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Kon T, Sato C, Fuji SI. Molecular characterization and host reaction to tomato mottle mosaic virus isolated from sweet pepper seeds in Japan. Arch Virol 2024; 169:113. [PMID: 38684570 DOI: 10.1007/s00705-024-06035-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 03/17/2024] [Indexed: 05/02/2024]
Abstract
Many countries have identified tomato mottle mosaic virus (ToMMV) as a serious threat to tomato production. Here, we constructed and characterized infectious clones of ToMMV isolated from Japanese sweet pepper seeds. The genome of the Japanese isolate is 6399 nucleotides in length and exhibits the highest identity with previously characterized isolates. For example, it is 99.7% identical to that of the Mauritius isolate, which occurs worldwide. Phylogenetic analysis based on complete genome sequences revealed that the Japanese isolates clustered in the same clade as those from other countries. When homozygous tomato cultivars with tobamovirus resistance genes were inoculated with an infectious cDNA clone of ToMMV, the virus systemically infected tomato plants with symptoms typical of Tm-1-carrying tomato cultivars. In contrast, tomato cultivars carrying Tm-2 or Tm-22 showed symptoms only on the inoculated leaves. Furthermore, when commercial cultivars of Tm-22 heterozygous tomato were inoculated with ToMMV, systemic infections were observed in all cultivars, with infection frequencies ranging from 25 to 100%. Inoculation of heterozygous sweet pepper cultivars with tobamovirus resistance genes (L1, L3, and L4) with ToMMV resulted in an infection frequency of about 70%, but most of the infected L1, L3, and L4 cultivars were symptomless, and 10-20% showed symptoms of necrosis and yellowing. Tomato mosaic virus strain L11A, an attenuated virus, did not provide cross-protection against ToMMV and led to systemic infection with typical symptoms. These results suggest that ToMMV might cause extensive damage to existing tomato and sweet pepper cultivars commonly grown in Japan.
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Affiliation(s)
- Tatsuya Kon
- Department of Biological Production, Faculty of Bioresource Sciences, Akita Prefectural University, 241-438 Kaidobata-Nishi, Nakano, Shimoshinjo, Akita, 010-0195, Japan.
| | - Chinami Sato
- Department of Biological Production, Faculty of Bioresource Sciences, Akita Prefectural University, 241-438 Kaidobata-Nishi, Nakano, Shimoshinjo, Akita, 010-0195, Japan
| | - Shin-Ichi Fuji
- Department of Biological Production, Faculty of Bioresource Sciences, Akita Prefectural University, 241-438 Kaidobata-Nishi, Nakano, Shimoshinjo, Akita, 010-0195, Japan
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Yang X, Luo X, Zhang Y, Zhang Z, OuYang X, Shi X, Lv X, Li F, Zhang S, Liu Y, Zhang D. Tomato chlorosis virus CPm protein is a pathogenicity determinant and suppresses host local RNA silencing induced by single-stranded RNA. Front Microbiol 2023; 14:1151747. [PMID: 37056753 PMCID: PMC10086252 DOI: 10.3389/fmicb.2023.1151747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 03/10/2023] [Indexed: 03/30/2023] Open
Abstract
IntroductionTomato chlorosis virus (ToCV) is a typical member of the genus Crinivirus, which severely threatens Solanaceae crops worldwide. The CPm protein encoded by ToCV has been reported to be associated with virus transmission by vectors and is involved in RNA silencing suppression, while the mechanisms remain ambiguous.MethodsHere, ToCV CPm was ectopically expressed by a Potato virus X (PVX) vector and infiltrated into Nicotiana benthamiana wild-type and GFP-transgenic16c plants.ResultsThe phylogenetic analysis showed that the CPm proteins encoded by criniviruses were distinctly divergent in amino acid sequences and predicted conserved domains, and the ToCV CPm protein possesses a conserved domain homologous to the TIGR02569 family protein, which does not occur in other criniviruses. Ectopic expression of ToCV CPm using a PVX vector resulted in severe mosaic symptoms followed by a hypersensitive-like response in N. benthamiana. Furthermore, agroinfiltration assays in N. benthamiana wilt type or GFP-transgenic 16c indicated that ToCV CPm protein effectively suppressed local RNA silencing induced by single-stranded but not double-stranded RNA, which probably resulted from the activity of binding double-stranded but not single-stranded RNA by ToCV CPm protein.ConclusionTaken together, the results of this study suggest that the ToCV CPm protein possesses the dual activities of pathogenicity and RNA silencing, which might inhibit host post-transcriptional gene silencing (PTGS)-mediated resistance and is pivotal in the primary process of ToCV infecting hosts.
