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Abstract
Cacao swollen shoot virus causes cacao swollen shoot disease of Theobroma cacao (cacao) plants. At least six cacao-infecting Badnavirus species-Cacao swollen shoot Togo A virus, Cacao swollen shoot Togo B virus (previously known as Cacao swollen shoot virus), Cacao swollen shoot CE virus, Cacao swollen shoot Ghana M virus, Cacao swollen shoot Ghana N virus, and Cacao swollen shoot Ghana Q virus-are responsible for the swollen shoot disease of cacao in Ghana. Each of these species consists of a multiplicity of strains. The New Juaben strain, the most virulent cacao swollen shoot virus strain in Ghana, belongs to the Cacao swollen shoot Togo B virus species, and is a commonly used strain in laboratory transmission assays. Infection of cacao trees with multiple strains of the virus is common and new evidence suggests that these coinfections may have resulted in the emergence of recombinant strains of the virus. The impact of these emerging recombinant strains on disease severity is uncertain. This review focuses largely on the discovery of cacao swollen shoot virus in Ghana, diversity of the virus strains, molecular characterization, propagation of virus infection in cacao plants, emergence of recombinant virus strains, vector-mediated transmission of the virus, and the management of the cacao swollen shoot disease in Ghana. It also contains sections on the botany and origin of the cacao tree, its introduction to Ghana, the role of cacao swollen shoot disease in facilitating Ghana's independence from Britain, and a brief history of chocolate.
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Affiliation(s)
| | - Owusu Domfeh
- Plant Pathology Division, Cocoa Research Institute of Ghana, New Tafo, Akim, Ghana
| | - George Akumfi Ameyaw
- Plant Pathology Division, Cocoa Research Institute of Ghana, New Tafo, Akim, Ghana
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2
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Status and Epidemiology of Maize Lethal Necrotic Disease in Northern Tanzania. Pathogens 2019; 9:pathogens9010004. [PMID: 31861452 PMCID: PMC7168672 DOI: 10.3390/pathogens9010004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/08/2019] [Accepted: 12/16/2019] [Indexed: 11/16/2022] Open
Abstract
Sustainable control of plant diseases requires a good understanding of the epidemiological aspects such as the biology of the causal pathogens. In the current study, we used RT-PCR and Next Generation Sequencing (NGS) to contribute to the characterization of maize lethal necrotic (MLN) viruses and to identify other possible viruses that could represent a future threat in maize production in Tanzania. RT-PCR screening for Maize Chlorotic Mottle Virus (MCMV) detected the virus in the majority (97%) of the samples (n=223). Analysis of a subset (n=48) of the samples using NGS-Illumina Miseq detected MCMV and Sugarcane Mosaic Virus (SCMV) at a co-infection of 62%. The analysis further detected Maize streak virus with an 8% incidence in samples where MCMV and SCMV were also detected. In addition, signatures of Maize dwarf mosaic virus, Sorghum mosaic virus, Maize yellow dwarf virus-RMV and Barley yellow dwarf virus were detected with low coverage. Phylogenetic analysis of the viral coat protein showed that isolates of MCMV and SCMV were similar to those previously reported in East Africa and Hebei, China. Besides characterization, we used farmers' interviews and direct field observations to give insights into MLN status in different agro-ecological zones (AEZs) in Kilimanjaro, Mayara, and Arusha. Through the survey, we showed that the prevalence of MLN differed across regions (P = 0.0012) and villages (P < 0.0001) but not across AEZs (P > 0.05). The study shows changing MLN dynamicsin Tanzania and emphasizes the need for regional scientists to utilize farmers' awareness in managing the disease.
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3
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Mascia T, Gallitelli D. Synergies and antagonisms in virus interactions. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 252:176-192. [PMID: 27717453 DOI: 10.1016/j.plantsci.2016.07.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 07/22/2016] [Accepted: 07/27/2016] [Indexed: 05/25/2023]
Abstract
Metagenomic surveys and data from next generation sequencing revealed that mixed infections among plant viruses are probably a rule rather than an exception in natural pathosystems. The documented cases may range from synergism to antagonism, which may depend from the spatiotemporal order of arrival of the viruses on the host and upon the host itself. In synergistic interactions, the measurable differences in replication, phenotypic and cytopathological changes, cellular tropism, within host movement, and transmission rate of one of the two viruses or both are increased. Conversely, a decrease in replication, or inhibition of one or more of the above functions by one virus against the other, leads to an antagonistic interaction. Viruses may interact directly and by transcomplementation of defective functions or indirectly, through responses mediated by the host like the defense mechanism based on RNA silencing. Outcomes of these interactions can be applied to the risk assessment of transgenic crops expressing viral proteins, or cross-protected crops for the identification of potential hazards. Prior to experimental evidence, mathematical models may help in forecasting challenges deriving from the great variety of pathways of synergistic and antagonistic interactions. Actually, it seems that such predictions do not receive sufficient credit in the framework of agriculture.
