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Wang H, Chao S, Yan Q, Zhang S, Chen G, Mao C, Hu Y, Yu F, Wang S, Lv L, Yang B, He J, Zhang S, Zhang L, Simmonds P, Feng G. Genetic diversity of RNA viruses infecting invertebrate pests of rice. SCIENCE CHINA. LIFE SCIENCES 2024; 67:175-187. [PMID: 37946067 DOI: 10.1007/s11427-023-2398-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 06/26/2023] [Indexed: 11/12/2023]
Abstract
Invertebrate species are a natural reservoir of viral genetic diversity, and invertebrate pests are widely distributed in crop fields. However, information on viruses infecting invertebrate pests of crops is limited. In this report, we describe the deep metatranscriptomic sequencing of 88 invertebrate samples covering all major invertebrate pests in rice fields. We identified 296 new RNA viruses and 13 known RNA viruses. These viruses clustered within 31 families, with many highly divergent viruses constituting potentially new families and genera. Of the identified viruses, 13 RNA viruses clustered within the Fiersviridae family of bacteriophages, and 48 RNA viruses clustered within families and genera of mycoviruses. We detected known rice viruses in novel invertebrate hosts at high abundances. Furthermore, some novel RNA viruses have genome structures closely matching to known plant viruses and clustered within genera of several plant virus species. Forty-five potential insect pathogenic RNA viruses were detected in invertebrate species. Our analysis revealed that host taxonomy plays a major role and geographical location plays an important role in structuring viral diversity. Cross-species transmission of RNA viruses was detected between invertebrate hosts. Newly identified viral genomes showed extensive variation for invertebrate viral families or genera. Together, the large-scale metatranscriptomic analysis greatly expands our understanding of RNA viruses in rice invertebrate species, the results provide valuable information for developing efficient strategies to manage insect pests and virus-mediated crop diseases.
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Affiliation(s)
- Haoran Wang
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 311400, China
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Shufen Chao
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 311400, China
| | - Qing Yan
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 311400, China
| | - Shu Zhang
- Institute of Plant Protection & Soil Fertilizer, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China
| | - Guoqing Chen
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 311400, China
| | - Chonghui Mao
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 311400, China
| | - Yang Hu
- Institute of Plant Protection, Guizhou Academy of Agricultural Sciences, Guiyang, 550000, China
| | - Fengquan Yu
- Institute of Plant Protection, Liaoning Academy of Agricultural Sciences, Shenyang, 110161, China
| | - Shuo Wang
- Sanya Agricultural Technology Extension and Service Centre, Sanya, 572000, China
| | - Liang Lv
- Institute of Plant Protection & Soil Fertilizer, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China
| | - Baojun Yang
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 311400, China
| | - Jiachun He
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 311400, China
| | - Songbai Zhang
- College of Agriculture, Yangtze University, Jingzhou, 434000, China
| | - Liangsheng Zhang
- Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Genomics and Genetic Engineering Laboratory of Ornamental Plants, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310012, China
| | - Peter Simmonds
- Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford, OX1 3SY, UK
| | - Guozhong Feng
- State Key Laboratory of Rice Biology and Breeding, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 311400, China.
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Sakuta K, Uchida K, Fukuhara T, Komatsu K, Okada R, Moriyama H. Successful full-length genomic cloning and characterization of site-specific nick structures of Phytophthora endornaviruses 2 and 3 in yeast, Saccharomyces cerevisiae. Front Microbiol 2023; 14:1243068. [PMID: 37771702 PMCID: PMC10523305 DOI: 10.3389/fmicb.2023.1243068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/29/2023] [Indexed: 09/30/2023] Open
Abstract
Two endornaviruses, Phytophthora endornavirus 2 (PEV2) and Phytophthora endornavirus 3 (PEV3), have been discovered in pathogens targeting asparagus. In this study, we analyzed the nick structure in the RNA genomes of PEV2 and PEV3 in the host oomycetes. Northern blot hybridization using positive and negative strand-specific RNA probes targeting the 5' and 3' regions of PEV2 and PEV3 RNA genomes revealed approximately 1.0 kilobase (kb) RNA fragments located in the 5' regions of the two genomes. 3' RACE analysis determined that the size of the RNA fragments were 958 nucleotides (nt) for PEV2 and 968 nt for PEV3. We have successfully constructed full-length cDNA clones of the entire RNA genomes of PEV2 and PEV3 using a homologous recombination system in the yeast, Saccharomyces cerevisiae. These full-length cDNA sequences were ligated downstream of a constitutive expression promoter (TDH3) or a galactose-inducing promoter (GAL1) in the shuttle vector to enable the production of the full-length RNA transcripts of PEV2 and PEV3 in yeast cells. Interestingly, a 1.0 kb RNA fragment from the PEV3 positive-strand transcript was also detected with a 5'-region RNA probe, indicating that site-specific cleavage also occurred in yeast cells. Further, when PEV2 or PEV3 mRNA was overexpressed under the GAL1 promoter, yeast cell growth was suppressed. A fusion protein combining EGFP to the N-terminus of the full-length PEV2 ORF or C-terminus of the full-length PEV3 ORF was expressed, and allowed PEV2 and PEV3 ORFs to be successfully visualized in yeast cells. Expression of the fusion protein also revealed presence of heterogeneous bodies in the cells.