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Affiliation(s)
- Xiao Yang
- Longping Branch, College of Biology, Hunan University, Changsha, Hunan, China
| | - Xiangwen Luo
- Longping Branch, College of Biology, Hunan University, Changsha, Hunan, China
- Key Laboratory of Pest Management of Horticultural Crop of Hunan Province, Hunan Plant Protection Institute, Hunan Academy of Agricultural Science, Changsha, Hunan, China
| | - Yu Zhang
- Key Laboratory of Pest Management of Horticultural Crop of Hunan Province, Hunan Plant Protection Institute, Hunan Academy of Agricultural Science, Changsha, Hunan, China
| | - Zhanhong Zhang
- Longping Branch, College of Biology, Hunan University, Changsha, Hunan, China
- Key Laboratory of Pest Management of Horticultural Crop of Hunan Province, Hunan Plant Protection Institute, Hunan Academy of Agricultural Science, Changsha, Hunan, China
| | - Xian OuYang
- Key Laboratory of Pest Management of Horticultural Crop of Hunan Province, Hunan Plant Protection Institute, Hunan Academy of Agricultural Science, Changsha, Hunan, China
| | - Xiaobin Shi
- Longping Branch, College of Biology, Hunan University, Changsha, Hunan, China
- Key Laboratory of Pest Management of Horticultural Crop of Hunan Province, Hunan Plant Protection Institute, Hunan Academy of Agricultural Science, Changsha, Hunan, China
| | - Xiaoyuan Lv
- Technical Center of Changsha Customs, Changsha, Hunan, China
| | - Fan Li
- College of Plant Protection, Yunnan Agricultural University, Kunming, China
| | - Songbai Zhang
- Longping Branch, College of Biology, Hunan University, Changsha, Hunan, China
- Key Laboratory of Pest Management of Horticultural Crop of Hunan Province, Hunan Plant Protection Institute, Hunan Academy of Agricultural Science, Changsha, Hunan, China
- *Correspondence: Songbai Zhang,
| | - Yong Liu
- Longping Branch, College of Biology, Hunan University, Changsha, Hunan, China
- Key Laboratory of Pest Management of Horticultural Crop of Hunan Province, Hunan Plant Protection Institute, Hunan Academy of Agricultural Science, Changsha, Hunan, China
- Yong Liu,
| | - Deyong Zhang
- Longping Branch, College of Biology, Hunan University, Changsha, Hunan, China
- Key Laboratory of Pest Management of Horticultural Crop of Hunan Province, Hunan Plant Protection Institute, Hunan Academy of Agricultural Science, Changsha, Hunan, China
- Deyong Zhang,
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Development of a Scoring System for Sugarcane Mosaic Disease and Genotyping of Sugarcane Germplasm for Mosaic Viruses. SUGAR TECH 2021. [DOI: 10.1007/s12355-021-00995-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Nabeshima T, Doi M, Hosokawa M. Comparative Analysis of Chrysanthemum Stunt Viroid Accumulation and Movement in Two Chrysanthemum ( Chrysanthemum morifolium) Cultivars with Differential Susceptibility to the Viroid Infection. FRONTIERS IN PLANT SCIENCE 2017; 8:1940. [PMID: 29250083 PMCID: PMC5715398 DOI: 10.3389/fpls.2017.01940] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 10/27/2017] [Indexed: 06/07/2023]
Abstract
Chrysanthemum stunt viroid (CSVd) was inoculated into two chrysanthemum (Chrysanthemum morifolium) cultivars, the CSVd-susceptible cultivar Piato and the CSVd-resistant cultivar Mari Kazaguruma. For CSVd inoculation, grafting and Agrobacterium-mediated inoculation were used. In grafting experiments, CSVd was detectable in Mari Kazaguruma after grafting onto infected Piato, but after removal of infected rootstocks, CSVd could not be detected in the uppermost leaves. In agroinfection experiments, CSVd systemic infection was observed in Piato but not in Mari Kazaguruma. However, agro-inoculated leaves of Mari Kazaguruma accumulated circular CSVd RNA to levels equivalent to those in Piato at 7 days post-inoculation. In situ detection of CSVd in inoculated leaves revealed that CSVd was absent in phloem of Mari Kazaguruma, while CSVd strongly localized to this site in Piato. We hypothesize that CSVd resistance in Mari Kazaguruma relates not to CSVd replication but to CSVd movement in leaves.