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Affiliation(s)
- Tiziana Mascia
- Dipartimento di Scienze del Suolo della Pianta e degli Alimenti, Università degli Studi di Bari Aldo Moro, Via Amendola 165/A, 70126 Bari, Italy; Istituto del CNR per la Protezione sostenibile delle Piante, Unità Operativa di Supporto di Bari, Via Amendola 165/A, 70126 Bari, Italy
| | - Donato Gallitelli
- Dipartimento di Scienze del Suolo della Pianta e degli Alimenti, Università degli Studi di Bari Aldo Moro, Via Amendola 165/A, 70126 Bari, Italy; Istituto del CNR per la Protezione sostenibile delle Piante, Unità Operativa di Supporto di Bari, Via Amendola 165/A, 70126 Bari, Italy.
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4
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Tripathi D, Raikhy G, Pappu HR. Movement and nucleocapsid proteins coded by two tospovirus species interact through multiple binding regions in mixed infections. Virology 2015; 478:137-47. [PMID: 25666522 DOI: 10.1016/j.virol.2015.01.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 12/07/2014] [Accepted: 01/10/2015] [Indexed: 12/31/2022]
Abstract
Negative-stranded tospoviruses (family: Bunyaviridae) are among the most agronomically important viruses. Some of the tospoviruses are known to exist as mixed infections in the same host plant. Iris yellow spot virus (IYSV) and Tomato spotted wilt virus (TSWV) were used to study virus-virus interaction in dually infected host plants. Viral genes of both viruses were separately cloned into binary pSITE-BiFC vectors. BiFC results showed that the N and NSm proteins of IYSV interact with their counterparts coded by TSWV in dually infected Nicotiana benthamiana plants. BiFC results were further confirmed by pull down and yeast-2-hybrid (Y2H) assays. Interacting regions of the N and NSm proteins were also identified by Y2H system and β-galactosidase activity. Several regions of the N and NSm were found interacting with each other. The regions involved in these interactions are presumed to be critical for the functioning of the tospovirus N and NSm proteins. This is the first report of in vivo protein interactions of distinct tospoviruses in mixed infection.
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Affiliation(s)
- Diwaker Tripathi
- Department of Plant Pathology, Washington State University, P.O. Box 646430, Pullman, WA 99164-6430, USA
| | - Gaurav Raikhy
- Department of Plant Pathology, Washington State University, P.O. Box 646430, Pullman, WA 99164-6430, USA
| | - Hanu R Pappu
- Department of Plant Pathology, Washington State University, P.O. Box 646430, Pullman, WA 99164-6430, USA.
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5
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Abstract
Viruses are common agents of plant infectious diseases. During last decades, worldwide agriculture production has been compromised by a series of epidemics caused by new viruses that spilled over from reservoir species or by new variants of classic viruses that show new pathogenic and epidemiological properties. Virus emergence has been generally associated with ecological change or with intensive agronomical practices. However, the complete picture is much more complex since the viral populations constantly evolve and adapt to their new hosts and vectors. This chapter puts emergence of plant viruses into the framework of evolutionary ecology, genetics, and epidemiology. We will stress that viral emergence begins with the stochastic transmission of preexisting genetic variants from the reservoir to the new host, whose fate depends on their fitness on each hosts, followed by adaptation to new hosts or vectors, and finalizes with an efficient epidemiological spread.
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Affiliation(s)
- Santiago F Elena
- Instituto de Biología Molecular y Celular de Plantas, CSIC-UPV, Campus UPV, València, Spain; The Santa Fe Institute, Santa Fe, New Mexico, USA
| | - Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas, UPM-INIA, and ETSI Agrónomos, UPM, Campus de Montegancedo, Madrid, Spain
| | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas, UPM-INIA, and ETSI Agrónomos, UPM, Campus de Montegancedo, Madrid, Spain.
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6
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Hisa Y, Suzuki H, Atsumi G, Choi SH, Nakahara KS, Uyeda I. P3N-PIPO of Clover yellow vein virus exacerbates symptoms in pea infected with white clover mosaic virus and is implicated in viral synergism. Virology 2014; 449:200-6. [PMID: 24418553 DOI: 10.1016/j.virol.2013.11.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 06/08/2013] [Accepted: 11/07/2013] [Indexed: 11/25/2022]
Abstract
Mixed infection of pea (Pisum sativum) with Clover yellow vein virus (ClYVV) and White clover mosaic virus (WClMV) led to more severe disease symptoms (a phenomenon called viral synergism). Similar to the mixed ClYVV/WClMV infection, a WClMV-based vector encoding P3N-PIPO of ClYVV exacerbated the disease symptoms. Infection with the WClMV vector encoding ClYVV HC-Pro (a suppressor of RNA silencing involved in potyviral synergisms), also resulted in more severe symptoms, although to a lesser extent than infection with the vector encoding P3N-PIPO. Viral genomic RNA accumulated soon after inoculation (at 2 and 4 days) at higher levels in leaves inoculated with WClMV encoding HC-Pro but at lower levels in leaves inoculated with WClMV encoding P3N-PIPO than in peas infected with WClMV encoding GFP. Our results suggest that ClYVV P3N-PIPO is involved in the synergism between ClYVV and WClMV during pea infection through an unknown mechanism different from suppression of RNA silencing.
