first thought.
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Affiliation(s)
- Teruo SANO
- Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori, Japan
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7
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Zhang Z, Xia C, Matsuda T, Taneda A, Murosaki F, Hou W, Owens RA, Li S, Sano T. Effects of Host-Adaptive Mutations on Hop Stunt Viroid Pathogenicity and Small RNA Biogenesis. Int J Mol Sci 2020; 21:ijms21197383. [PMID: 33036282 PMCID: PMC7582576 DOI: 10.3390/ijms21197383] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 09/29/2020] [Accepted: 10/04/2020] [Indexed: 01/02/2023] Open
Abstract
Accidental transmission of hop stunt viroid (HSVd) from grapevine to hop has led to several epidemics of hop stunt disease with convergent evolution of HSVd-g(rape) into HSVd-h(op) containing five mutations. However, the biological function of these five mutations remains unknown. In this study, we compare the biological property of HSVd-g and HSVd-h by bioassay and analyze HSVd-specific small RNA (HSVd-sRNA) using high-throughput sequencing. The bioassay indicated an association of these five mutations with differences in infectivity, replication capacity, and pathogenicity between HSVd-g and HSVd-h, e.g., HSVd-g induced more severe symptoms than HSVd-h in cucumber. Site-directed mutagenesis of HSVd-g showed that the mutation at position 54 increased pathogenicity. HSVd-sRNA analysis of cucumber and hop plants infected with different HSVd variants showed that several sRNA species containing adaptive nucleotides were specifically down-regulated in plants infected with HSVd-h. Several HSVd-sRNAs containing adaptive mutations were predicted to target cucumber genes, but changes in the levels of these genes were not directly correlated with changes in symptom expression. Furthermore, expression levels of two other cucumber genes targeted by HSVd-RNAs, encoding ethylene-responsive transcription factor ERF011, and trihelix transcription factor GTL2, were altered by HSVd infection. The possible relationship between these two genes to HSVd pathogenicity is discussed.
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Affiliation(s)
- Zhixiang Zhang
- State Key Laboratory of Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (Z.Z.); (C.X.); (W.H.)
| | - Changjian Xia
- State Key Laboratory of Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (Z.Z.); (C.X.); (W.H.)
| | - Takahiro Matsuda
- Plant Pathology Laboratory, Faculty of Agriculture and Life Science, Hirosaki University, Bunkyo-cho 3, Hirosaki 036-8561, Japan; (T.M.); (F.M.)
| | - Akito Taneda
- Graduate School of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki 036-8561, Japan;
| | - Fumiko Murosaki
- Plant Pathology Laboratory, Faculty of Agriculture and Life Science, Hirosaki University, Bunkyo-cho 3, Hirosaki 036-8561, Japan; (T.M.); (F.M.)
| | - Wanying Hou
- State Key Laboratory of Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (Z.Z.); (C.X.); (W.H.)
| | - Robert A. Owens
- Molecular Plant Pathology Laboratory, USDA/ARS, Beltsville, MD 20705, USA;
| | - Shifang Li
- State Key Laboratory of Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (Z.Z.); (C.X.); (W.H.)
- Environment and Plant Protection Institute of Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
- Correspondence: (S.L.); (T.S.)
| | - Teruo Sano
- Plant Pathology Laboratory, Faculty of Agriculture and Life Science, Hirosaki University, Bunkyo-cho 3, Hirosaki 036-8561, Japan; (T.M.); (F.M.)
- Correspondence: (S.L.); (T.S.)