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Affiliation(s)
- Kohei Sakuta
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Keiko Uchida
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Toshiyuki Fukuhara
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Ken Komatsu
- Laboratory of Plant Pathology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Ryo Okada
- Horticultural Research Institute, Agricultural Center, Kasama, Ibaraki, Japan
| | - Hiromitsu Moriyama
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
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Bradamante G, Mittelsten Scheid O, Incarbone M. Under siege: virus control in plant meristems and progeny. THE PLANT CELL 2021; 33:2523-2537. [PMID: 34015140 PMCID: PMC8408453 DOI: 10.1093/plcell/koab140] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 05/14/2021] [Indexed: 05/29/2023]
Abstract
In the arms race between plants and viruses, two frontiers have been utilized for decades to combat viral infections in agriculture. First, many pathogenic viruses are excluded from plant meristems, which allows the regeneration of virus-free plant material by tissue culture. Second, vertical transmission of viruses to the host progeny is often inefficient, thereby reducing the danger of viral transmission through seeds. Numerous reports point to the existence of tightly linked meristematic and transgenerational antiviral barriers that remain poorly understood. In this review, we summarize the current understanding of the molecular mechanisms that exclude viruses from plant stem cells and progeny. We also discuss the evidence connecting viral invasion of meristematic cells and the ability of plants to recover from acute infections. Research spanning decades performed on a variety of virus/host combinations has made clear that, beside morphological barriers, RNA interference (RNAi) plays a crucial role in preventing-or allowing-meristem invasion and vertical transmission. How a virus interacts with plant RNAi pathways in the meristem has profound effects on its symptomatology, persistence, replication rates, and, ultimately, entry into the host progeny.
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Affiliation(s)
- Gabriele Bradamante
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
| | - Ortrun Mittelsten Scheid
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
| | - Marco Incarbone
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria
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4
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Uchida K, Sakuta K, Ito A, Takahashi Y, Katayama Y, Omatsu T, Mizutani T, Arie T, Komatsu K, Fukuhara T, Uematsu S, Okada R, Moriyama H. Two Novel Endornaviruses Co-infecting a Phytophthora Pathogen of Asparagus officinalis Modulate the Developmental Stages and Fungicide Sensitivities of the Host Oomycete. Front Microbiol 2021; 12:633502. [PMID: 33633714 PMCID: PMC7902037 DOI: 10.3389/fmicb.2021.633502] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 01/14/2021] [Indexed: 01/06/2023] Open
Abstract
Two novel endornaviruses, Phytophthora endornavirus 2 (PEV2) and Phytophthora endornavirus 3 (PEV3) were found in isolates of a Phytophthora pathogen of asparagus collected in Japan. A molecular phylogenetic analysis indicated that PEV2 and PEV3 belong to the genus Alphaendornavirus. The PEV2 and PEV3 genomes consist of 14,345 and 13,810 bp, and they contain single open reading frames of 4,640 and 4,603 codons, respectively. Their polyproteins contain the conserved domains of an RNA helicase, a UDP-glycosyltransferase, and an RNA-dependent RNA polymerase, which are conserved in other alphaendornaviruses. PEV2 is closely related to Brown algae endornavirus 2, whereas PEV3 is closely related to Phytophthora endornavirus 1 (PEV1), which infects a Phytophthora sp. specific to Douglas fir. PEV2 and PEV3 were detected at high titers in two original Phytophthora sp. isolates, and we found a sub-isolate with low titers of the viruses during subculture. We used the high- and low-titer isolates to evaluate the effects of the viruses on the growth, development, and fungicide sensitivities of the Phytophthora sp. host. The high-titer isolates produced smaller mycelial colonies and much higher numbers of zoosporangia than the low-titer isolate. These results suggest that PEV2 and PEV3 inhibited hyphal growth and stimulated zoosporangium formation. The high-titer isolates were more sensitive than the low-titer isolate to the fungicides benthiavalicarb-isopropyl, famoxadone, and chlorothalonil. In contrast, the high-titer isolates displayed lower sensitivity to the fungicide metalaxyl (an inhibitor of RNA polymerase I) when compared with the low-titer isolate. These results indicate that persistent infection with PEV2 and PEV3 may potentially affect the fungicide sensitivities of the host oomycete.