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Affiliation(s)
- Yusuke Hisa
- Pathogen-Plant Interactions Group, Plant Breeding Science, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
| | - Haruka Suzuki
- Pathogen-Plant Interactions Group, Plant Breeding Science, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
| | - Go Atsumi
- Iwate Biotechnology Research Center, Kitakami 024-0003, Iwate, Japan
| | - Sun Hee Choi
- Pathogen-Plant Interactions Group, Plant Breeding Science, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
| | - Kenji S Nakahara
- Pathogen-Plant Interactions Group, Plant Breeding Science, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
| | - Ichiro Uyeda
- Pathogen-Plant Interactions Group, Plant Breeding Science, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan
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7
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Abstract
More than 70 well-characterized virus species transmitted by a diversity of vectors may infect cucurbit crops worldwide. Twenty of those cause severe epidemics in major production areas, occasionally leading to complete crop failures. Cucurbit viruses' control is based on three major axes: (i) planting healthy seeds or seedlings in a clean environment, (ii) interfering with vectors activity, and (iii) using resistant cultivars. Seed disinfection and seed or seedling quality controls guarantee growers on the sanitary status of their planting material. Removal of virus or vector sources in the crop environment can significantly delay the onset of viral epidemics. Insecticide or oil application may reduce virus spread in some situations. Diverse cultural practices interfere with or prevent vector reaching the crop. Resistance can be obtained by grafting for soil-borne viruses, by cross-protection, or generally by conventional breeding or genetic engineering. The diversity of the actions that may be taken to limit virus spread in cucurbit crops and their limits will be discussed. The ultimate goal is to provide farmers with technical packages that combine these methods within an integrated disease management program and are adapted to different countries and cropping systems.
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Affiliation(s)
- Hervé Lecoq
- INRA, UR407, Station de Pathologie Végétale, Montfavet Cedex, France.
| | - Nikolaos Katis
- Faculty of Agriculture, Forestry and Natural Environment, School of Agriculture, Plant Pathology Lab, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Caracuel Z, Lozano-Durán R, Huguet S, Arroyo-Mateos M, Rodríguez-Negrete EA, Bejarano ER. C2 from Beet curly top virus promotes a cell environment suitable for efficient replication of geminiviruses, providing a novel mechanism of viral synergism. THE NEW PHYTOLOGIST 2012; 194:846-858. [PMID: 22404507 DOI: 10.1111/j.1469-8137.2012.04080.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
• Geminiviruses are plant viruses with circular, single-stranded (ss) DNA genomes that infect a wide range of species and cause important losses in agriculture. Geminiviruses do not encode their own DNA polymerase, and rely on the host cell machinery for their replication. • Here, we identify a positive effect of the curtovirus Beet curly top virus (BCTV) on the begomovirus Tomato yellow leaf curl Sardinia virus (TYLCSV) infection in Nicotiana benthamiana plants. • Our results show that this positive effect is caused by the promotion of TYLCSV replication by BCTV C2. Transcriptomic analyses of plants expressing C2 unveil an up-regulation of cell cycle-related genes induced on cell cycle re-entry; experiments with two mutated versions of C2 indicate that this function resides in the N-terminal part of C2, which is also sufficient to enhance geminiviral replication. Moreover, C2 expression promotes the replication of other geminiviral species, but not of RNA viruses. • We conclude that BCTV C2 has a novel function in the promotion of viral replication, probably by restoring the DNA replication competency of the infected cells and thus creating a favourable cell environment for viral spread. Because C2 seems to have a broad impact on the replication of geminiviruses, this mechanism might have important epidemiological implications.