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8
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Tangkanchanapas P, Haegeman A, Ruttink T, Höfte M, De Jonghe K. Whole-Genome Deep Sequencing Reveals Host-Driven in-planta Evolution of Columnea Latent Viroid (CLVd) Quasi-Species Populations. Int J Mol Sci 2020; 21:ijms21093262. [PMID: 32380694 PMCID: PMC7246631 DOI: 10.3390/ijms21093262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 04/29/2020] [Accepted: 05/02/2020] [Indexed: 01/06/2023] Open
Abstract
Columnea latent viroid (CLVd) is one of the most serious tomato diseases. In general, viroids have high mutation rates. This generates a population of variants (so-called quasi-species) that co-exist in their host and exhibit a huge level of genetic diversity. To study the population of CLVd in individual host plants, we used amplicon sequencing using specific CLVd primers linked with a sample-specific index sequence to amplify libraries. An infectious clone of a CLVd isolate Chaipayon-1 was inoculated on different solanaceous host plants. Six replicates of the amplicon sequencing results showed very high reproducibility. On average, we obtained 133,449 CLVd reads per PCR-replicate and 79 to 561 viroid sequence variants, depending on the plant species. We identified 19 major variants (>1.0% mean relative abundance) in which a total of 16 single-nucleotide polymorphisms (SNPs) and two single nucleotide insertions were observed. All major variants contained a combination of 4 to 6 SNPs. Secondary structure prediction clustered all major variants into a tomato/bolo maka group with four loops (I, II, IV and V), and a chili pepper group with four loops (I, III, IV and V) at the terminal right domain, compared to the CLVd Chaipayon-1 which consists of five loops (I, II, III, IV and V).
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Affiliation(s)
- Parichate Tangkanchanapas
- Plant Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Burgemeester Van Gansberghelaan 96, 9820 Merelbeke, Belgium; (P.T.); (A.H.); (T.R.)
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium;
| | - Annelies Haegeman
- Plant Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Burgemeester Van Gansberghelaan 96, 9820 Merelbeke, Belgium; (P.T.); (A.H.); (T.R.)
| | - Tom Ruttink
- Plant Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Burgemeester Van Gansberghelaan 96, 9820 Merelbeke, Belgium; (P.T.); (A.H.); (T.R.)
| | - Monica Höfte
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium;
| | - Kris De Jonghe
- Plant Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Burgemeester Van Gansberghelaan 96, 9820 Merelbeke, Belgium; (P.T.); (A.H.); (T.R.)
- Correspondence: ; Tel.: +32-329-2722-448
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Global Transcriptomic Analysis Reveals Insights into the Response of 'Etrog' Citron ( Citrus medica L.) to Citrus Exocortis Viroid Infection. Viruses 2019; 11:v11050453. [PMID: 31109003 PMCID: PMC6563217 DOI: 10.3390/v11050453] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 05/11/2019] [Accepted: 05/15/2019] [Indexed: 12/11/2022] Open
Abstract
Citrus exocortis viroid (CEVd) is the causal agent of citrus exocortis disease. We employed CEVd-infected ‘Etrog’ citron as a system to study the feedback regulation mechanism using transcriptome analysis in this study. Three months after CEVd infection, the transcriptome of fresh leaves was analyzed, and 1530 differentially expressed genes were detected. The replication of CEVd in citron induced upregulation of genes encoding key proteins that were involved in the RNA silencing pathway such as Dicer-like 2, RNA-dependent RNA polymerase 1, argonaute 2, argonaute 7, and silencing defective 3, as well as those genes encoding proteins that are related to basic defense responses. Many genes involved in secondary metabolite biosynthesis and chitinase activity were upregulated, whereas other genes related to cell wall and phytohormone signal transduction were downregulated. Moreover, genes encoding disease resistance proteins, pathogenicity-related proteins, and heat shock cognate 70 kDa proteins were also upregulated in response to CEVd infection. These results suggest that basic defense and RNA silencing mechanisms are activated by CEVd infection, and this information improves our understanding of the pathogenesis of viroids in woody plants.