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Affiliation(s)
- Keiko Uchida
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Kohei Sakuta
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Aori Ito
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Yumi Takahashi
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Yukie Katayama
- Research and Education Center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Tsutomu Omatsu
- Research and Education Center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Tetsuya Mizutani
- Research and Education Center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Tsutomu Arie
- Laboratory of Plant Pathology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Ken Komatsu
- Laboratory of Plant Pathology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Toshiyuki Fukuhara
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Seiji Uematsu
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Ryo Okada
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
| | - Hiromitsu Moriyama
- Laboratory of Molecular and Cellular Biology, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Japan
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5
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Herschlag R, Okada R, Alcalá-Briseño RI, de Souto ER, Valverde RA. Identification of a novel endornavirus in Geranium carolinianum and occurrence within three agroecosystems. Virus Res 2020; 288:198116. [PMID: 32795491 DOI: 10.1016/j.virusres.2020.198116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 10/23/2022]
Abstract
A putative endornavirus was detected in Carolina geranium (Geranium carolinianum) in Louisiana, USA. The virus was provisionally named Geranium carolinianum endornavirus 1 (GcEV1). The viral RNA was sequenced, and it consisted of 14,625 nt containing a single ORF coding a putative polyprotein of 4815 aa with conserved domains for a helicase 1, peptidase C97, glycosyl transferase GTB-type, and RNA-dependent RNA polymerase 2. The 5'end consisted of 130 nt while the 3'end consisted of 54 nt ending in nine cytosine residues. The closest relative to GcEV1 was Phaseolus vulgaris endornavirus 3. In phylogenetic analyses, GcEV1 clustered with members of the genus Alphaendornavirus. GcEV1 was detected in 57 of 60 G. carolinianum plants collected from three distinct agroecosystems. The virus was not detected in eight other species of the genus Geranium. There was no association of a particular phenotypic trait of the host with the presence or absence of the virus. GcEV1 was transmitted at a rate of 100% in seeds of a self-pollinated G. carolinianum plant.
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Affiliation(s)
- Rachel Herschlag
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA, USA
| | - Ryo Okada
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, 183-8509, Japan
| | | | - Eliezer Rodrigues de Souto
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA, USA
| | - Rodrigo A Valverde
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA, USA.
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6
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Fukuhara T, Tabara M, Koiwa H, Takahashi H. Effect of asymptomatic infection with southern tomato virus on tomato plants. Arch Virol 2019; 165:11-20. [PMID: 31620899 DOI: 10.1007/s00705-019-04436-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 09/13/2019] [Indexed: 12/20/2022]
Abstract
Southern tomato virus (STV) is often found infecting healthy tomato plants (Solanum lycopersicum). In this study, we compared STV-free and STV-infected plants of cultivar M82 to determine the effect of STV infection on the host plant. STV-free plants exhibited a short and bushy phenotype, whereas STV-infected plants were taller. STV-infected plants produced more fruit than STV-free plants, and the germination rate of seeds from STV-infected plants was higher than that of seeds from STV-free plants. This phenotypic difference was also observed in progeny plants (siblings) derived from a single STV-infected plant in which the transmission rate of STV to progeny plants via the seeds was approximately 86%. These results suggest that the interaction between STV and host plants is mutualistic. Transcriptome analysis revealed that STV infection affects gene expression in the host plant and results in downregulation of genes involved in ethylene biosynthesis and signaling. STV-infected tomato plants might thus be artificially selected due to their superior traits as a crop.
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Affiliation(s)
- Toshiyuki Fukuhara
- Department of Applied Biological Sciences, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509, Japan. .,Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509, Japan.