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Affiliation(s)
- Zaira Caracuel
- Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora', Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain
| | - Rosa Lozano-Durán
- Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora', Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain
| | - Stéphanie Huguet
- Unité de Recherche en Génomique Végétale (URGV), UMR INRA 1165 - Université d'Evry Val d'Essonne - ERL CNRS 8196, 2 rue G. Crémieux, CP 5708, F-91057 Evry Cedex, France
| | - Manuel Arroyo-Mateos
- Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora', Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain
| | - Edgar A Rodríguez-Negrete
- Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora', Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain
| | - Eduardo R Bejarano
- Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora', Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Departamento Biología Celular, Genética y Fisiología, Universidad de Málaga, Campus Teatinos, 29071 Málaga, Spain
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9
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Takeshita M, Koizumi E, Noguchi M, Sueda K, Shimura H, Ishikawa N, Matsuura H, Ohshima K, Natsuaki T, Kuwata S, Furuya N, Tsuchiya K, Masuta C. Infection dynamics in viral spread and interference under the synergism between Cucumber mosaic virus and Turnip mosaic virus. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:18-27. [PMID: 21916556 DOI: 10.1094/mpmi-06-11-0170] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Mixed infection of Cucumber mosaic virus (CMV) and Turnip mosaic virus (TuMV) induced more severe symptoms on Nicotiana benthamiana than single infection. To dissect the relationships between spatial infection patterns and the 2b protein (2b) of CMV in single or mixed infections, the CMV vectors expressing enhanced green fluorescent or Discosoma sp. red fluorescent proteins (EGFP [EG] or DsRed2 [Ds], respectively were constructed from the same wild-type CMV-Y and used for inoculation onto N. benthamiana. CMV2-A1 vector (C2-A1 [A1]) has a functional 2b while CMV-H1 vector (C2-H1 [H1]) is 2b deficient. As we expected from the 2b function as an RNA silencing suppressor (RSS), in a single infection, A1Ds retained a high level of accumulation at initial infection sites and showed extensive fluorescence in upper, noninoculated leaves, whereas H1Ds disappeared rapidly at initial infection sites and could not spread efficiently in upper, noninoculated leaf tissues. In various mixed infections, we found two phenomena providing novel insights into the relationships among RSS, viral synergism, and interference. First, H1Ds could not spread efficiently from vasculature into nonvascular tissues with or without TuMV, suggesting that RNA silencing was not involved in CMV unloading from vasculature. These results indicated that 2b could promote CMV to unload from vasculature into nonvascular tissues, and that this 2b function might be independent of its RSS activity. Second, we detected spatial interference (local interference) between A1Ds and A1EG in mixed infection with TuMV, between A1Ds (or H1Ds) and TuMV, and between H1Ds and H1EG. This observation suggested that local interference between two viruses was established even in the synergism between CMV and TuMV and, again, RNA silencing did not seem to contribute greatly to this phenomenon.
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10
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Sardo L, Wege C, Kober S, Kocher C, Accotto GP, Noris E. RNA viruses and their silencing suppressors boost Abutilon mosaic virus, but not the Old World Tomato yellow leaf curl Sardinia virus. Virus Res 2011; 161:170-80. [PMID: 21843560 DOI: 10.1016/j.virusres.2011.07.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 07/26/2011] [Accepted: 07/27/2011] [Indexed: 11/19/2022]
Abstract
Mixed viral infections can induce different changes in symptom development, genome accumulation and tissue tropism. These issues were investigated for two phloem-limited begomoviruses, Abutilon mosaic virus (AbMV) and Tomato yellow leaf curl Sardinia virus (TYLCSV) in Nicotiana benthamiana plants doubly infected by either the potyvirus Cowpea aphid-borne mosaic virus (CABMV) or the tombusvirus Artichoke mottled crinkle virus (AMCV). Both RNA viruses induced an increase of the amount of AbMV, led to its occasional egress from the phloem and induced symptom aggravation, while the amount and tissue tropism of TYLCSV were almost unaffected. In transgenic plants expressing the silencing suppressors of CABMV (HC-Pro) or AMCV (P19), AbMV was supported to a much lesser extent than in the mixed infections, with the effect of CABMV HC-Pro being superior to that of AMCV P19. Neither of the silencing suppressors influenced TYLCSV accumulation. These results demonstrate that begomoviruses differentially respond to the invasion of other viruses and to silencing suppression.
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Affiliation(s)
- Luca Sardo
- Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, I-10135 Torino, Italy
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11
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The community ecology of barley/cereal yellow dwarf viruses in Western US grasslands. Virus Res 2011; 159:95-100. [DOI: 10.1016/j.virusres.2011.05.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 05/13/2011] [Indexed: 11/22/2022]
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12
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Zwart MP, Daròs JA, Elena SF. One is enough: in vivo effective population size is dose-dependent for a plant RNA virus. PLoS Pathog 2011; 7:e1002122. [PMID: 21750676 PMCID: PMC3131263 DOI: 10.1371/journal.ppat.1002122] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 05/02/2011] [Indexed: 11/19/2022] Open
Abstract
Effective population size (N(e)) determines the strength of genetic drift and the frequency of co-infection by multiple genotypes, making it a key factor in viral evolution. Experimental estimates of N(e) for different plant viruses have, however, rendered diverging results. The independent action hypothesis (IAH) states that each virion has a probability of infection, and that virions act independent of one another during the infection process. A corollary of IAH is that N(e) must be dose dependent. A test of IAH for a plant virus has not been reported yet. Here we perform a test of an IAH infection model using a plant RNA virus, Tobacco etch virus (TEV) variants carrying GFP or mCherry fluorescent markers, in Nicotiana tabacum and Capsicum annuum plants. The number of primary infection foci increased linearly with dose, and was similar to a Poisson distribution. At high doses, primary infection foci containing both genotypes were found at a low frequency (<2%). The probability that a genotype that infected the inoculated leaf would systemically infect that plant was near 1, although in a few rare cases genotypes could be trapped in the inoculated leaf by being physically surrounded by the other genotype. The frequency of mixed-genotype infection could be predicted from the mean number of primary infection foci using the independent-action model. Independent action appears to hold for TEV, and N(e) is therefore dose-dependent for this plant RNA virus. The mean number of virions causing systemic infection can be very small, and approaches 1 at low doses. Dose-dependency in TEV suggests that comparison of N(e) estimates for different viruses are not very meaningful unless dose effects are taken into consideration.