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Catalán P, Elena SF, Cuesta JA, Manrubia S. Parsimonious Scenario for the Emergence of Viroid-Like Replicons De Novo. Viruses 2019; 11:v11050425. [PMID: 31075860 PMCID: PMC6563258 DOI: 10.3390/v11050425] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/30/2019] [Accepted: 05/02/2019] [Indexed: 01/12/2023] Open
Abstract
Viroids are small, non-coding, circular RNA molecules that infect plants. Different hypotheses for their evolutionary origin have been put forward, such as an early emergence in a precellular RNA World or several de novo independent evolutionary origins in plants. Here, we discuss the plausibility of de novo emergence of viroid-like replicons by giving theoretical support to the likelihood of different steps along a parsimonious evolutionary pathway. While Avsunviroidae-like structures are relatively easy to obtain through evolution of a population of random RNA sequences of fixed length, rod-like structures typical of Pospiviroidae are difficult to fix. Using different quantitative approaches, we evaluated the likelihood that RNA sequences fold into a rod-like structure and bear specific sequence motifs facilitating interactions with other molecules, e.g., RNA polymerases, RNases, and ligases. By means of numerical simulations, we show that circular RNA replicons analogous to Pospiviroidae emerge if evolution is seeded with minimal circular RNAs that grow through the gradual addition of nucleotides. Further, these rod-like replicons often maintain their structure if independent functional modules are acquired that impose selective constraints. The evolutionary scenario we propose here is consistent with the structural and biochemical properties of viroids described to date.
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Affiliation(s)
- Pablo Catalán
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK.
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain.
| | - Santiago F Elena
- Instituto de Biología Integrativa de Sistemas (I2SysBio), CSIC-Universitat de València, Paterna, 46980 València, Spain.
- The Santa Fe Institute, Santa Fe, NM 87501, USA.
| | - José A Cuesta
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain.
- Departamento de Matemáticas, Universidad Carlos III de Madrid, 28911 Leganés, Spain.
- Instituto de Biocomputación y Física de Sistemas Complejos (BiFi), Universidad de Zaragoza, 50018 Zaragoza, Spain.
- Institute of Financial Big Data (IFiBiD), Universidad Carlos III de Madrid⁻Banco de Santander, 28903 Getafe, Spain.
| | - Susanna Manrubia
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain.
- National Biotechnology Centre (CSIC), 28049 Madrid, Spain.
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11
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Chrysanthemum Stunt Viroid Resistance in Chrysanthemum. Viruses 2018; 10:v10120719. [PMID: 30562919 PMCID: PMC6315827 DOI: 10.3390/v10120719] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 12/12/2018] [Accepted: 12/13/2018] [Indexed: 12/17/2022] Open
Abstract
Chrysanthemum stunt viroid (CSVd) is one of the most severe threats in Chrysanthemum morifolium production. Over the last decade, several studies have reported the natural occurrence of CSVd resistance in chrysanthemum germplasms. Such CSVd-resistant germplasms are desirable for the stable production of chrysanthemum plants. Current surveys include finding new resistant chrysanthemum cultivars, breeding, and revealing resistant mechanisms. We review the progress, from discovery to current status, of CSVd-resistance studies, while introducing information on the improvement of associated inoculation and diagnostic techniques.
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12
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Suzuki T, Fujibayashi M, Hataya T, Taneda A, He YH, Tsushima T, Duraisamy GS, Siglová K, Matoušek J, Sano T. Characterization of host-dependent mutations of apple fruit crinkle viroid replicating in newly identified experimental hosts suggests maintenance of stem-loop structures in the left-hand half of the molecule is important for replication. J Gen Virol 2017; 98:506-516. [PMID: 28005527 DOI: 10.1099/jgv.0.000693] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Apple fruit crinkle viroid (AFCVd) is a tentative member of the genus Apscaviroid, family Pospiviroidae. AFCVd has a narrow host range and is known to infect apple, hop and persimmon as natural hosts. In this study, tomato, cucumber and wild hop have been identified as new experimental herbaceous hosts. Foliar symptoms were very mild or virtually undetectable, but fruits of infected tomato were small, cracked and distorted. These symptoms resemble those observed on some AFCVd-sensitive apple cultivars. After transfer to tomato, cucumber and wild hop, sequence changes were detected in a natural AFCVd isolate from hop, and major variants in tomato, cucumber and wild hop differed in 10, 8 or 2 nucleotides, respectively, from the predominant one in the inoculum. The major variants in tomato and cucumber were almost identical, and the one in wild hop was very similar to the one in cultivated hop. Detailed analyses of the host-dependent sequence changes that appear in a naturally occurring AFCVd isolate from hop after transfer to tomato using small RNA deep sequence data and infectivity studies with dimeric RNA transcripts followed by progeny analysis indicate that the major AFCVd variant in tomato emerged by selection of a minor variant present in the inoculum (i.e. hop) followed by one to two host-dependent de novo mutations. Comparison of the secondary structures of major variants in hop, tomato and persimmon after transfer to tomato suggested that maintenance of stem-loop structures in the left-hand half of the molecule is critical for infection.
