The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Teruo Sano - One of the best experts on this subject based on the ideXlab platform.
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ICTV Virus Taxonomy Profile: Pospiviroidae.
The Journal of general virology, 2021Co-Authors: Francesco Di Serio, Georgios Vidalakis, Jacobus Th J Verhoeven, Jaroslav Matousek, Teruo Sano, Robert A. Owens, Vicente Pallás, John W. Randles, Ricardo FloresAbstract:Members of the family Pospiviroidae have single-stranded circular RNA genomes that adopt a rod-like or a quasi-rod-like conformation. These genomes contain a central conserved region that is involved in replication in the nucleus through an asymmetric RNA-RNA rolling-circle mechanism. Members of the family Pospiviroidae lack the hammerhead ribozymes that are typical of viroids classified in the family Avsunviroidae. The family Pospiviroidae includes the genera Apscaviroid, Cocadviroid, Coleviroid, Hostuviroid and Pospiviroid, with >25 species. This is a summary of the ICTV Report on the family Pospiviroidae, which is available at ictv.global/report/pospiviroidae.
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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.
The Journal of general virology, 2017Co-Authors: Takahiro Suzuki, Jaroslav Matousek, Misato Fujibayashi, Tatsuji Hataya, Akito Taneda, Taro Tsushima, Ganesh Selvaraj Duraisamy, Kristyna Siglová, Teruo SanoAbstract: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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Other Apscaviroids Infecting Pome Fruit Trees
Viroids and Satellites, 2017Co-Authors: Francesco Di Serio, Ricardo Flores, E.m. Torchetti, Teruo SanoAbstract:Abstract Apple dimple fruit viroid, first reported in Italy, was later identified in Lebanon, China, and Japan, always in apple trees affected by dimple fruit disease. It has been found recently in fig in Italy, but not associated with a specific symptom. Apple fruit crinkle viroid was first reported in apples showing fruit crinkle disease in Japan. Other isolates were reported in hops with symptoms of stunting and leaf curling, and in asymptomatic Japanese persimmons, both cultivated in Japan. Pear blister canker viroid naturally infects pear and quince. It has been reported worldwide, particularly in the Mediterranean basin, although the economic impact is limited because most pear cultivars are tolerant. Apscaviroids infecting pome fruit trees can be detected readily by molecular hybridization and RT-PCR, and controlled by using viroid-free propagation material.
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First Report of Grapevine yellow speckle viroid-1 and Hop stunt viroid Infecting Grapevines (Vitis vinifera) in India.
Plant disease, 2013Co-Authors: A. B. Sahana, C. R. Adkar-purushothama, G. Chennappa, Z. X. Zhang, M. Y. Sreenivasa, Teruo SanoAbstract:During March through July 2012, 10 to 15% of the Vitis vinifera cultivars Thompson Seedless and Anab-e-Shahi exhibited yellow leaf spots and flecks, shortened internodes, and tiny yellow leaves in vineyards of the Bijapur, Doddaballapur, and Kolar districts of Karnataka State, India. These are the major grapevine cultivation regions in India. Samples were collected from four different plants from each district (12 samples in total) and RNA was extracted using 2X CTAB buffer (1). Presence of Grapevine yellow speckle viroid1 (GYSVd-1, genus Apscaviroid) was tested by reverse transcription (RT)-PCR with primer pair PBCVd100C/194H (4) for the amplification of a 220-bp region of the genome. In agarose gel electrophoresis, five samples showed amplicons of the expected size. These amplicons were cloned and sequenced. BLAST analysis confirmed the presence of GYSVd-1. Based on this data, the full-length genome of GYSVd-1 was amplified by RT-PCR using primer pair 341M (5′-CACTCGCGGGGCGCGTTGGA-3′) and 342P (5′-CAATC...