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Affiliation(s)
- Mark P Zwart
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-UPV, València, Spain.
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13
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Abstract
Cross-protection is a phenomenon in which infection of a plant with a mild virus or viroid strain protects it from disease resulting from a subsequent encounter with a severe strain of the same virus or viroid. In this chapter, we review the history of cross-protection with regard to the development of ideas concerning its likely mechanisms, including RNA silencing and exclusion, and its influence on the early development of genetically engineered virus resistance. We also examine examples of the practical use of cross-protection in averting crop losses due to viruses, as well as the use of satellite RNAs to ameliorate the impact of virus-induced diseases. We also discuss the potential of cross-protection to contribute in future to the maintenance of crop health in the face of emerging virus diseases and related threats to agricultural production.
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14
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Martín S, Elena SF. Application of game theory to the interaction between plant viruses during mixed infections. J Gen Virol 2009; 90:2815-2820. [PMID: 19587130 DOI: 10.1099/vir.0.012351-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Natural mixed infections of plant viruses are frequent, often leading to unpredictable variations in symptoms, infectivity, accumulation and/or vector transmissibility. Cauliflower mosaic caulimovirus (CaMV) has often been found in mixed infections with turnip mosaic potyvirus (TuMV) in plants of the genus Brassica. This study addressed the effect of mixed infection on infectivity, pathogenicity and accumulation of CaMV and TuMV in Arabidopsis thaliana plants inoculated mechanically with cDNA infectious clones. In singly infected plants, TuMV accumulation was approximately 8-fold higher than that of CaMV. In co-infected plants, there was 77 % more TuMV accumulation compared with single infections, whilst the accumulation of CaMV was 56 % lower. This outcome describes a biological game in which TuMV always plays the winner strategy, leading to the competitive exclusion of CaMV. However, the infectivity of each virus was not affected by the presence of the other, and no symptom synergism was observed.
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Affiliation(s)
- Susana Martín
- Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV), 46022 València, Spain
| | - Santiago F Elena
- The Santa Fe Institute, Santa Fe, NM 87501, USA.,Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV), 46022 València, Spain
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15
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Vasudevan A, Oh TK, Park JS, Lakshmi SV, Choi BK, Kim SH, Lee HJ, Ji J, Kim JH, Ganapathi A, Kim SC, Choi CW. Characterization of resistance mechanism in transgenic Nicotiana benthamiana containing Turnip crinkle virus coat protein. PLANT CELL REPORTS 2008; 27:1731-40. [PMID: 18704429 DOI: 10.1007/s00299-008-0595-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Revised: 06/30/2008] [Accepted: 07/30/2008] [Indexed: 05/26/2023]
Abstract
Two transgenic lines, of Nicotiana benthamiana expressing Turnip crinkle virus (TCV)-coat protein (CP) gene with contrasting phenotype, the highest (#3) and the lowest (#18) CP expressers, were selected and challenged with the homologous TCV. The former, the highest expresser, showed nearly five times more CP expression than the latter. Progenies of #3 and #18 lines showed 30 and 100% infection rates, respectively. The infected progenies of #3 line showed mild and delayed symptom with TCV. This is a coat protein-mediated resistance (CP-MR), and its resistance level is directly proportional to CP transgene expression. However, CP-MR of the transgenic plants was specific only for TCV but not for heterologous viruses. Newly growing leaves of those infected progenies of #3 line did not show any visible symptoms at 4-week post-inoculation (wpi) with TCV, suggesting a reversal from infection. This was confirmed by RT-PCR analysis with the disappearance of the target at 4 wpi. This is a case of RNA-mediated resistance, and a threshold level of transgene expression may be needed to achieve the silent state. To confirm the RNA silencing, we infiltrated Agrobacterium carrying TCV-CP into leaves of progenies of #3 and performed RT-PCR analysis. The results indicate that TCV-CP's suppressor activity against RNA silencing itself can be silenced by the homologous expression of TCV-CP in the transgenic plants. The transgenic plants containing TCV-CP seem to be a model system to study viral protection mediated by a combination of protein and RNA silencing.