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Affiliation(s)
- Takahiro Suzuki
- Faculty of Agriculture and Life Science, Hirosaki University, Bunkyo-cho 3, Hirosaki 036-8561, Japan
| | - Misato Fujibayashi
- Faculty of Agriculture and Life Science, Hirosaki University, Bunkyo-cho 3, Hirosaki 036-8561, Japan
| | - Tatsuji Hataya
- Laboratory of Pathogen-Plant Interactions, Research Faculty of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan
| | - Akito Taneda
- Graduate School of Science and Technology, Hirosaki University, Bunkyo-cho 3, Hirosaki 036-8561, Japan
| | - Ying-Hong He
- Faculty of Agriculture and Life Science, Hirosaki University, Bunkyo-cho 3, Hirosaki 036-8561, Japan
| | - Taro Tsushima
- Faculty of Agriculture and Life Science, Hirosaki University, Bunkyo-cho 3, Hirosaki 036-8561, Japan
| | - Ganesh Selvaraj Duraisamy
- Biology Centre ASCR v.v.i, Institute of Plant Molecular Biology, Branišovská 31, České Budějovice 370 05, Czech Republic
| | - Kristyna Siglová
- Biology Centre ASCR v.v.i, Institute of Plant Molecular Biology, Branišovská 31, České Budějovice 370 05, Czech Republic.,University of South Bohemia, Faculty of Science, Branišovská 31, České Budějovice 370 05, Czech Republic
| | - Jaroslav Matoušek
- Biology Centre ASCR v.v.i, Institute of Plant Molecular Biology, Branišovská 31, České Budějovice 370 05, Czech Republic
| | - Teruo Sano
- Faculty of Agriculture and Life Science, Hirosaki University, Bunkyo-cho 3, Hirosaki 036-8561, Japan
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Osman F, Dang T, Bodaghi S, Vidalakis G. One-step multiplex RT-qPCR detects three citrus viroids from different genera in a wide range of hosts. J Virol Methods 2017; 245:40-52. [PMID: 28300606 DOI: 10.1016/j.jviromet.2017.03.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 02/27/2017] [Accepted: 03/10/2017] [Indexed: 01/23/2023]
Abstract
A one-step multiplex reverse transcription real-time quantitative polymerase chain reaction (RT-qPCR) based on species-specific minor groove binding (MGB) probes, was developed for the simultaneous detection, identification, and quantification of three citrus viroids belonging to different genera. Citrus exocortis viroid (Pospiviroid), Hop stunt viroid (Hostuviroid), and Citrus bark cracking viroid (Cocadviroid) cause a variety of maladies in agriculturally significant crops. Therefore, reliable assays for their detection are essential tools for various government and industry organizations implementing disease management programs. Singleplex qPCR primers and MGB probes were designed individually for the detection of the three targeted viroids, and subsequently combined in a one-step multiplex RT-qPCR reaction. A wide host range of woody plants, including citrus, grapevines, apricots, plums and herbaceous plants such as tomato, cucumber, eggplant and chrysanthemum different world regions were used to validate the assay. Single, double and triple viroid infections were identified in the tested samples. The developed multiplex RT-qPCR assay was compared with a previously reported SYBR Green I RT-qPCR for the universal detection of citrus viroids. Both assays accurately identified all citrus viroid infected samples. The multiplex assay complemented the SYBR Green I universal detection assay by differentiating among citrus viroid species in the positive samples. The developed multiplex RT-qPCR assay has the potential to simultaneously detect each targeted viroid and could be used in high throughput screenings for citrus viroids in field surveys, germplasm banks, nurseries and other viroid disease management programs.