| | - Midori Tabara
- Department of Applied Biological Sciences, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509, Japan.,Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509, Japan
| | - Hisashi Koiwa
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo, 183-8509, Japan.,Molecular and Environmental Plant Sciences, Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, TX, 77843, USA
| | - Hideki Takahashi
- Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki-Aza-Aoba, Sendai, 980-0845, Japan
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Gilbert KB, Holcomb EE, Allscheid RL, Carrington JC. Hiding in plain sight: New virus genomes discovered via a systematic analysis of fungal public transcriptomes. PLoS One 2019; 14:e0219207. [PMID: 31339899 PMCID: PMC6655640 DOI: 10.1371/journal.pone.0219207] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 06/18/2019] [Indexed: 11/25/2022] Open
Abstract
The distribution and diversity of RNA viruses in fungi is incompletely understood due to the often cryptic nature of mycoviral infections and the focused study of primarily pathogenic and/or economically important fungi. As most viruses that are known to infect fungi possess either single-stranded or double-stranded RNA genomes, transcriptomic data provides the opportunity to query for viruses in diverse fungal samples without any a priori knowledge of virus infection. Here we describe a systematic survey of all transcriptomic datasets from fungi belonging to the subphylum Pezizomycotina. Using a simple but effective computational pipeline that uses reads discarded during normal RNA-seq analyses, followed by identification of a viral RNA-dependent RNA polymerase (RdRP) motif in de novo assembled contigs, 59 viruses from 44 different fungi were identified. Among the viruses identified, 88% were determined to be new species and 68% are, to our knowledge, the first virus described from the fungal species. Comprehensive analyses of both nucleotide and inferred protein sequences characterize the phylogenetic relationships between these viruses and the known set of mycoviral sequences and support the classification of up to four new families and two new genera. Thus the results provide a deeper understanding of the scope of mycoviral diversity while also increasing the distribution of fungal hosts. Further, this study demonstrates the suitability of analyzing RNA-seq data to facilitate rapid discovery of new viruses.
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Affiliation(s)
- Kerrigan B. Gilbert
- Donald Danforth Plant Science Center, Saint Louis, Missouri, United States of America
| | - Emily E. Holcomb
- Donald Danforth Plant Science Center, Saint Louis, Missouri, United States of America
| | - Robyn L. Allscheid
- Donald Danforth Plant Science Center, Saint Louis, Missouri, United States of America
| | - James C. Carrington
- Donald Danforth Plant Science Center, Saint Louis, Missouri, United States of America
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8
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Endornaviruses: persistent dsRNA viruses with symbiotic properties in diverse eukaryotes. Virus Genes 2019; 55:165-173. [DOI: 10.1007/s11262-019-01635-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 01/07/2019] [Indexed: 10/27/2022]
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9
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Genomic sequence of a novel endornavirus from Phaseolus vulgaris and occurrence in mixed infections with two other endornaviruses. Virus Res 2018; 257:63-67. [DOI: 10.1016/j.virusres.2018.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/07/2018] [Accepted: 09/10/2018] [Indexed: 12/23/2022]
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Sabanadzovic S, Wintermantel WM, Valverde RA, McCreight JD, Aboughanem-Sabanadzovic N. Cucumis melo endornavirus: Genome organization, host range and co-divergence with the host. Virus Res 2016; 214:49-58. [DOI: 10.1016/j.virusres.2016.01.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 12/30/2015] [Accepted: 01/03/2016] [Indexed: 01/30/2023]
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Abstract
Linear double-stranded RNAs (dsRNAs) of about 15 kbp in length are often found from healthy plants, such as bell pepper and rice plants. Nucleotide sequencing and phylogenetic analyses reveal that these dsRNAs are not transcribed from host genomic DNAs, encode a single long open reading frame (ORF) with a viral RNA-dependent RNA polymerase domain, and contain a site-specific nick in the 5' region of their coding strands. Consequently the International Committee on Taxonomy of Viruses has approved that these dsRNAs are viruses forming a distinct taxon, the family Endornaviridae the genus Endornavirus. Endornaviruses have common properties that differ from those of conventional viruses: they have no obvious effect on the phenotype of their host plants, and they are efficiently transmitted to the next generation via both pollen and ova, but their horizontal transfer to other plants has never been proven. Conventional single-stranded RNA viruses, such as cucumber mosaic virus, propagate hugely and systemically in host plants to sometime kill their hosts eventually and transmit horizontally (infect to other plants). In contrast, copy numbers of endornaviruses are low and constant (about 100 copies/cell), and they symbiotically propagate with host plants and transmit vertically. Therefore, endornaviruses are unique plant viruses with symbiotic properties.
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12
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Chen X, Punja ZK. Characterization of a novel dsRNA endornavirus in the plant pathogenic fungus Thielaviopsis basicola. Mycology 2014. [DOI: 10.1080/21501203.2014.884181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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13
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Abstract
Phytophthora sp. is a genus in the oomycetes, which are similar to filamentous fungi in morphology and habitat, but phylogenetically more closely related to brown algae and diatoms and fall in the kingdom Stramenopila. In the past few years, several viruses have been characterized in Phytophthora species, including four viruses from Phytophthora infestans, the late blight pathogen, and an endornavirus from an unnamed Phytophthora species from Douglas fir. Studies on Phytophthora viruses have revealed several interesting systems. Phytophthora infestans RNA virus 1 (PiRV-1) and PiRV-2 are likely the first members of two new virus families; studies on PiRV-3 support the establishment of a new virus genus that is not affiliated with established virus families; PiRV-4 is a member of Narnaviridae, most likely in the genus Narnavirus; and Phytophthora endornavirus 1 (PEV1) was the first nonplant endornavirus at the time of reporting. Viral capsids have not been found in any of the above-mentioned viruses. PiRV-1 demonstrated a unique genome organization that requires further examination, and PiRV-2 may have played a role in late blight resurgence in 1980s-1990s.