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Affiliation(s)
- Ayyappan Vasudevan
- Department of Biology and Medicinal Science, Pai Chai University, Daejeon, South Korea
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16
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Latham JR, Wilson AK. Transcomplementation and synergism in plants: implications for viral transgenes? MOLECULAR PLANT PATHOLOGY 2008; 9:85-103. [PMID: 18705887 PMCID: PMC6640258 DOI: 10.1111/j.1364-3703.2007.00441.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In plants, viral synergisms occur when one virus enhances infection by a distinct or unrelated virus. Such synergisms may be unidirectional or mutualistic but, in either case, synergism implies that protein(s) from one virus can enhance infection by another. A mechanistically related phenomenon is transcomplementation, in which a viral protein, usually expressed from a transgene, enhances or supports the infection of a virus from a distinct species. To gain an insight into the characteristics and limitations of these helper functions of individual viral genes, and to assess their effects on the plant-pathogen relationship, reports of successful synergism and transcomplementation were compiled from the peer-reviewed literature and combined with data from successful viral gene exchange experiments. Results from these experiments were tabulated to highlight the phylogenetic relationship between the helper and dependent viruses and, where possible, to identify the protein responsible for the altered infection process. The analysis of more than 150 publications, each containing one or more reports of successful exchanges, transcomplementation or synergism, revealed the following: (i) diverse viral traits can be enhanced by synergism and transcomplementation; these include the expansion of host range, acquisition of mechanical transmission, enhanced specific infectivity, enhanced cell-to-cell and long-distance movement, elevated or novel vector transmission, elevated viral titre and enhanced seed transmission; (ii) transcomplementation and synergism are mediated by many viral proteins, including inhibitors of gene silencing, replicases, coat proteins and movement proteins; (iii) although more frequent between closely related viruses, transcomplementation and synergism can occur between viruses that are phylogenetically highly divergent. As indicators of the interoperability of viral genes, these results are of general interest, but they can also be applied to the risk assessment of transgenic crops expressing viral proteins. In particular, they can contribute to the identification of potential hazards, and can be used to identify data gaps and limitations in predicting the likelihood of transgene-mediated transcomplementation.
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Wege C, Siegmund D. Synergism of a DNA and an RNA virus: enhanced tissue infiltration of the begomovirus Abutilon mosaic virus (AbMV) mediated by Cucumber mosaic virus (CMV). Virology 2007; 357:10-28. [PMID: 16959287 DOI: 10.1016/j.virol.2006.07.043] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2005] [Revised: 01/19/2006] [Accepted: 07/26/2006] [Indexed: 11/29/2022]
Abstract
Replication of the begomovirus Abutilon mosaic virus (AbMV) is restricted to phloem nuclei, generating moderate levels of virus DNA. Co-infection with Cucumber mosaic virus (CMV) evidently increased AbMV titers in Nicotiana benthamiana, tobacco, and tomato, resulting in synergistic symptom enhancement. In situ hybridization revealed that in double-infected leaves an increased number of nuclei contained elevated amounts of AbMV. Additionally, the begomoviral phloem-limitation was broken. Whereas CMV 3a movement protein-expressing tobacco plants did not exert any similar influence, the presence of CMV 2b silencing suppressor protein lead to enhanced AbMV titers and numbers of infected vascular cells. The findings prove that AbMV can replicate in nonvascular cells and represent the first report on a true synergism of an RNA/ssDNA virus combination in plants, in which CMV 2b protein plays a role. They indicate considerable consequences of mixed infections between begomo- and cucumoviruses on virus epidemiology and agriculture.
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Affiliation(s)
- Christina Wege
- Department of Plant Molecular Biology and Plant Virology, Universität Stuttgart, Institute of Biology, Pfaffenwaldring 57, D-70569 Stuttgart, Germany.
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Fuchs M, Gonsalves D. Safety of virus-resistant transgenic plants two decades after their introduction: lessons from realistic field risk assessment studies. ANNUAL REVIEW OF PHYTOPATHOLOGY 2007; 45:173-202. [PMID: 17408355 DOI: 10.1146/annurev.phyto.45.062806.094434] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Potential safety issues have been raised with the development and release of virus-resistant transgenic plants. This review focuses on safety assessment with a special emphasis on crops that have been commercialized or extensively tested in the field such as squash, papaya, plum, grape, and sugar beet. We discuss topics commonly perceived to be of concern to the environment and to human health--heteroencapsidation, recombination, synergism, gene flow, impact on nontarget organisms, and food safety in terms of allergenicity. The wealth of field observations and experimental data is critically evaluated to draw inferences on the most relevant issues. We also express inside views on the safety and benefits of virus-resistant transgenic plants, and recommend realistic risk assessment approaches to assist their timely deregulation and release.
