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Park TS, Min DJ, Park JS, Hong JS. The N-Terminal Region of Cucumber Mosaic Virus 2a Protein Is Involved in the Systemic Infection in Brassica juncea. PLANTS (BASEL, SWITZERLAND) 2024; 13:1001. [PMID: 38611534 PMCID: PMC11013781 DOI: 10.3390/plants13071001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 03/29/2024] [Accepted: 03/29/2024] [Indexed: 04/14/2024]
Abstract
Brassica juncea belongs to the Brassicaceae family and is used as both an oilseed and vegetable crop. As only a few studies have reported on the cucumber mosaic virus (CMV) in B. juncea, we conducted this study to provide a basic understanding of the B. juncea and CMV interactions. B. juncea-infecting CMV (CMV-Co6) and non-infecting CMV (CMV-Rs1) were used. To identify the determinants of systemic infection in B. juncea, we first constructed infectious clones of CMV-Co6 and CMV-Rs1 and used them as pseudo-recombinants. RNA2 of CMV was identified as an important determinant in B. juncea because B. juncea were systemically infected with RNA2-containing pseudo-recombinants; CMV-Co6, R/6/R, and R/6/6 were systemically infected B. juncea. Subsequently, the amino acids of the 2a and 2b proteins were compared, and a chimeric clone was constructed. The chimeric virus R/6Rns/R6cp, containing the C-terminal region of the 2a protein of CMV-Rs1, still infects B. juncea. It is the 2a protein that determines the systemic CMV infection in B. juncea, suggesting that conserved 160G and 214A may play a role in systemic CMV infection in B. juncea.
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Affiliation(s)
| | | | | | - Jin-Sung Hong
- Interdisciplinary Program in Smart Agriculture, Kangwon National University, Chuncheon 24341, Republic of Korea; (T.-S.P.); (D.-J.M.); (J.-S.P.)
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Cheng Y, Zheng T, Yang D, Peng Q, Dong J, Xi D. Cucumber mosaic virus impairs the physiological homeostasis of Panax notoginseng and induces saponin-mediated resistance. Virology 2024; 591:109983. [PMID: 38237218 DOI: 10.1016/j.virol.2024.109983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 12/24/2023] [Accepted: 01/04/2024] [Indexed: 01/29/2024]
Abstract
As an important medicinal plant, Panax notoginseng often suffers from various abiotic and biotic stresses during its growth, such as drought, heavy metals, fungi, bacteria and viruses. In this study, the symptom and physiological parameters of cucumber mosaic virus (CMV)-infected P. notoginseng were analyzed and the RNA-seq was performed. The results showed that CMV infection affected the photosynthesis of P. notoginseng, caused serious oxidative damage to P. notoginseng and increased the activity of several antioxidant enzymes. Results of transcriptome analysis and corresponding verification showed that CMV infection changed the expression of genes related to plant defense and promoted the synthesis of P. notoginseng saponins to a certain extent, which may be defensive ways of P. notoginseng against CMV infection. Furthermore, pretreatment plants with saponins reduced the accumulation of CMV. Thus, our results provide new insights into the role of saponins in P. notoginseng response to virus infection.
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Affiliation(s)
- Yongchao Cheng
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, PR China
| | - Tianrui Zheng
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, PR China
| | - Daoyong Yang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, PR China
| | - Qiding Peng
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, PR China
| | - Jiahong Dong
- School of Chinese Materia Medica and Yunnan Key Laboratory of Southern Medicinal Resource, Yunnan University of Chinese Medicine, Kunming, 650500, PR China
| | - Dehui Xi
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, PR China.
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Marttinen EM, Lehtonen MT, van Gessel N, Reski R, Valkonen JPT. Viral suppressor of RNA silencing in vascular plants also interferes with the development of the bryophyte Physcomitrella patens. PLANT, CELL & ENVIRONMENT 2022; 45:220-235. [PMID: 34564869 PMCID: PMC9135061 DOI: 10.1111/pce.14194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 09/13/2021] [Accepted: 09/15/2021] [Indexed: 06/13/2023]
Abstract
Plant viruses are important pathogens able to overcome plant defense mechanisms using their viral suppressors of RNA silencing (VSR). Small RNA pathways of bryophytes and vascular plants have significant similarities, but little is known about how viruses interact with mosses. This study elucidated the responses of Physcomitrella patens to two different VSRs. We transformed P. patens plants to express VSR P19 from tomato bushy stunt virus and VSR 2b from cucumber mosaic virus, respectively. RNA sequencing and quantitative PCR were used to detect the effects of VSRs on gene expression. Small RNA (sRNA) sequencing was used to estimate the influences of VSRs on the sRNA pool of P. patens. Expression of either VSR-encoding gene caused developmental disorders in P. patens. The transcripts of four different transcription factors (AP2/erf, EREB-11 and two MYBs) accumulated in the P19 lines. sRNA sequencing revealed that VSR P19 significantly changed the microRNA pool in P. patens. Our results suggest that VSR P19 is functional in P. patens and affects the abundance of specific microRNAs interfering with gene expression. The results open new opportunities for using Physcomitrella as an alternative system to study plant-virus interactions.