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Affiliation(s)
- Guohong Cai
- Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ, USA.
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14
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Okada R, Yong CK, Valverde RA, Sabanadzovic S, Aoki N, Hotate S, Kiyota E, Moriyama H, Fukuhara T. Molecular characterization of two evolutionarily distinct endornaviruses co-infecting common bean (Phaseolus vulgaris). J Gen Virol 2013; 94:220-229. [DOI: 10.1099/vir.0.044487-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Abstract
Two high-molecular-mass dsRNAs of approximately 14 and 15 kbp were isolated from the common bean (Phaseolus vulgaris) cultivar Black Turtle Soup. These dsRNAs did not appear to cause obvious disease symptoms, and were transmitted through seeds at nearly 100 % efficiency. Sequence information indicates that they are the genomes of distinct endornavirus species, for which the names Phaseolus vulgaris endornavirus 1 (PvEV-1) and Phaseolus vulgaris endornavirus 2 (PvEV-2) are proposed. The PvEV-1 genome consists of 13 908 bp and potentially encodes a single polyprotein of 4496 aa, while that of PvEV-2 consists of 14 820 bp and potentially encodes a single ORF of 4851 aa. PvEV-1 is more similar to Oryza sativa endornavirus, while PvEV-2 is more similar to bell pepper endornavirus. Both viruses have a site-specific nick near the 5′ region of the coding strand, which is a common property of the endornaviruses. Their polyproteins contain domains of RNA helicase, UDP-glycosyltransferase and RNA-dependent RNA polymerase, which are conserved in other endornaviruses. However, a viral methyltransferase domain was found in the N-terminal region of PvEV-2, but was absent in PvEV-1. Results of cell-fractionation studies suggested that their subcellular localizations were different. Most endornavirus-infected bean cultivars tested were co-infected with both viruses.
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Affiliation(s)
- Ryo Okada
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Chee Keat Yong
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Rodrigo A. Valverde
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, 70803, USA
| | - Sead Sabanadzovic
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS 39762, USA
| | - Nanako Aoki
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Shunsuke Hotate
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Eri Kiyota
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Hiromitsu Moriyama
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Toshiyuki Fukuhara
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
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15
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Okada R, Kiyota E, Sabanadzovic S, Moriyama H, Fukuhara T, Saha P, Roossinck MJ, Severin A, Valverde RA. Bell pepper endornavirus: molecular and biological properties, and occurrence in the genus Capsicum. J Gen Virol 2011; 92:2664-2673. [DOI: 10.1099/vir.0.034686-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Bell peppers (Capsicum annuum) harbour a large dsRNA virus. The linear genome (14.7 kbp) of two isolates from Japanese and USA bell pepper cultivars were completely sequenced and compared. They shared extensive sequence identity and contained a single, long ORF encoding a 4815 aa protein. This polyprotein contained conserved motifs of putative viral methyltransferase (MTR), helicase 1 (Hel-1), UDP-glycosyltransferase and RNA-dependent RNA polymerase. This unique arrangement of conserved domains has not been reported in any of the known endornaviruses. Hence this virus, for which the name Bell pepper endornavirus (BPEV) is proposed, is a distinct species in the genus Endornavirus (family Endornaviridae). The BPEV-encoded polyprotein contains a cysteine-rich region between the MTR and Hel-1 domains, with conserved CXCC motifs shared among several endornaviruses, suggesting an additional functional domain. In agreement with general endornavirus features, BPEV contains a nick in the positive-strand RNA molecule. The virus was detected in all bell pepper cultivars tested and transmitted through seed but not by graft inoculations. Analysis of dsRNA patterns and RT-PCR using degenerate primers revealed putative variants of BPEV, or closely related species, infecting other C. annuum genotypes and three other Capsicum species (C. baccatum, C. chinense and C. frutescens).