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Characterization of a new viroid strain from hops: evidence for viroid speciation by isolation in different host species
Journal of General Plant Pathology, 2004Co-Authors: Teruo Sano, Hiroshi Yoshida, Masafumi Goshono, Takayuki Monma, Hideto Kawasaki, Keiichiro IshizakiAbstract:A new viroid was detected in hops cultivated in Akita Prefecture, Japan where it is prevalent in many hops fields. In a survey of hop samples collected during the 1986–2002 growing seasons, the new viroid was present in the major Japanese hop-cultivating areas as early as the 1980s. A single-stranded circular RNA of 368–372 nucleotides that assume a highly basepaired, stable, rod-like secondary structure, shares 93%–98% sequence homology with Apple fruit crinkle viroid (AFCVd) isolated from apple and 85%–87% with Australian grapevine viroid (AGVd) isolated from grapevine. Taking into account the present concept of viroid species, we conclude that the viroid is AFCVd. Circumstantial evidence suggests that AFCVd from apples and hops were endemic in Japan only where cultivation of the two host plants overlapped, thereby strongly supporting the possibility that AFCVd (or an ancestral viroid) was transmitted across the species barrier from apples to hops or hops to apples somewhere in the region. Phylogenetic analysis of AFCVd from hops, AFCVd from apples, and AGVd together with the other members of the genus Apscaviroid revealed that the Akita isolates of AFCVd from hops (AFCVd-hop) formed a cluster that is distinct from AFCVd-apple and AGVd. Accumulation of host-specific sequence variation following their isolation in different host species may be leading to the formation of two viroid species from a common ancestor.
Ricardo Flores - One of the best experts on this subject based on the ideXlab platform.
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ICTV Virus Taxonomy Profile: Pospiviroidae.
The Journal of general virology, 2021Co-Authors: Francesco Di Serio, Georgios Vidalakis, Jacobus Th J Verhoeven, Jaroslav Matousek, Teruo Sano, Robert A. Owens, Vicente Pallás, John W. Randles, Ricardo FloresAbstract:Members of the family Pospiviroidae have single-stranded circular RNA genomes that adopt a rod-like or a quasi-rod-like conformation. These genomes contain a central conserved region that is involved in replication in the nucleus through an asymmetric RNA-RNA rolling-circle mechanism. Members of the family Pospiviroidae lack the hammerhead ribozymes that are typical of viroids classified in the family Avsunviroidae. The family Pospiviroidae includes the genera Apscaviroid, Cocadviroid, Coleviroid, Hostuviroid and Pospiviroid, with >25 species. This is a summary of the ICTV Report on the family Pospiviroidae, which is available at ictv.global/report/pospiviroidae.
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Other Apscaviroids Infecting Pome Fruit Trees
Viroids and Satellites, 2017Co-Authors: Francesco Di Serio, Ricardo Flores, E.m. Torchetti, Teruo SanoAbstract:Abstract Apple dimple fruit viroid, first reported in Italy, was later identified in Lebanon, China, and Japan, always in apple trees affected by dimple fruit disease. It has been found recently in fig in Italy, but not associated with a specific symptom. Apple fruit crinkle viroid was first reported in apples showing fruit crinkle disease in Japan. Other isolates were reported in hops with symptoms of stunting and leaf curling, and in asymptomatic Japanese persimmons, both cultivated in Japan. Pear blister canker viroid naturally infects pear and quince. It has been reported worldwide, particularly in the Mediterranean basin, although the economic impact is limited because most pear cultivars are tolerant. Apscaviroids infecting pome fruit trees can be detected readily by molecular hybridization and RT-PCR, and controlled by using viroid-free propagation material.