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Affiliation(s)
- Eeva M. Marttinen
- Department of Agricultural SciencesUniversity of HelsinkiHelsinkiFinland
| | - Mikko T. Lehtonen
- Department of Agricultural SciencesUniversity of HelsinkiHelsinkiFinland
- Plant Analytics UnitFinnish Food AuthorityHelsinkiFinland
| | - Nico van Gessel
- Plant Biotechnology, Faculty of BiologyUniversity of FreiburgFreiburgGermany
| | - Ralf Reski
- Plant Biotechnology, Faculty of BiologyUniversity of FreiburgFreiburgGermany
- Signalling Research Centres BIOSS and CIBSSUniversity of FreiburgFreiburgGermany
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Ghosh D, M M, Chakraborty S. Impact of viral silencing suppressors on plant viral synergism: a global agro-economic concern. Appl Microbiol Biotechnol 2021; 105:6301-6313. [PMID: 34423406 DOI: 10.1007/s00253-021-11483-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 12/27/2022]
Abstract
Plant viruses are known for their devastating impact on global agriculture. These intracellular biotrophic pathogens can infect a wide variety of plant hosts all over the world. The synergistic association of plant viruses makes the situation more alarming. It usually promotes the replication, movement, and transmission of either or both the coexisting synergistic viral partners. Although plants elicit a robust antiviral immune reaction, including gene silencing, to limit these infamous invaders, viruses counter it by encoding viral suppressors of RNA silencing (VSRs). Growing evidence also suggests that VSRs play a driving role in mediating the plant viral synergism. This review briefly discusses the evil impacts of mixed infections, especially synergism, and then comprehensively describes the emerging roles of VSRs in mediating the synergistic association of plant viruses. KEY POINTS: • Synergistic associations of plant viruses have devastating impacts on global agriculture. • Viral suppressors of RNA silencing (VSRs) play key roles in driving plant viral synergism.
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Affiliation(s)
- Dibyendu Ghosh
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Malavika M
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
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Lee SC, Pai H, Huang YW, He MH, Song YL, Kuo SY, Chang WC, Hsu YH, Lin NS. Exploring the Multifunctional Roles of Odontoglossum Ringspot Virus P126 in Facilitating Cymbidium Mosaic Virus Cell-to-Cell Movement during Mixed Infection. Viruses 2021; 13:1552. [PMID: 34452417 PMCID: PMC8402721 DOI: 10.3390/v13081552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 12/11/2022] Open
Abstract
Synergistic interactions among viruses, hosts and/or transmission vectors during mixed infection can alter viral titers, symptom severity or host range. Viral suppressors of RNA silencing (VSRs) are considered one of such factors contributing to synergistic responses. Odontoglossum ringspot virus (ORSV) and cymbidium mosaic virus (CymMV), which are two of the most significant orchid viruses, exhibit synergistic symptom intensification in Phalaenopsis orchids with unilaterally enhanced CymMV movement by ORSV. In order to reveal the underlying mechanisms, we generated infectious cDNA clones of ORSV and CymMV isolated from Phalaenopsis that exerted similar unilateral synergism in both Phalaenopsis orchid and Nicotiana benthamiana. Moreover, we show that the ORSV replicase P126 is a VSR. Mutagenesis analysis revealed that mutation of the methionine in the carboxyl terminus of ORSV P126 abolished ORSV replication even though some P126 mutants preserved VSR activity, indicating that the VSR function of P126 alone is not sufficient for viral replication. Thus, P126 functions in both ORSV replication and as a VSR. Furthermore, P126 expression enhanced cell-to-cell movement and viral titers of CymMV in infected Phalaenopsis flowers and N. benthamiana leaves. Taking together, both the VSR and protein function of P126 might be prerequisites for unilaterally enhancing CymMV cell-to-cell movement by ORSV.