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Affiliation(s)
- Fatima Osman
- Department of Plant Pathology, University of California, Davis, CA 95616, USA
| | - Tyler Dang
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA
| | - Sohrab Bodaghi
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA
| | - Georgios Vidalakis
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA.
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14
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Murcia N, Hashemian SMB, Serra P, Pina JA, Duran-Vila N. Citrus Viroids: Symptom Expression and Performance of Washington Navel Sweet Orange Trees Grafted on Carrizo Citrange. PLANT DISEASE 2015; 99:125-136. [PMID: 30699741 DOI: 10.1094/pdis-05-14-0457-re] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Citrus are natural hosts of several viroid species. Citrus exocortis viroid (CEVd) and Hop stunt viroid (HSVd) are the causal agents of two well-known diseases of citrus, exocortis and cachexia. Other viroids have been found to induce specific symptoms and different degrees of stunting in trees grafted on trifoliate orange and trifoliate orange hybrids. A field assay was initiated in 1989 to establish the effect of CEVd, HSVd, Citrus bent leaf viroid (CBLVd), Citrus dwarfing viroid (CDVd), and Citrus bark cracking viroid (CBCVd) on Washington navel sweet orange trees grafted on Carrizo citrange rootstock. Here we report the effect of viroid infection on symptom expression, tree size, fruit production and quality evaluated from 2004 to 2007. Vegetative growth was affected by viroid infection with height and canopy volume being reduced. No bark scaling symptoms were observed in CEVd-infected trees albeit they presented lesions and blisters in the roots. Bark cracking symptoms were consistently observed in CBCVd-infected trees that were smaller with enhanced productivity and fruit size. No major effects were found as a result of infection with CBLVd, HSVd, or CDVd. The quality of the fruits was not affected by viroid infection, except for the low diameter of the fruits harvested from HSVd-infected trees. An interesting effect was identified in terms of tree productivity increase (yield/canopy volume) as a result of infection with CEVd, CDVd, and especially CBCVd.
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Affiliation(s)
- N Murcia
- Departamento de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias, Apartado Oficial, 46113-Moncada, Valencia, Spain
| | - S M Bani Hashemian
- Departamento de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias, Apartado Oficial, 46113-Moncada, Valencia, Spain
| | - P Serra
- Departamento de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias, Apartado Oficial, 46113-Moncada, Valencia, Spain
| | - J A Pina
- Servicio de Semillas y Plantas de Vivero, Apartado Oficial, 46113-Moncada, Valencia, Spain
| | - N Duran-Vila
- Departamento de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias, Apartado Oficial, 46113-Moncada, Valencia, Spain
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15
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What has been happening with viroids? Virus Genes 2014; 49:175-84. [DOI: 10.1007/s11262-014-1110-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 08/18/2014] [Indexed: 12/18/2022]
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16
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Abstract
Because RNA can be a carrier of genetic information and a biocatalyst, there is a consensus that it emerged before DNA and proteins, which eventually assumed these roles and relegated RNA to intermediate functions. If such a scenario--the so-called RNA world--existed, we might hope to find its relics in our present world. The properties of viroids that make them candidates for being survivors of the RNA world include those expected for primitive RNA replicons: (a) small size imposed by error-prone replication, (b) high G + C content to increase replication fidelity, (c) circular structure for assuring complete replication without genomic tags, (d) structural periodicity for modular assembly into enlarged genomes, (e) lack of protein-coding ability consistent with a ribosome-free habitat, and (f) replication mediated in some by ribozymes, the fingerprint of the RNA world. With the advent of DNA and proteins, those protoviroids lost some abilities and became the plant parasites we now know.