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Jada B, Soitamo AJ, Siddiqui SA, Murukesan G, Aro EM, Salakoski T, Lehto K. Multiple different defense mechanisms are activated in the young transgenic tobacco plants which express the full length genome of the Tobacco mosaic virus, and are resistant against this virus. PLoS One 2014; 9:e107778. [PMID: 25244327 PMCID: PMC4171492 DOI: 10.1371/journal.pone.0107778] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 08/16/2014] [Indexed: 11/18/2022] Open
Abstract
Previously described transgenic tobacco lines express the full length infectious Tobacco mosaic virus (TMV) genome under the 35S promoter (Siddiqui et al., 2007. Mol Plant Microbe Interact, 20: 1489-1494). Through their young stages these plants exhibit strong resistance against both the endogenously expressed and exogenously inoculated TMV, but at the age of about 7-8 weeks they break into TMV infection, with typical severe virus symptoms. Infections with some other viruses (Potato viruses Y, A, and X) induce the breaking of the TMV resistance and lead to synergistic proliferation of both viruses. To deduce the gene functions related to this early resistance, we have performed microarray analysis of the transgenic plants during the early resistant stage, and after the resistance break, and also of TMV-infected wild type tobacco plants. Comparison of these transcriptomes to those of corresponding wild type healthy plants indicated that 1362, 1150 and 550 transcripts were up-regulated in the transgenic plants before and after the resistance break, and in the TMV-infected wild type tobacco plants, respectively, and 1422, 1200 and 480 transcripts were down-regulated in these plants, respectively. These transcriptome alterations were distinctly different between the three types of plants, and it appears that several different mechanisms, such as the enhanced expression of the defense, hormone signaling and protein degradation pathways contributed to the TMV-resistance in the young transgenic plants. In addition to these alterations, we also observed a distinct and unique gene expression alteration in these plants, which was the strong suppression of the translational machinery. This may also contribute to the resistance by slowing down the synthesis of viral proteins. Viral replication potential may also be suppressed, to some extent, by the reduction of the translation initiation and elongation factors eIF-3 and eEF1A and B, which are required for the TMV replication complex.
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Affiliation(s)
- Balaji Jada
- Department of Biochemistry, Laboratory of Molecular Plant Biology, University of Turku, Turku, Finland
| | - Arto J. Soitamo
- Department of Biochemistry, Laboratory of Molecular Plant Biology, University of Turku, Turku, Finland
| | | | - Gayatri Murukesan
- Department of Information Technology, University of Turku, Turku, Finland
| | - Eva-Mari Aro
- Department of Biochemistry, Laboratory of Molecular Plant Biology, University of Turku, Turku, Finland
| | - Tapio Salakoski
- Department of Information Technology, University of Turku, Turku, Finland
| | - Kirsi Lehto
- Department of Biochemistry, Laboratory of Molecular Plant Biology, University of Turku, Turku, Finland
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Santovito E, Mascia T, Siddiqui SA, Minutillo SA, Valkonen JPT, Gallitelli D. Infection cycle of Artichoke Italian latent virus in tobacco plants: meristem invasion and recovery from disease symptoms. PLoS One 2014; 9:e99446. [PMID: 24911029 PMCID: PMC4050035 DOI: 10.1371/journal.pone.0099446] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 05/14/2014] [Indexed: 11/18/2022] Open
Abstract
Nepoviral infections induce recovery in fully expanded leaves but persist in shoot apical meristem (SAM) by a largely unknown mechanism. The dynamics of infection of a grapevine isolate of Artichoke Italian latent virus (AILV-V, genus Nepovirus) in tobacco plants, including colonization of SAM, symptom induction and subsequent recovery of mature leaves from symptoms, were characterized. AILV-V moved from the inoculated leaves systemically and invaded SAM in 7 days post-inoculation (dpi), remaining detectable in SAM at least up to 40 dpi. The new top leaves recovered from viral symptoms earliest at 21 dpi. Accumulation of viral RNA to a threshold level was required to trigger the overexpression of RDR6 and DCL4. Consequently, accumulation of viral RNA decreased in the systemically infected leaves, reaching the lowest concentration in the 3rd and 4th leaves at 23 dpi, which was concomitant with recovery of the younger, upper leaves from disease symptoms. No evidence of virus replication was found in the recovered leaves, but they contained infectious virus particles and were protected against re-inoculation with AILV-V. In this study we also showed that AILV-V did not suppress initiation or maintenance of RNA silencing in transgenic plants, but was able to interfere with the cell-to-cell movement of the RNA silencing signal. Our results suggest that AILV-V entrance in SAM and activation of RNA silencing may be distinct processes since the latter is triggered in fully expanded leaves by the accumulation of viral RNA above a threshold level rather than by virus entrance in SAM.