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citrus viroid v molecular characterization and synergistic interactions with other members of the genus Apscaviroid
Virology, 2008Co-Authors: P Serra, C. J. Barbosa, Ricardo Flores, José-antonio Daròs, N DuranvilaAbstract:Abstract Studies on Atalantia citroides , a citrus relative, revealed the existence of a viroid not described previously. The new viroid has a GC-rich genome of 293–294 nucleotides and contains the central conserved region characteristic of members of the genus Apscaviroid , and the terminal conserved region present in this and other genera of the family Pospiviroidae . The secondary structure of minimum free energy predicted for the new viroid is a rod-like conformation with 68.7% paired nucleotides and showing sequence identities with other viroids always lower than 90%, the conventional limit that separates different species within a given genus. Infectivity assays showed that the new viroid induces mild but characteristic symptoms on the indicator Etrog citron. Co-inoculation of CVd-V with either Citrus bent leaf viroid or Citrus viroid III , two other members of the genus Apscaviroid infecting citrus, disclosed synergistic interactions manifested in enhanced leaf symptoms and very pronounced dwarfing. Viroid titers, however, remained unaltered in co-infected plants. Possible mechanisms underlying the observed synergistic effects are discussed. According to its molecular and biological properties and its unusual ability to replicate in A. citroides , the new viroid, tentatively named Citrus viroid V (CVd-V), should be considered a new species of the genus Apscaviroid.
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Citrus viroid V: occurrence, host range, diagnosis, and identification of new variants.
Phytopathology, 2008Co-Authors: P Serra, Marcelo Eiras, Ricardo Flores, José-antonio Daròs, S. M. Bani-hashemian, N. Murcia, Elliot W. Kitajima, Nuria Duran-vilaAbstract:The recently described Citrus viroid V (CVd-V) has been proposed as a new species of the genus Apscaviroid within the family Pospiviroidae. Analysis of 64 samples from different citrus-growing areas has shown that CVd-V is present in the United States, Spain, Nepal, and the Sultanate of Oman. CVd-V found in six sweet orange sources from the Sultanate of Oman was identical to the reference CVd-V variant, whereas three new variants with sequence identities of 98.6% (CVd-VCA), 97.3% (CVd-VST), and 94.9% (CVd-VNE) were identified in sources from California, Spain, and Nepal, respectively. These results suggest that this viroid has not emerged recently and that it is relatively widespread. Transmission assays to sweet orange, mandarin, and mandarin hybrids, clementine, satsuma, lemon, sour orange, Tahiti lime, Palestine sweet lime, calamondin, bergamot, and kumquat have shown that all these citrus species and citrus relatives are hosts for CVd-V. Several indexing approaches, including slot blot, northern blot hybridization, and reverse transcription-polymerase chain reaction, have been evaluated for detecting CVd-V, either using Etrog citron as an amplification host or directly from commercial species and cultivars.
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Citrus viroid V: occurrence, host range, diagnosis, and identification of new variants.
Phytopathology, 2008Co-Authors: P Serra, Marcelo Eiras, Ricardo Flores, José-antonio Daròs, S. M. Bani-hashemian, N. Murcia, Elliot W. Kitajima, Nuria Duran-vilaAbstract:Serra, P., Eiras, M., Bani-Hashemian, S. M., Murcia, N., Kitajima, E. W., Daros, J. A., Flores, R., and Duran-Vila, N. 2008. Citrus viroid V: Occurrence, host range, diagnosis, and identification of new variants. Phytopathology 98:1199-1204. The recently described Citrus viroid V (CVd-V) has been proposed as a new species of the genus Apscaviroid within the family Pospiviroidae. Analysis of 64 samples from different citrus-growing areas has shown that CVd-V is present in the United States, Spain, Nepal, and the Sultanate of Oman. CVd-V found in six sweet orange sources from the Sultanate of Oman was identical to the reference CVd-V variant, whereas three new variants with sequence identities of 98.6% (CVd-V CA ), 97.3% (CVd-VST), and 94.9% (CVd-VNE) were identified in sources from California, Spain, and Nepal, respectively. These results suggest that this viroid has not emerged recently and that it is relatively widespread. Transmission assays to sweet orange, mandarin, and mandarin hybrids, clementine, satsuma, lemon, sour orange, Tahiti lime, Palestine sweet lime, calamondin, bergamot, and kumquat have shown that all these citrus species and citrus relatives are hosts for CVd-V. Several indexing approaches, including slot blot, northern blot hybridization, and reverse transcription-polymerase chain reaction, have been evaluated for detecting CVd-V, either using Etrog citron as an amplification host or directly from commercial species and cultivars.