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Affiliation(s)
- Ricardo Flores
- Instituto de Biología Molecular y Celular de Plantas (UPV-CSIC), 46022 València, Spain;
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17
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Infectious cDNA clones of four viroids in Coleus blumei and molecular characterization of their progeny. Virus Res 2013; 180:97-101. [PMID: 24291215 DOI: 10.1016/j.virusres.2013.11.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 11/18/2013] [Accepted: 11/18/2013] [Indexed: 11/22/2022]
Abstract
Four viroid species infecting Coleus blumei, named Coleus blumei viroid 1-4 (CbVd-1-CbVd-4), and two tentative new viroid species, named CbVd-5 and CbVd-6, have been characterized, for two of which (CbVd-5 and CbVd-6, first reported in 2009), there is no established bioassay. Here, infectious clones were used as inoculums sources and the biological properties of CbVd-1, -3, -5 and -6 were assessed. When dimeric CbVd (+) RNAs synthesized in vitro were bioassayed, the first detection time for the four CbVds was different, ranging from 45 to 300 days. In addition, we confirmed that CbVd-5 and CbVd-6 can be transmitted via seeds. Molecular characterization of their progeny from slash-inoculated plants one year after inoculation demonstrated that the genetic diversity of CbVd populations may depend on the infected coleus plants and on the viroid genotype.
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18
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Tessitori M, Rizza S, Reina A, Causarano G, Di Serio F. The genetic diversity of Citrus dwarfing viroid populations is mainly dependent on the infected host species. J Gen Virol 2012; 94:687-693. [PMID: 23152366 DOI: 10.1099/vir.0.048025-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
As with viruses, viroids infect their hosts as polymorphic populations of variants. Identifying possible sources of genetic variability is significant in the case of the species Citrus dwarfing viroid (CDVd) which has been proposed as a dwarfing agent for high-density citrus plantings. Here, a natural CDVd isolate (CMC) was used as an inoculum source for long-term (25 years) and short-term (1 year) bioassays in different citrus host species. Characterization of progenies indicated that the genetic stability of CDVd populations was high in certain hosts (trifoliate orange, Troyer citrange, Etrog citron, Navelina sweet orange), which preserve viroid populations similar to the original CMC isolate even after 25 years. By contrast, CDVd variant populations in Interdonato lemon and Volkamer lemon were completely different to those in the inoculated sources, highlighting how influential the host is on the genetic variability of CDVd populations. Implications for risk assessment of CDVd as a dwarfing agent are discussed. The GenBank/EMBL/DDBJ accession numbers for the complete sequences of the Citrus dwarfing viroid variants are JF970266.1 forH2-2, JF970267.1 for H2-7, EU938647.1 for H6-2, EU938651.1 forH6-10, JF970268.1 for H10-7, EU938652.1 for H14-13, EU938653.1for H14-14, JF970269.1 for H14-16, EU938648.1 for H15-9,EU938649.1 for H16-2, JF970265.1 for H16-9, EU938654.1 forH16-13, EU938650.1 for H20-3, JF970270.1 for H20-7, EU938641.1for PR-1, EU938642.1 for PR-3, EU938643.1 for PR-7, EU938644.1for CR-1, EU938639.1 for VR-4, JF12070.1 for VR-15, JF812069.1LS-4, EU938640.1 for LS-10 and JF970264.1 for LS-11.