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Affiliation(s)
- Ryo Okada
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Eri Kiyota
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Sead Sabanadzovic
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS 39762, USA
| | - Hiromitsu Moriyama
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Toshiyuki Fukuhara
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Prasenjit Saha
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73402, USA
| | - Marilyn J. Roossinck
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73402, USA
| | - Ake Severin
- Laboratoire de Physiologie Vegetale, Universite de Cocody-Abidjan, UFR Biosciences, 22 BP, 582 Abidjan 22, Côte d'Ivoire
| | - Rodrigo A. Valverde
- Department of Plant Pathology & Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA
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Urayama S, Moriyama H, Aoki N, Nakazawa Y, Okada R, Kiyota E, Miki D, Shimamoto K, Fukuhara T. Knock-down of OsDCL2 in Rice Negatively Affects Maintenance of the Endogenous dsRNA Virus, Oryza sativa Endornavirus. ACTA ACUST UNITED AC 2009; 51:58-67. [DOI: 10.1093/pcp/pcp167] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Valverde RA, Gutierrez DL. Transmission of a dsRNA in bell pepper and evidence that it consists of the genome of an endornavirus. Virus Genes 2007; 35:399-403. [PMID: 17393294 DOI: 10.1007/s11262-007-0092-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2007] [Accepted: 02/26/2007] [Indexed: 11/26/2022]
Abstract
A double-stranded (ds) RNA from bell pepper (BP-dsRNA) cv Yolo Wonder was inherited maternally and paternally after crossing Yolo Wonder with Jalapeño M or Hungarian Wax pepper. Partial sequence information was obtained from two cDNA clones derived from the BP-dsRNA and based on sequence similarity was related to members of the genus Endornavirus. Clones of the BP-dsRNA hybridized with similar dsRNAs from four other pepper cultivars, suggesting that all five dsRNAs tested are related. One of the cDNA clones contained a region that had significant similarity with UDP-glucose:glycosyltransferases from fungi, bacteria, plants, and three endornaviruses. Data presented indicate that the BP-dsRNA is the genome of a distinct species of the genus Endornavirus.
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Affiliation(s)
- Rodrigo A Valverde
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.
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Fukuhara T, Koga R, Aoki N, Yuki C, Yamamoto N, Oyama N, Udagawa T, Horiuchi H, Miyazaki S, Higashi Y, Takeshita M, Ikeda K, Arakawa M, Matsumoto N, Moriyama H. The wide distribution of endornaviruses, large double-stranded RNA replicons with plasmid-like properties. Arch Virol 2005; 151:995-1002. [PMID: 16341944 DOI: 10.1007/s00705-005-0688-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Accepted: 11/02/2005] [Indexed: 10/25/2022]
Abstract
The International Committee on Taxonomy of Viruses (ICTV) recently accepted Endornavirus as a new genus of plant dsRNA virus. We have determined the partial nucleotide sequences of the RNA-dependent RNA polymerase regions from the large dsRNAs (about 14 kbp) isolated from barley (Hordeum vulgare), kidney bean (Phaseolus vulgaris), melon (Cucumis melo), bottle gourd (Lagenaria siceraria), Malabar spinach (Basella alba), seagrass (Zostera marina), and the fungus Helicobasidium mompa. Phylogenetic analyses of these seven dsRNAs indicate that these dsRNAs are new members of the genus Endornavirus that are widely distributed over the plant and fungal kingdoms.
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Affiliation(s)
- T Fukuhara
- Department of Applied Biological Sciences, Tokyo University of Agriculture and Technology, Tokyo, Japan.
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Pina C, Pinto F, Feijó JA, Becker JD. Gene family analysis of the Arabidopsis pollen transcriptome reveals biological implications for cell growth, division control, and gene expression regulation. PLANT PHYSIOLOGY 2005; 138:744-56. [PMID: 15908605 PMCID: PMC1150393 DOI: 10.1104/pp.104.057935] [Citation(s) in RCA: 364] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Upon germination, pollen forms a tube that elongates dramatically through female tissues to reach and fertilize ovules. While essential for the life cycle of higher plants, the genetic basis underlying most of the process is not well understood. We previously used a combination of flow cytometry sorting of viable hydrated pollen grains and GeneChip array analysis of one-third of the Arabidopsis (Arabidopsis thaliana) genome to define a first overview of the pollen transcriptome. We now extend that study to approximately 80% of the genome of Arabidopsis by using Affymetrix Arabidopsis ATH1 arrays and perform comparative analysis of gene family and gene ontology representation in the transcriptome of pollen and vegetative tissues. Pollen grains have a smaller and overall unique transcriptome (6,587 genes expressed) with greater proportions of selectively expressed (11%) and enriched (26%) genes than any vegetative tissue. Relative gene ontology category representations in pollen and vegetative tissues reveal a functional skew of the pollen transcriptome toward signaling, vesicle transport, and the cytoskeleton, suggestive of a commitment to germination and tube growth. Cell cycle analysis reveals an accumulation of G2/M-associated factors that may play a role in the first mitotic division of the zygote. Despite the relative underrepresentation of transcription-associated transcripts, nonclassical MADS box genes emerge as a class with putative unique roles in pollen. The singularity of gene expression control in mature pollen grains is further highlighted by the apparent absence of small RNA pathway components.