Vicente Pallás - One of the best experts on this subject based on the ideXlab platform.
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ICTV Virus Taxonomy Profile: Pospiviroidae.
The Journal of general virology, 2021Co-Authors: Francesco Di Serio, Georgios Vidalakis, Jacobus Th J Verhoeven, Jaroslav Matousek, Teruo Sano, Robert A. Owens, Vicente Pallás, John W. Randles, Ricardo FloresAbstract:Members of the family Pospiviroidae have single-stranded circular RNA genomes that adopt a rod-like or a quasi-rod-like conformation. These genomes contain a central conserved region that is involved in replication in the nucleus through an asymmetric RNA-RNA rolling-circle mechanism. Members of the family Pospiviroidae lack the hammerhead ribozymes that are typical of viroids classified in the family Avsunviroidae. The family Pospiviroidae includes the genera Apscaviroid, Cocadviroid, Coleviroid, Hostuviroid and Pospiviroid, with >25 species. This is a summary of the ICTV Report on the family Pospiviroidae, which is available at ictv.global/report/pospiviroidae.
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Hop stunt viroid: A polyphagous pathogenic RNA that has shed light on viroid-host interactions.
Molecular plant pathology, 2020Co-Authors: Joan Marquez-molins, Gustavo Gómez, Vicente PallásAbstract:Hop stunt viroid (HSVd) is the type species of the genus Hostuviroid (family Pospiviroidae). The other species of this genus is Dahlia latent viroid, which presents an identical central conserved region (CCR) but lacks other structural hallmarks present in Hop stunt viroid. HSVd replication occurs in the nucleus through an asymmetric rolling-circle model as in the other members of the family Pospiviroidae, which also includes the genera Pospiviroid, Cocadviroid, Apscaviroid, and Coleoviroid. Hop stunt viroid consists of a single-stranded, circular RNA of 295-303 nucleotides depending on isolates and sequence variants. The most stable secondary structure is a rod-like or quasi-rod-like conformation with two characteristic domains: a CCR and a terminal conserved hairpin similar to that of cocadviroids. HSVd lacks a terminal conserved region. HSVd infects a very broad range of natural hosts and has been reported to be the causal agent of five different diseases (citrus cachexia, cucumber pale fruit, peach and plum apple apricot distortion, and hop stunt). It is distributed worldwide. HSVd is transmitted mechanically and by seed. © 2020 The Authors. Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd.
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Hop stunt viroid: A polyphagous pathogenic RNA that has shed light on viroid-host interactions.
Molecular plant pathology, 2020Co-Authors: Joan Marquez-molins, Gustavo Gómez, Vicente PallásAbstract:TAXONOMY: Hop stunt viroid (HSVd) is the type species of the genus Hostuviroid (family Pospiviroidae). The other species of this genus is Dahlia latent viroid, which presents an identical central conserved region (CCR) but lacks other structural hallmarks present in Hop stunt viroid. HSVd replication occurs in the nucleus through an asymmetric rolling-circle model as in the other members of the family Pospiviroidae, which also includes the genera Pospiviroid, Cocadviroid, Apscaviroid, and Coleoviroid. PHYSICAL PROPERTIES: Hop stunt viroid consists of a single-stranded, circular RNA of 295-303 nucleotides depending on isolates and sequence variants. The most stable secondary structure is a rod-like or quasi-rod-like conformation with two characteristic domains: a CCR and a terminal conserved hairpin similar to that of cocadviroids. HSVd lacks a terminal conserved region. HOSTS AND SYMPTOMS: HSVd infects a very broad range of natural hosts and has been reported to be the causal agent of five different diseases (citrus cachexia, cucumber pale fruit, peach and plum apple apricot distortion, and hop stunt). It is distributed worldwide. TRANSMISSION: HSVd is transmitted mechanically and by seed.