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Affiliation(s)
- Matilde Tessitori
- Dipartimento di Scienze delle Produzioni Agrarie e Alimentari - Sez. Fitopatologia e Genetica agraria, Università di Catania, 95123 Catania, Italy
| | - Serena Rizza
- Dipartimento di Scienze delle Produzioni Agrarie e Alimentari - Sez. Fitopatologia e Genetica agraria, Università di Catania, 95123 Catania, Italy
| | - Antonella Reina
- Dipartimento di Scienze delle Produzioni Agrarie e Alimentari - Sez. Fitopatologia e Genetica agraria, Università di Catania, 95123 Catania, Italy
| | - Giovanni Causarano
- Dipartimento di Scienze delle Produzioni Agrarie e Alimentari - Sez. Fitopatologia e Genetica agraria, Università di Catania, 95123 Catania, Italy
| | - Francesco Di Serio
- Istituto di Virologia Vegetale, UOS Bari, Consiglio Nazionale delle Ricerche, 70126 Bari, Italy
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19
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Hajeri S, Ramadugu C, Manjunath K, Ng J, Lee R, Vidalakis G. In vivo generated Citrus exocortis viroid progeny variants display a range of phenotypes with altered levels of replication, systemic accumulation and pathogenicity. Virology 2011; 417:400-9. [DOI: 10.1016/j.virol.2011.06.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Revised: 06/11/2011] [Accepted: 06/13/2011] [Indexed: 02/06/2023]
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20
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Elena SF, Gómez G, Daròs JA. Evolutionary constraints to viroid evolution. Viruses 2009; 1:241-54. [PMID: 21994548 PMCID: PMC3185485 DOI: 10.3390/v1020241] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 08/27/2009] [Accepted: 08/27/2009] [Indexed: 11/16/2022] Open
Abstract
We suggest that viroids are trapped into adaptive peaks as the result of adaptive constraints. The first one is imposed by the necessity to fold into packed structures to escape from RNA silencing. This creates antagonistic epistases, which make future adaptive trajectories contingent upon the first mutation and slow down the rate of adaptation. This second constraint can only be surpassed by increasing genetic redundancy or by recombination. Eigen's paradox imposes a limit to the increase in genome complexity in the absence of mechanisms reducing mutation rate. Therefore, recombination appears as the only possible route to evolutionary innovation in viroids.
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Affiliation(s)
- Santiago F. Elena
- Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV), Campus UPV CPI access G, Ingeniero Fausto Elio s/n, 46022 Valencia, Spain; E-Mails: (G.G.); (J.-A.D.)
- The Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
- Author to whom correspondence should be addressed; E-mail: ; Tel.: +34 963 877 895; Fax: +34 963 877 859
| | - Gustavo Gómez
- Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV), Campus UPV CPI access G, Ingeniero Fausto Elio s/n, 46022 Valencia, Spain; E-Mails: (G.G.); (J.-A.D.)
| | - José-Antonio Daròs
- Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV), Campus UPV CPI access G, Ingeniero Fausto Elio s/n, 46022 Valencia, Spain; E-Mails: (G.G.); (J.-A.D.)
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21
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Murcia N, Bernad L, Serra P, Bani Hashemian SM, Duran-Vila N. Molecular and biological characterization of natural variants of Citrus dwarfing viroid. Arch Virol 2009; 154:1329-34. [PMID: 19565323 DOI: 10.1007/s00705-009-0430-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Accepted: 06/10/2009] [Indexed: 11/26/2022]
Abstract
Citrus dwarfing viroid has been proposed as an agent to control tree size in high-density plantations. Thirty-three field isolates have been characterized, and the most frequent sequence/s have been identified. Five distinct variants were selected for biological characterization. Symptom expression analysis demonstrated a good correlation between leaf/stem symptoms and plant growth. The discriminating nucleotide sequence differences included two deletions and an insertion resulting in a reorganization of the base pairing of the terminal left loop, two (G42 --> A and C52 --> U) changes found in one of the variants, and as many as thirteen changes located in the right and left regions flanking the CCR.
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Affiliation(s)
- N Murcia
- Departamento de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias, Centro de Protección Vegetal y Biotecnología, Apartado oficial, 46113 Moncada, Valencia, Spain
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