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Affiliation(s)
- Elisa Santovito
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, Università degli Studi di Bari Aldo Moro, Bari, Italy
| | - Tiziana Mascia
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, Università degli Studi di Bari Aldo Moro, Bari, Italy
- Istituto di Virologia vegetale del Consiglio Nazionale della Ricerca, Unità Operativa di Supporto di Bari, Bari, Italy
| | - Shahid A. Siddiqui
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
| | - Serena Anna Minutillo
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, Università degli Studi di Bari Aldo Moro, Bari, Italy
| | - Jari P. T. Valkonen
- Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
| | - Donato Gallitelli
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, Università degli Studi di Bari Aldo Moro, Bari, Italy
- Istituto di Virologia vegetale del Consiglio Nazionale della Ricerca, Unità Operativa di Supporto di Bari, Bari, Italy
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Mochizuki T, Yamazaki R, Wada T, Ohki ST. Coat protein mutations in an attenuated Cucumber mosaic virus encoding mutant 2b protein that lacks RNA silencing suppressor activity induces chlorosis with photosynthesis gene repression and chloroplast abnormalities in infected tobacco plants. Virology 2014; 456-457:292-9. [PMID: 24889248 DOI: 10.1016/j.virol.2014.04.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 03/23/2014] [Accepted: 04/06/2014] [Indexed: 10/25/2022]
Abstract
In tobacco plants, the Cucumber mosaic virus (CMV) pepo strain induces mosaic symptoms, including pale green chlorosis and malformed tissues. Here, we characterized the involvement of 2b protein and coat protein (CP) in the development of mosaic symptoms. A 2b mutant (R46C) that lacks viral suppressor of RNA silencing (VSR) activity showed an asymptomatic phenotype with low levels of virus accumulation. Tomato spotted wilt virus NSs protein did not complement the virulence of the R46C, although it did restore high-level virus accumulation. However, R46C mutants expressing mutated CP in which the amino acid P129 was mutated to A, E, C, Q, or S induced chlorosis that was associated with reduced expression of chloroplast and photosynthesis related genes (CPRGs) and abnormal chloroplasts with fewer thylakoid membranes. These results suggest that the CP of the CMV pepo strain acquires virulence by amino acid mutations, which causes CPRG repression and chloroplast abnormalities.