Hongqing Wang - One of the best experts on this subject based on the ideXlab platform.
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Improved detection of grapevine latent viroid by RT-qPCR, its bioassay analysis, and its rare occurrence worldwide.
Journal of virological methods, 2018Co-Authors: Zhixiang Zhang, Hongqing Wang, Jihong Jiang, Xiyun Cui, Hong Xiao, Nuredin HabiliAbstract:Abstract Three of the five well-known viroids infecting grapevine belong to the genus Apscaviroid. Grapevine latent viroid (GLVd) is a novel grapevine viroid. Although GLVd has the typical sequence motifs of the genus Apscaviroid, it is still an unassigned viroid. In this study, a sensitive, convenient, and rapid one-step RT-qPCR method using hydrolysis probes for the detection of GLVd was developed. Survey and bioassays were also performed for this viroid. Using this method in the survey of GLVd, a low infection rate of 2/226 in a grapevine germplasm resource nursery and a demonstration vineyard in China was determined. Bioassays using agroinfiltration showed that GLVd can infect ‘Kyoho’ grapevine but not any of the tested herbaceous plants. Furthermore, sequence variability of GLVd was analyzed in six GLVd-infected grapevines. Sequencing revealed a predominant variant with only a few nucleotide changes compared with the reference variant of GLVd. Therefore, the developed RT-qPCR method should be helpful for determining GLVd in other vineyards of the world. The low infection rate, host range, and sequence variability of GLVd have important implications to further improve our knowledge on this novel grapevine viroid.
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Identification of a viroid-like RNA in a lychee Transcriptome Shotgun Assembly.
Virus research, 2017Co-Authors: Jihong Jiang, Zhixiang Zhang, Hongqing Wang, Chantal Faure, Armelle Marais, Thierry CandresseAbstract:In the course of a systematic screen of plant transcriptomic data, the sequence of a novel viroid-like RNA was identified in four contigs in a recent Transcriptome Shotgun Assembly (TSA) from lychee in China. Portions of this sequence are closely related to the central conserved region (CCR) and terminal conserved region (TCR) present in members of the genus Apscaviroid, sequences that are important criteria for viroid classification. RT-PCR with two divergent adjacent primers amplified the full 304 nucleotide sequence of this viroid-like RNA which can be folded into the rod-like secondary structure that is a typical feature of viroids in the family Pospiviroidae. Northern-blot hybridization following denaturing PAGE and sequential polyacrylamide gel electrophoresis (sPAGE) revealed the presence of both circular and linear forms of the viroid-like RNA in lychee leaf tissue. Phylogenetic analysis indicates that this RNA groups with known members of the genus Apscaviroid with a maximum pairwise sequence identity of
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Simultaneous Detection of Three Viroid Species Infecting Hops in China by Multiplex RT-PCR
Journal of Phytopathology, 2012Co-Authors: Zhixiang Zhang, Shengxue Liu, Hongqing Wang, Dongmei JiangAbstract:We have developed a multiplex RT-PCR protocol for the simultaneous detection of three viroids in three different genera that infect hops: Hop latent viroid (HLVd; Cocadviroid), Hop stunt viroid (HSVd; Hostuviroid )a ndApple fruit crinkle viroid (AFCVd; Apscaviroid). The method was validated by testing 175 hop samples collected from the Xinjiang autonomous region of China. All samples were found to be positive for HLVd but negative for AFCVd, confirming the widespread or even ubiquitous infection of HLVd and the low incidence of AFCVd in hops in China. In addition, HSVd was detected in 22.86% of the samples tested. This rapid and reliable multiplex RT-PCR assay provides an effective method for detection of three important viroid species in large-scale surveys for disease management in hops.