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Affiliation(s)
- Cristina Pina
- Centro de Biologia do Desenvolvimento, Instituto Gulbenkian de Ciência, PT-2780-156 Oeiras, Portugal
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Hacker CV, Brasier CM, Buck KW. A double-stranded RNA from a Phytophthora species is related to the plant endornaviruses and contains a putative UDP glycosyltransferase gene. J Gen Virol 2005; 86:1561-1570. [PMID: 15831970 DOI: 10.1099/vir.0.80808-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A new dsRNA was isolated from a Phytophthora isolate from Douglas fir. Sequence analysis showed the dsRNA to consist of 13 883 bp and to contain a single open reading frame with the potential to encode a polyprotein of 4548 aa. This polyprotein contained amino acid sequence motifs characteristic of virus RNA-dependent RNA polymerases (RdRps) in its C-terminal region and motifs characteristic of RNA helicases in its N-terminal region. These sequence motifs were related to corresponding motifs in plant viruses in the genus Endornavirus. In phylogenetic trees constructed from the RdRp and helicase motifs of a range of ssRNA and dsRNA viruses, the Phytophthora RdRp and helicase sequences clustered with those of the plant endornaviruses with good bootstrap support. The properties of the Phytophthora dsRNA are consistent with its being classified as the first non-plant member of the genus Endornavirus, for which we propose the name phytophthora endornavirus 1 (PEV1). A region between the RdRp and helicase domains of the PEV1 protein had significant amino acid sequence similarity to UDP glycosyltransferases (UGTs). Two sequence motifs were identified, one characteristic of all UGTs and the other characteristic of sterol UGTs. The PEV1 UGT would be the first for an RNA virus, although ecdysteroid UGT genes have been found in many baculoviruses. The PEV1 UGT was only distantly related to baculovirus ecdysteroid UGTs, which belong to a family distinct from the sterol UGTs.
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Affiliation(s)
- Caroline V Hacker
- Department of Biological Sciences, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, UK
| | - Clive M Brasier
- Forest Research Agency, Alice Holt Lodge, Farnham, Surrey GU10 4LH, UK
| | - Kenneth W Buck
- Department of Biological Sciences, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, UK
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Horiuchi H, Fukuhara T. Putative Replication Intermediates in Endornavirus, a Novel Genus of Plant dsRNA Viruses. Virus Genes 2004; 29:365-75. [PMID: 15550778 DOI: 10.1007/s11262-004-7441-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Oryza sativa endornavirus (OSV) belongs to a new genus (Endornavirus) and family (Endoviridae) with members containing large double-stranded RNA (dsRNA) replicons with plasmid-like properties. Analysis of products obtained from in vitro reaction of the OSV RNA-dependent RNA polymerase revealed a rapid increase of a population of the non-coding strand RNA molecules with a head-to-tail composition. Northern hybridization of total RNA from OSV-carrier cells with riboprobes specific for the coding strand RNA, revealed two types of RNA molecules (i) with a site specific nick and (ii) full-length unnicked molecules. Quantitative analyses of these RNAs showed about 50-fold higher amounts of full-length unnicked molecules in cultured cells in which the OSV copy number increases compared with those found in the seedling cells. Both the head-to-tail linked non-coding strand and the full-length coding strand molecules were also found in wild rice and broad beans infected with other endornaviruses indicating that the presence of these unique types of RNA molecules should be considered as a characteristic feature of Endoviridae .
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Affiliation(s)
- Hideki Horiuchi
- Department of Applied Biological Sciences, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Tokyo, Japan
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22
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Horiuchi H, Moriyama H, Fukuhara T. Inheritance of Oryza sativa endornavirus in F1 and F2 hybrids between japonica and indica rice. Genes Genet Syst 2003; 78:229-34. [PMID: 12893964 DOI: 10.1266/ggs.78.229] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We have found a 14 kbp double-stranded RNA (dsRNA) in many cultivars of japonica rice (Oryza sativa L.) but not in any cultivars of indica rice. This dsRNA is an RNA replicon with plasmid-like properties and is proposed to be a novel dsRNA virus, Oryza sativa endornavirus (OSV). Reciprocal crosses between the OSV-carrier japonica variety (Nipponbare) and the OSV-free indica variety (IR 26 or Kasalath) were performed to investigate whether OSV can be transmitted to F1 hybrids. When IR 26 and Nipponbare were used, efficient transmission of OSV from ova (93%) and pollen (89%) was observed. When Kasalath and Nipponbare were used, the OSV transmission efficiency to F1 progeny was 68% from ova and 20% from pollen. The transmission of OSV to F2 progeny plants was also complicated, showing non-Mendelian inheritance. These results suggest that the dsRNA replicon (OSV) is unstable in indica rice plants.