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Affiliation(s)
- Tomofumi Mochizuki
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1, Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
| | - Ryota Yamazaki
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1, Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Tomoya Wada
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1, Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Satoshi T Ohki
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1, Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
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Mochizuki T, Ogata Y, Hirata Y, Ohki ST. Quantitative transcriptional changes associated with chlorosis severity in mosaic leaves of tobacco plants infected with Cucumber mosaic virus. MOLECULAR PLANT PATHOLOGY 2014; 15:242-54. [PMID: 24745045 PMCID: PMC6638806 DOI: 10.1111/mpp.12081] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Cucumber mosaic virus (CMV) causes mosaic disease in inoculated tobacco plants. Coat protein (CP) is one of the major virulence determinants of CMV, and an amino acid substitution at residue 129 in CP alters the severity of chlorosis, such as pale green chlorosis and white chlorosis, in symptomatic tissues of mosaic leaves of infected tobacco. In this study, we compared the transcriptomes of chlorotic tissues infected with the wild-type pepo strain of CMV and two strains carrying CP mutants with diverse chlorosis severity. Differential gene expression analysis showed that CMV inoculation appeared to have similar effects on the transcriptional expression profiles of the symptomatic chlorotic tissues, and only the magnitude of expression differed among the different CMVs. Gene ontology analysis with biological process and cellular component terms revealed that many nuclear genes related to abiotic stress responses, including responses to cadmium, heat, cold and salt, were up-regulated, whereas chloroplast- and photosynthesis-related genes (CPRGs) were down-regulated, in the chlorotic tissues. Interestingly, the level of CPRG down-regulation was correlated with the severity of chlorosis. These results indicate that CP mutation governs the repression level and mRNA accumulation of CPRGs, which are closely associated with the induction of chlorosis.
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Wang MB, Masuta C, Smith NA, Shimura H. RNA silencing and plant viral diseases. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:1275-85. [PMID: 22670757 DOI: 10.1094/mpmi-04-12-0093-cr] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
RNA silencing plays a critical role in plant resistance against viruses, with multiple silencing factors participating in antiviral defense. Both RNA and DNA viruses are targeted by the small RNA-directed RNA degradation pathway, with DNA viruses being also targeted by RNA-directed DNA methylation. To evade RNA silencing, plant viruses have evolved a variety of counter-defense mechanisms such as expressing RNA-silencing suppressors or adopting silencing-resistant RNA structures. This constant defense-counter defense arms race is likely to have played a major role in defining viral host specificity and in shaping viral and possibly host genomes. Recent studies have provided evidence that RNA silencing also plays a direct role in viral disease induction in plants, with viral RNA-silencing suppressors and viral siRNAs as potentially the dominant players in viral pathogenicity. However, questions remain as to whether RNA silencing is the principal mediator of viral pathogenicity or if other RNA-silencing-independent mechanisms also account for viral disease induction. RNA silencing has been exploited as a powerful tool for engineering virus resistance in plants as well as in animals. Further understanding of the role of RNA silencing in plant-virus interactions and viral symptom induction is likely to result in novel anti-viral strategies in both plants and animals.
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Affiliation(s)
- Ming-Bo Wang
- CSIRO Division of Plant Industry, Canberra, Australia.
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MacDiarmid RM. Chimeric, infectious, and stable virus transcripts to study RNA silencing in "dark green" islands. Methods Mol Biol 2012; 894:299-308. [PMID: 22678588 DOI: 10.1007/978-1-61779-882-5_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Dark green islands (DGIs) form in some plant virus infections as areas that are resistant to infection. This resistance has been demonstrated to act through a sequence-specific, RNA degradation mechanism termed RNAi. In addition to the virus that induces the initial DGI, a second, infectious virus transcript carrying additional sequence of the initial virus can be used to dissect the RNAi mechanism of DGIs. The methods used to create stable, infectious transcripts that can carry heterologous sequences are described.
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Affiliation(s)
- Robin M MacDiarmid
- The New Zealand Institute of Plant and Food Research Limited, Auckland, New Zealand.
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Jovel J, Walker M, Sanfaçon H. Salicylic acid-dependent restriction of Tomato ringspot virus spread in tobacco is accompanied by a hypersensitive response, local RNA silencing, and moderate systemic resistance. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:706-18. [PMID: 21281112 DOI: 10.1094/mpmi-09-10-0224] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Tomato ringspot virus (ToRSV, a Nepovirus sp.) systemically infects many herbaceous plants. Viral RNA accumulates in symptomatic leaves and in young, asymptomatic leaves that emerge late in infection. Here, we show that systemic infection by ToRSV is restricted in tobacco. After an initial hypersensitive response in inoculated leaves, only a few plants showed limited systemic symptoms. Viral RNA did not usually accumulate to detectable levels in asymptomatic leaves. ToRSV-derived small-interfering RNAs and PR1a transcripts were only detected in tissues that contained viral RNA, indicating local induction of RNA silencing and salicylic acid (SA)-dependent defense responses. Lesion size and viral systemic spread were reduced with SA pretreatment but enhanced in NahG transgenic lines deficient in SA accumulation, suggesting that SA-dependent mechanisms play a key role in limiting ToRSV spread in tobacco. Restriction of virus infection was enhanced in transgenic lines expressing the P1-HC-Pro suppressor of silencing. Knocking down the SA-inducible RNA-dependent RNA polymerase 1 exacerbated the necrotic reaction but did not affect viral systemic spread. ToRSV-infected tobacco plants were susceptible to reinoculation by ToRSV or Tobacco mosaic virus, although a small reduction in lesion size was observed. This moderate systemic resistance suggests inefficient induction or spread of RNA silencing and systemic acquired resistance signal molecules.