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Affiliation(s)
- Marc Fuchs
- Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA.
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Niu QW, Lin SS, Reyes JL, Chen KC, Wu HW, Yeh SD, Chua NH. Expression of artificial microRNAs in transgenic Arabidopsis thaliana confers virus resistance. Nat Biotechnol 2006; 24:1420-8. [PMID: 17057702 DOI: 10.1038/nbt1255] [Citation(s) in RCA: 299] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Accepted: 09/25/2006] [Indexed: 12/31/2022]
Abstract
Plant microRNAs (miRNAs) regulate the abundance of target mRNAs by guiding their cleavage at the sequence complementary region. We have modified an Arabidopsis thaliana miR159 precursor to express artificial miRNAs (amiRNAs) targeting viral mRNA sequences encoding two gene silencing suppressors, P69 of turnip yellow mosaic virus (TYMV) and HC-Pro of turnip mosaic virus (TuMV). Production of these amiRNAs requires A. thaliana DICER-like protein 1. Transgenic A. thaliana plants expressing amiR-P69(159) and amiR-HC-Pro(159) are specifically resistant to TYMV and TuMV, respectively. Expression of amiR-TuCP(159) targeting TuMV coat protein sequences also confers specific TuMV resistance. However, transgenic plants that express both amiR-P69(159) and amiR-HC-Pro(159) from a dimeric pre-amiR-P69(159)/amiR-HC-Pro(159) transgene are resistant to both viruses. The virus resistance trait is displayed at the cell level and is hereditable. More important, the resistance trait is maintained at 15 degrees C, a temperature that compromises small interfering RNA-mediated gene silencing. The amiRNA-mediated approach should have broad applicability for engineering multiple virus resistance in crop plants.
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Affiliation(s)
- Qi-Wen Niu
- Laboratory of Plant Molecular Biology, Rockefeller University, 1230 York Avenue, New York, New York 10021, USA
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Affiliation(s)
- M J Jeger
- Division of Biology, Imperial College London, Wye Campus, Wye Ashford TN25 5AH, United Kingdom
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21
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Parasitism Between Co‐Infecting Bacteriophages. ADV ECOL RES 2005. [DOI: 10.1016/s0065-2504(04)37010-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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22
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Pilson D, Prendeville HR. Ecological Effects of Transgenic Crops and the Escape of Transgenes into Wild Populations. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2004. [DOI: 10.1146/annurev.ecolsys.34.011802.132406] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
▪ Abstract Ecological risks associated with the release of transgenic crops include nontarget effects of the crop and the escape of transgenes into wild populations. Nontarget effects can be of two sorts: (a) unintended negative effects on species that do not reduce yield and (b) greater persistence of the crop in feral populations. Conventional agricultural methods, such as herbicide and pesticide application, have large and well-documented nontarget effects. To the extent that transgenes have more specific target effects, transgenic crops may have fewer nontarget effects. The escape of transgenes into wild populations, via hybridization and introgression, could lead to increased weediness or to the invasion of new habitats by the wild population. In addition, native species with which the wild plant interacts (including herbivores, pathogens, and other plant species in the community) could be negatively affected by “transgenic-wild” plants. Conventional crop alleles have facilitated the evolution of increased weediness in several wild populations. Thus, some transgenes that allow plants to tolerate biotic and abiotic stress (e.g., insect resistance, drought tolerance) could have similar effects.
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Affiliation(s)
- Diana Pilson
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588-0118;,
| | - Holly R. Prendeville
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588-0118;,
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23
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Morilla G, Krenz B, Jeske H, Bejarano ER, Wege C. Tête à tête of tomato yellow leaf curl virus and tomato yellow leaf curl sardinia virus in single nuclei. J Virol 2004; 78:10715-23. [PMID: 15367638 PMCID: PMC516410 DOI: 10.1128/jvi.78.19.10715-10723.2004] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2004] [Accepted: 05/12/2004] [Indexed: 11/20/2022] Open
Abstract
Since 1997 two distinct geminivirus species, Tomato yellow leaf curl Sardinia virus (TYLCSV) and Tomato yellow leaf curl virus (TYLCV), have caused a similar yellow leaf curl disease in tomato, coexisted in the fields of southern Spain, and very frequently doubly infected single plants. Tomatoes as well as experimental test plants (e.g., Nicotiana benthamiana) showed enhanced symptoms upon mixed infections under greenhouse conditions. Viral DNA accumulated to a similar extent in singly and doubly infected plants. In situ tissue hybridization showed TYLCSV and TYLCV DNAs to be confined to the phloem in both hosts, irrespective of whether they were inoculated individually or in combination. The number of infected nuclei in singly or doubly infected plants was determined by in situ hybridization of purified nuclei. The percentage of nuclei containing viral DNA (i.e., 1.4% in tomato or 6% in N. benthamiana) was the same in plants infected with either TYLCSV, TYLCV, or both. In situ hybridization of doubly infected plants, with probes that discriminate between both DNAs, revealed that at least one-fifth of infected nuclei harbored DNAs from both virus species. Such a high number of coinfected nuclei may explain why recombination between different geminivirus DNAs occurs frequently. The impact of these findings for epidemiology and for resistance breeding concerning tomato yellow leaf curl diseases is discussed.