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Molecular characterization of a member of a new species of grapevine viroid
Archives of virology, 2009Co-Authors: Dongmei Jiang, Rui Guo, Hongqing WangAbstract:Currently, viroids of five species are known to infect grapevine trees: Hop stunt viroid (HSVd-g) [1], Citrus exocortis viroid (CEVd-g) [2], Australian grapevine viroid (AGVd) [3], Grapevine yellow speckle viroid 1 (GYSVd-1) and Grapevine yellow speckle viroid 2 (GYSVd-2) [4–6]. These five grapevine viroid species have been divided into three genera based on sequence homologies of their central conserved regions (CCRs) [7]. GYSVd-1, GYSVd-2, and AGVd are classified in the genus Apscaviroid, whereas HSVd-g [8] and CEVd-g are classified in the genera Hostuviroid and Pospiviroid, respectively [9]. Mixed infections involving these viroids in cultivated grapevines are common, and in general, grapevine viroids produce very few, if any, disease symptoms. In the absence of manifested disease symptoms, these viroids are able to replicate in a host unnoticed. Of the five grapevine viroids identified, GYSVd-1 and GYSVd-2 are associated with disease symptoms such as yellow speckle, which was originally identified under hot greenhouse conditions in Australia [4, 5, 10]. Taylor and Woodham first described yellow speckle (YS) disease in Australia, and it is still the only grapevine disease known to be caused by viroids [10]. GYSVd-1, which is approximately 367 nucleotides (nts) in length, was first isolated from the grapevine cultivar ‘Cabernet Franc’, showing typical symptoms of YS disease. From this cultivar, a single circular RNA was isolated by two-dimensional electrophoresis [4]. GYSVd-2, which is approximately 363 nts in length, was first purified from the grapevine cultivar ‘Kyoto’, which was grafted onto the ‘Dogridge’ rootstock and also exhibited symptoms of YS disease [5]. So far, GYSVd-2 has only been reported in Australia and China [5, 6], and the molecular characterization of GYSVd-2 has been described [11]. Here, we report the characterization of a member of a species of grapevine viroid isolated from China. We call it Chinese grapevine viroid (CGVd) in this report and suggest tentatively naming it Grapevine yellow speckle viroid (GYSVd-3) based on the results of sequence, phylogenetic analysis and molecular characterization.
Nuria Duran-vila - One of the best experts on this subject based on the ideXlab platform.
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First report of citrus viroid V in Moro blood sweet orange in Iran.
Plant disease, 2010Co-Authors: S. M. Bani Hashemian, Nuria Duran-vila, H Taheri, Pedro SerraAbstract:Viroids are nonencapsidated, small, circular, single-stranded RNAs that replicate autonomously when inoculated in their host plants in which they may elicit diseases (sensitive hosts) or replicate as latent infections (tolerant hosts). Citrus viroid V (CVd-V) was initially identified in Spain (1) and later found to be present in the United States, Nepal, and the Sultanate of Oman (2). CVd-V is a member of the Apscaviroid genus within the Pospiviroidae family. Like other members of this genus, CVd-V has a restricted host range but it is able to infect a wide range of citrus and citrus related species (1,2). Within the framework of a comprehensive survey of the sanitary status of the citrus industry in Iran, a sample from a private orchard of symptomless Moro blood sweet orange (Citrus sinensis) trees grafted on Mexican lime (C. aurantifolia) located at Javanan in the southern inland region was found to be infected with CVd-V. Briefly, RNAs of nucleic acid preparations from bark tissues were separated by 5% polyacrylamide gel electrophoresis (PAGE), electrotransferred to positively charged nylon membranes, immobilized by UV cross-linking, and hybridized with a full length CVd-V specific digoxigenin (DIG)-labeled DNA probe (2). A positive identification of CVd-V was made in these extracts. This positive detection of CVd-V was confirmed by reverse transcription-PCR using CVd-V specific primers of opposite polarity (5'-GACGAAGGCCGGTGAGCAGTAAGCC-3') and (5'-GACGACGACAGGTGAGTACTTTC-3') corresponding to CVd-V positions 90 to 114 and 69 to 89, respectively. Analysis of the sequence of the 293-bp amplicon (Genbank Accession No. GQ466068) revealed 99% identity with the reference sequence (Genbank Accession No. NC010165) of CVd-V. The