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Affiliation(s)
- Juan Jovel
- Pacific Agri-Food Research Centre, Agriculture and Agri-Food, Canada
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Kobayashi M, Seo S, Hirai K, Yamamoto-Katou A, Katou S, Seto H, Meshi T, Mitsuhara I, Ohashi Y. Silencing of WIPK and SIPK mitogen-activated protein kinases reduces tobacco mosaic virus accumulation but permits systemic viral movement in tobacco possessing the N resistance gene. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1032-41. [PMID: 20615114 DOI: 10.1094/mpmi-23-8-1032] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Infection of tobacco cultivars possessing the N resistance gene with Tobacco mosaic virus (TMV) results in confinement of the virus by necrotic lesions at the infection site. Although the mitogen-activated protein kinases WIPK and SIPK have been implicated in TMV resistance, evidence linking them directly to disease resistance is, as yet, insufficient. Viral multiplication was reduced slightly in WIPK- or SIPK-silenced plants but substantially in WIPK/SIPK-silenced plants, and was correlated with an increase in salicylic acid (SA) and a decrease in jasmonic acid (JA). Silencing of WIPK and SIPK in a tobacco cultivar lacking the N gene did not inhibit viral accumulation. The reduction in viral accumulation was attenuated by expressing a gene for an SA-degrading enzyme or by exogenously applying JA. Inoculation of lower leaves resulted in the systemic spread of TMV and formation of necrotic lesions in uninoculated upper leaves. These results suggested that WIPK and SIPK function to negatively regulate local resistance to TMV accumulation, partially through modulating accumulation of SA and JA in an N-dependent manner, but positively regulate systemic resistance.
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Affiliation(s)
- Michie Kobayashi
- National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
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Calvo M, Dujovny G, Lucini C, Ortuño J, Alamillo JM, Simón-Mateo C, López-Moya JJ, García JA. Constraints to virus infection in Nicotiana benthamiana plants transformed with a potyvirus amplicon. BMC PLANT BIOLOGY 2010; 10:139. [PMID: 20604920 PMCID: PMC3095287 DOI: 10.1186/1471-2229-10-139] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Accepted: 07/06/2010] [Indexed: 05/24/2023]
Abstract
BACKGROUND Plant genomes have been transformed with full-length cDNA copies of viral genomes, giving rise to what has been called 'amplicon' systems, trying to combine the genetic stability of transgenic plants with the elevated replication rate of plant viruses. However, amplicons' performance has been very variable regardless of the virus on which they are based. This has boosted further interest in understanding the underlying mechanisms that cause this behavior differences, and in developing strategies to control amplicon expression. RESULTS Nicotiana benthamiana plants were transformed with an amplicon consisting of a full-length cDNA of the potyvirus Plum pox virus (PPV) genome modified to include a GFP reporter gene. Amplicon expression exhibited a great variability among different transgenic lines and even among different plants of the same line. Plants of the line 10.6 initially developed without signs of amplicon expression, but at different times some of them started to display sporadic infection foci in leaves approaching maturity. The infection progressed systemically, but at later times the infected plants recovered and returned to an amplicon-inactive state. The failure to detect virus-specific siRNAs in 10.6 plants before amplicon induction and after recovery suggested that a strong amplicon-specific RNA silencing is not established in these plants. However, the coexpression of extra viral silencing suppressors caused some amplicon activation, suggesting that a low level of RNA silencing could be contributing to maintain amplicon repression in the 10.6 plants. The resistance mechanisms that prevent amplicon-derived virus infection were also active against exogenous PPV introduced by mechanical inoculation or grafting, but did not affect other viruses. Amplicon-derived PPV was able to spread into wild type scions grafted in 10.6 rootstocks that did not display signs of amplicon expression, suggesting that resistance has little effect on virus movement. CONCLUSIONS Our results suggest that amplicon-derived virus infection is limited in this particular transgenic line by a combination of factors, including the presumed low efficiency of the conversion from the transgene transcript to replicable viral RNA, and also by the activation of RNA silencing and other defensive responses of the plant, which are not completely neutralized by viral suppressors.