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Affiliation(s)
- Hideki Horiuchi
- Department of Applied Biological Sciences, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu, Tokyo 183-8509, Japan
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Bruenn JA. A structural and primary sequence comparison of the viral RNA-dependent RNA polymerases. Nucleic Acids Res 2003; 31:1821-9. [PMID: 12654997 PMCID: PMC152793 DOI: 10.1093/nar/gkg277] [Citation(s) in RCA: 217] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2002] [Revised: 12/02/2002] [Accepted: 01/22/2003] [Indexed: 12/12/2022] Open
Abstract
A systematic bioinformatic approach to identifying the evolutionarily conserved regions of proteins has verified the universality of a newly described conserved motif in RNA-dependent RNA polymerases (motif F). In combination with structural comparisons, this approach has defined two regions that may be involved in unwinding double-stranded RNA (dsRNA) for transcription. One of these is the N-terminal portion of motif F and the second is a large insertion in motif F present in the RNA-dependent RNA polymerases of some dsRNA viruses.
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Affiliation(s)
- Jeremy A Bruenn
- Department of Biological Sciences, State University of New York, Buffalo, NY 14260, USA.
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Horiuchi H, Udagawa T, Koga R, Moriyama H, Fukuhara T. RNA-dependent RNA polymerase activity associated with endogenous double-stranded RNA in rice. PLANT & CELL PHYSIOLOGY 2001; 42:197-203. [PMID: 11230574 DOI: 10.1093/pcp/pce025] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
RNA-dependent RNA polymerase (RdRp) activity was detected in the crude microsomal fraction of rice cultured cells that contain a 14 kbp double-stranded RNA (dsRNA). RdRp activity is maximal in the presence of all four nucleotide triphosphates and Mg2+ ion and is resistant to inhibitors of DNA-dependent RNA polymerases (actinomycin D and alpha-amanitin). RdRp activity increases approximately 2.5-fold in the presence of 0.5% deoxycholate. Treatment of purified microsomal fraction with proteinase K plus deoxycholate suggests that the RdRp enzyme complex with its own 14 kb RNA template is located in vesicles. The RdRp enzyme complex was solubilized with Nonidet P-40 and purified by glycerol gradient centrifugation, then exogenous RNA templates were added. Results indicate that exogenous dsRNA reduces RNA synthesis from the endogenous 14 kb RNA template.
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Affiliation(s)
- H Horiuchi
- Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu, Tokyo, 183-8509 Japan
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Gibbs MJ, Koga R, Moriyama H, Pfeiffer P, Fukuhara T. Phylogenetic analysis of some large double-stranded RNA replicons from plants suggests they evolved from a defective single-stranded RNA virus. J Gen Virol 2000; 81:227-33. [PMID: 10640562 DOI: 10.1099/0022-1317-81-1-227] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sequences were recently obtained from four double-stranded (ds) RNAs from different plant species. These dsRNAs are not associated with particles and as they appeared not to be horizontally transmitted, they were thought to be a kind of RNA plasmid. Here we report that the RNA-dependent RNA polymerase (RdRp) and helicase domains encoded by these dsRNAs are related to those of viruses of the alpha-like virus supergroup. Recent work on the RdRp sequences of alpha-like viruses raised doubts about their relatedness, but our analyses confirm that almost all the viruses previously assigned to the supergroup are related. Alpha-like viruses have single-stranded (ss) RNA genomes and produce particles, and they are much more diverse than the dsRNAs. This difference in diversity suggests the ssRNA alpha-like virus form is older, and we speculate that the transformation to a dsRNA form began when an ancestral ssRNA virus lost its virion protein gene. The phylogeny of the dsRNAs indicates this transformation was not recent and features of the dsRNA genome structure and translation strategy suggest it is now irreversible. Our analyses also show some dsRNAs from distantly related plants are closely related, indicating they have not strictly co-speciated with their hosts. In view of the affinities of the dsRNAs, we believe they should be classified as viruses and we suggest they be recognized as members of a new virus genus (Endornavirus) and family (Endoviridae).
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Affiliation(s)
- M J Gibbs
- Bioinformatics, Research School of Biological Sciences, The Australian National University, GPO Box 475, Canberra 2601, Australia.
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