rod-like predicted minimum free energy secondary structure of this new variant has 68.3% paired nucleotides. The changes with respect to the reference CVd-V variant are: (i) a deletion (48→-U) located in a loop of the V domain; (ii) a substitution (155A→C) located in a loop of the TR domain of the viroid secondary structure; and (iii) two compensatory substitutions located in the upper (46A→G) and lower (244U→C) strands of the viroid secondary structure. As shown earlier, the genome of CVd-V allows little variation with a large loop located in the segment I of the secondary structure (2) being the most amenable for mutations/changes. Among the viroids that have been found naturally infecting citrus, the members of the genus Apscaviroid are not associated with specific diseases but they cause a reduction of tree size and fruit harvest (3), an effect that is enhanced when several viroids coinfect the same plant (4). Therefore, the presence of CVd-V should be considered in further indexing tests aimed at the production and distribution of pathogen-free plants in Iran. References: (1) P. Serra et al. Virology 370:102, 2008. (2) P. Serra et al. Phytopathology 98:1199, 2008. (3) C. Verniere et al. Plant Dis. 88:1189, 2004. (4) C. Verniere et al. Phytopathology 96:356, 2006.
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An artificial chimeric derivative of Citrus viroid V involves the terminal left domain in pathogenicity
Molecular plant pathology, 2009Co-Authors: Pedro Serra, Seyed M. Bani Hashemian, Giovanni Pensabene-bellavia, Selma Gago, Nuria Duran-vilaAbstract:The recently described Citrus viroid V (CVd-V) induces, in Etrog citron, mild stunting and very small necrotic lesions and cracks, sometimes filled with gum. As Etrog citron plants co-infected with Citrus dwarfing viroid (CDVd) and CVd-V show synergistic interactions, these host-viroid combinations provide a convenient model to identify the pathogenicity determinant(s). The biological effects of replacing limited portions of the rod-like structure of CVd-V with the corresponding portions of CDVd are reported. Chimeric constructs were synthesized using a novel polymerase chain reaction-based approach, much more flexible than those based on restriction enzymes used in previous studies. Of the seven chimeras (Ch) tested, only one (Ch5) proved to be infectious. Plants infected with Ch5 showed no symptoms and, although this novel chimera was able to replicate to relatively high titres in singly infected plants, it was rapidly displaced by either CVd-V or CDVd in doubly infected plants. The results demonstrate that direct interaction(s) between structural elements in the viroid RNA (in this case, the terminal left domain) and as yet unidentified host factors play an important role in modulating viroid pathogenicity. This is the first pathogenic determinant mapped in species of the genus Apscaviroid.
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Citrus viroid V: occurrence, host range, diagnosis, and identification of new variants.
Phytopathology, 2008Co-Authors: P Serra, Marcelo Eiras, Ricardo Flores, José-antonio Daròs, S. M. Bani-hashemian, N. Murcia, Elliot W. Kitajima, Nuria Duran-vilaAbstract:The recently described Citrus viroid V (CVd-V) has been proposed as a new species of the genus Apscaviroid within the family Pospiviroidae. Analysis of 64 samples from different citrus-growing areas has shown that CVd-V is present in the United States, Spain, Nepal, and the Sultanate of Oman. CVd-V found in six sweet orange sources from the Sultanate of Oman was identical to the reference CVd-V variant, whereas three new variants with sequence identities of 98.6% (CVd-VCA), 97.3% (CVd-VST), and 94.9% (CVd-VNE) were identified in sources from California, Spain, and Nepal, respectively. These results suggest that this viroid has not emerged recently and that it is relatively widespread. Transmission assays to sweet orange, mandarin, and mandarin hybrids, clementine, satsuma, lemon, sour orange, Tahiti lime, Palestine sweet lime, calamondin, bergamot, and kumquat have shown that all these citrus species and citrus relatives are hosts for CVd-V. Several indexing approaches, including slot blot, northern blot hybridization, and reverse transcription-polymerase chain reaction, have been evaluated for detecting CVd-V, either using Etrog citron as an amplification host or directly from commercial species and cultivars.