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Affiliation(s)
- María Calvo
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Gabriela Dujovny
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Cristina Lucini
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Facultad de Ciencias y Artes, Universidad Católica de Ávila, Ávila, Spain
| | - Jesús Ortuño
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Josefa M Alamillo
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Departamento de Fisiología Vegetal, Facultad de Ciencias, Universidad de Córdoba, Córdoba, Spain
| | - Carmen Simón-Mateo
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Juan José López-Moya
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centre for Research in Agricultural Genomics CRAG, CSIC-IRTA-UAB, Barcelona, Spain
| | - Juan Antonio García
- Centro Nacional de Biotecnología-CSIC, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain
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Groenenboom MAC, Hogeweg P. RNA silencing can explain chlorotic infection patterns on plant leaves. BMC SYSTEMS BIOLOGY 2008; 2:105. [PMID: 19040760 PMCID: PMC2633331 DOI: 10.1186/1752-0509-2-105] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Accepted: 11/30/2008] [Indexed: 12/31/2022]
Abstract
Background RNA silencing has been implicated in virus symptom development in plants. One common infection symptom in plants is the formation of chlorotic tissue in leaves. Chlorotic and healthy tissue co-occur on a single leaf and form patterns. It has been shown that virus levels in chlorotic tissue are high, while they are low in healthy tissue. Additionally, the presence of siRNAs is confined to the chlorotic spots and the boundaries between healthy and infected tissue. These results strongly indicate that the interaction between virus growth and RNA silencing plays a role in the formation of infection patterns on leaves. However, how RNA silencing leads to the intricate patterns is not known. Results Here we elucidate the mechanisms leading to infection patterns and the conditions which lead to the various patterns observed. We present a modeling approach in which we combine intra- and inter-cellular dynamics of RNA silencing and viral growth. We observe that, due to the spread of viruses and the RNA silencing response, parts of the tissue become infected while other parts remain healthy. As is observed in experiments high virus levels coincide with high levels of siRNAs, and siRNAs are also present in the boundaries between infected and healthy tissue. We study how single- and double-stranded cleavage by Dicer and amplification by RNA-dependent RNA polymerase can affect the patterns formed. Conclusion This work shows that RNA silencing and virus growth within a cell, and the local spread of virions and siRNAs between cells can explain the heterogeneous spread of virus in leaf tissue, and therewith the observed infection patterns in plants.
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Affiliation(s)
- Marian A C Groenenboom
- Theoretical Biology and Bioinformatics, University of Utrecht, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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Díaz-Pendón JA, Ding SW. Direct and indirect roles of viral suppressors of RNA silencing in pathogenesis. ANNUAL REVIEW OF PHYTOPATHOLOGY 2008; 46:303-26. [PMID: 18680427 DOI: 10.1146/annurev.phyto.46.081407.104746] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Plant and animal viruses overcome host antiviral silencing by encoding diverse viral suppressors of RNA silencing (VSRs). Prior to the identification and characterization of their silencing suppression activities mostly in transgene silencing assays, plant VSRs were known to enhance virus accumulation in the inoculated protoplasts, promote cell-to-cell virus movement in the inoculated leaves, facilitate the phloem-dependent long-distance virus spread, and/or intensify disease symptoms in systemically infected tissues. Here we discuss how the various silencing suppression activities of VSRs may facilitate these distinct steps during plant infection and why VSRs may not play a direct role in eliciting disease symptoms by general impairments of host endogenous small RNA pathways. We also highlight many of the key questions still to be addressed on the role of viral suppression of antiviral silencing in plant infection.
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Affiliation(s)
- Juan A Díaz-Pendón
- Center for Plant Cell Biology, Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521, USA.
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