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Affiliation(s)
- Gabriel Morilla
- Departmento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, Málaga, Spain
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Abstract
Virus-resistant transgenic plants (VRTPs) hold the promise of enormous benefit for agriculture. However, over the past ten years, questions concerning the potential ecological impact of VRTPs have been raised. In some cases, detailed study of the mode of action of the resistance gene has made it possible to eliminate the source of potential risk, notably the possible effects of heterologous encapsidation on the transmission of viruses by their vectors. In other cases, the means of eliminating likely sources of risk have not yet been developed. When such residual risk still exists, the potential risks associated with the VRTP must be compared with those associated with nontransgenic plants so that risk assessment can fully play its role as part of an overall analysis of the advantages and disadvantages of practicable solutions to the problem solved by the VRTP.
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Affiliation(s)
- Mark Tepfer
- Laboratoire de Biologie Cellulaire, INRA-Versailles, F-78026 Versailles cedex, France.
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Jeske H, Lütgemeier M, Preiss W. DNA forms indicate rolling circle and recombination-dependent replication of Abutilon mosaic virus. EMBO J 2001; 20:6158-67. [PMID: 11689455 PMCID: PMC125697 DOI: 10.1093/emboj/20.21.6158] [Citation(s) in RCA: 190] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Geminiviruses have spread worldwide and have become increasingly important in crop plants during recent decades. Recombination among geminiviruses was one major source of new variants. Geminiviruses replicate via rolling circles, confirmed here by electron microscopic visualization and two-dimensional gel analysis of Abutilon mosaic virus (AbMV) DNA. However, only a minority of DNA intermediates are consistent with this model. The majority are compatible with recombination-dependent replication (RDR). During development of naturally infected leaves, viral intermediates compatible with both models appeared simultaneously, whereas agro-infection of leaf discs with AbMV led to an early appearance of RDR forms but no RCR intermediates. Inactivation of viral genes ac2 and ac3 delayed replication, but produced the same DNA types as after wild-type infection, indicating that these genes were not essential for RDR in leaf discs. In conclusion, host factors alone or in combination with the viral AC1 protein are necessary and sufficient for the production of RDR intermediates. The consequences of an inherent geminiviral recombination activity for the use of pathogen-derived resistance traits are discussed.
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Affiliation(s)
- H Jeske
- Institute of Biology, Department of Molecular Biology and Plant Virology, University of Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany.
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N'Guessan P, Pinel A, Sy AA, Ghesquière A, Fargette D. Distribution, Pathogenicity, and Interactions of Two Strains of Rice yellow mottle virus in Forested and Savanna Zones of West Africa. PLANT DISEASE 2001; 85:59-64. [PMID: 30832072 DOI: 10.1094/pdis.2001.85.1.59] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In Côte d'Ivoire, the S2 strain of Rice yellow mottle virus (RYMV) predominated in the forested zones, including the "rice belt" to the west, in each of the cropping systems where rice was grown. The S1 strain occurred more frequently in the northern Guinean savanna, and only S1 isolates were found further north in the Sahelo-Soudanian zones. In mixed infection, S2 dominated over S1 both in viral capsid and RNA contents under temperature regimes encompassing those observed in savanna and forested zones of Côte d'Ivoire. There was no evidence of interactions in virus accumulation between the West African strains S1 or S2 with the more distantly related East African strain S4. Field trials emphasized the impact of RYMV, which induced yield losses of 40 to 60% in several widely grown cultivars of Oryza sativa indica and O. sativa japonica. We report the high resistance of the O. indica cv. Gigante under field conditions which was apparent with all the S1 and S2 isolates tested. Responses to RYMV infection of several cultivars were isolate dependent. With most differential cultivars, responses were not strain specific, with the exception of the O. japonica cv. Idsa6, in which the S2 isolates always induced higher yield losses than the S1 isolates.
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Affiliation(s)
| | - A Pinel
- LPRC, CIRAD-IRD, BP 5035, 34032 Montpellier cedex 1, France
| | - A A Sy
- ADRAO, BP 2551, Bouaké 01, Côte d'Ivoire
| | - A Ghesquière
- Genetrop, IRD, BP 5045, 34032 Montpellier cedex 1, France
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