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Citrus viroid V: occurrence, host range, diagnosis, and identification of new variants.
Phytopathology, 2008Co-Authors: P Serra, Marcelo Eiras, Ricardo Flores, José-antonio Daròs, S. M. Bani-hashemian, N. Murcia, Elliot W. Kitajima, Nuria Duran-vilaAbstract:Serra, P., Eiras, M., Bani-Hashemian, S. M., Murcia, N., Kitajima, E. W., Daros, J. A., Flores, R., and Duran-Vila, N. 2008. Citrus viroid V: Occurrence, host range, diagnosis, and identification of new variants. Phytopathology 98:1199-1204. The recently described Citrus viroid V (CVd-V) has been proposed as a new species of the genus Apscaviroid within the family Pospiviroidae. Analysis of 64 samples from different citrus-growing areas has shown that CVd-V is present in the United States, Spain, Nepal, and the Sultanate of Oman. CVd-V found in six sweet orange sources from the Sultanate of Oman was identical to the reference CVd-V variant, whereas three new variants with sequence identities of 98.6% (CVd-V CA ), 97.3% (CVd-VST), and 94.9% (CVd-VNE) were identified in sources from California, Spain, and Nepal, respectively. These results suggest that this viroid has not emerged recently and that it is relatively widespread. Transmission assays to sweet orange, mandarin, and mandarin hybrids, clementine, satsuma, lemon, sour orange, Tahiti lime, Palestine sweet lime, calamondin, bergamot, and kumquat have shown that all these citrus species and citrus relatives are hosts for CVd-V. Several indexing approaches, including slot blot, northern blot hybridization, and reverse transcription-polymerase chain reaction, have been evaluated for detecting CVd-V, either using Etrog citron as an amplification host or directly from commercial species and cultivars.
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Properties of citrus viroids: Symptom expression and dwarfing
2003Co-Authors: Christian Vernière, Luis Botella, Albert Dubois, Christian Chabrier, Nuria Duran-vilaAbstract:Single viroid sources were selected from the viroid collection maintained at IVIA to evaluate the field performance of infected trees. The assays were conducted in Corsica and Spain using the same viroid sources. Trifoliate orange seedlings infected with CEVd showed severe stunting, yellow blotching of the twigs and the bark scaling symptoms characteristic of the exocortis disease. Bark scaling and stunting symptoms were also observed when trifoliate orange was used as a rootstock. Trifoliate orange seedlings infected with three different sources of CVd-II (IIa, IIb and llc) showed characteristic bark cracks also observed when trifoliate orange was used as a rootstock. Only CVd-IIb and CVd-IIc variants induced cachexia symptoms on tangelo Orlando seedlings and on the scion of clementine trees grafted on trifoliate orange. The two Apscaviroids, CVd-I and specially CVd-III caused a considerable reduction in size of trifoliate orange seedlings also observed when this species was used as a rootstock. No bark symptoms appeared associated with CVd-I and CVd-III infections. CVd-IV infection also caused bark cracking symptoms and size reduction on clementine trees grafted on trifoliate orange but these effects were not apparent on trifoliate orange seedlings. The results of these studies confirm that only CEVd induces the exocortis symptoms as initially described. The bark cracking symptoms and the reduced size resulting from infection with other citrus viroids should not be equated with "exocortis". (Resume d'auteur)