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Affiliation(s)
- Shu-Chuan Lee
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-C.L.); (H.P.); (M.-H.H.); (Y.-L.S.)
| | - Hsuan Pai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-C.L.); (H.P.); (M.-H.H.); (Y.-L.S.)
| | - Ying-Wen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan; (Y.-W.H.); (S.-Y.K.); (Y.-H.H.)
| | - Meng-Hsun He
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-C.L.); (H.P.); (M.-H.H.); (Y.-L.S.)
| | - Yun-Lin Song
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-C.L.); (H.P.); (M.-H.H.); (Y.-L.S.)
| | - Song-Yi Kuo
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan; (Y.-W.H.); (S.-Y.K.); (Y.-H.H.)
| | - Wen-Chi Chang
- College of Biosciences and Biotechnology, Institute of Tropical Plant Sciences, National Cheng Kung University, Tainan 70101, Taiwan;
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan; (Y.-W.H.); (S.-Y.K.); (Y.-H.H.)
| | - Na-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan; (S.-C.L.); (H.P.); (M.-H.H.); (Y.-L.S.)
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Wang X, Luo C, Xu Y, Zhang C, Bao M, Dou J, Wang Q, Cheng Y. Expression of the p24 silencing suppressor of Grapevine leafroll-associated virus 2 from Potato virus X or Barley stripe mosaic virus vector elicits hypersensitive responses in Nicotiana benthamiana. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2019; 142:34-42. [PMID: 31255907 DOI: 10.1016/j.plaphy.2019.06.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/24/2019] [Accepted: 06/23/2019] [Indexed: 06/09/2023]
Abstract
The 24-kDa protein (p24) encoded by Grapevine leafroll-associated virus 2 (GLRaV-2) is an RNA-silencing suppressor (RSS), but its effect on active viral infection is unclear. Using a Potato virus X (PVX)-based expression system, we demonstrated that p24 elicits lethal systemic necrosis in Nicotiana benthamiana, sharing typical characteristics of the hypersensitive response (HR), and that NbRAR1 (a cytoplasmic Zn2+-binding protein) is involved in the PVX-p24-mediated systemic necrosis. Moreover, expression of p24 from Barley stripe mosaic virus (BSMV) vector triggered local necrosis in infiltrated patches of N. benthamiana, likely inhibiting viral systemic spread. By deletion analysis, we demonstrated that amino acids (aa) 1 to 180, which are located in the region (aa 1-188) previously shown to be necessary for p24's RSS activity, is sufficient for p24 to elicit systemic necrosis in the context of PVX infection. Using substitution mutants, we revealed that silencing-suppression-defective mutants R2A and W54A induce only a mild necrotic response; two mutants without self-interaction ability previously shown to lose or retain weak suppression function also displayed decreased pathogenicity: W149A without RSS activity elicited a mild necrotic response, whereas V162H/L169H/L170H which retains weak RSS activity was able to induce systemic necrosis, but with a 1- to 2-day delay. Taken together, p24 plays an important role in GLRaV-2 pathogenesis, triggering HR-like necrosis in N. benthamiana plants when expressed from PVX or BSMV vector; both the silencing suppression and self-interaction are crucial for p24's pathogenicity activity, and the region of p24 for determining systemic necrosis is mapped to aa 1-180.
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Affiliation(s)
- Xianyou Wang
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China
| | - Chen Luo
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China
| | - Yanfei Xu
- DeLaval Tianjin Company, Tianjin, 300308, China
| | - Chenwei Zhang
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China
| | - Mian Bao
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China
| | - Junjie Dou
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China
| | - Qi Wang
- Department of Plant Pathology, China Agricultural University, Beijing, 100193, China
| | - Yuqin Cheng
- Department of Pomology, China Agricultural University, Beijing, 100193, China; Key Laboratory of Viticulture and Enology, Ministry of Agriculture, Beijing, 100083, China.
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Reactivation of rolB transgene expression in Vitis amurensis Rupr. cells upon retransformation with 2b gene from Cucumovirus isolate NK. Biotechnol Lett 2019; 41:443-451. [PMID: 30603831 DOI: 10.1007/s10529-018-02642-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 12/19/2018] [Indexed: 10/27/2022]
Abstract
OBJECTIVE Studies concerning 2b protein from Cucumovirus showed 2b to effectively repress functioning of the plant silencing complex, current study aimed whether retransformation with 2b gene able to restore silenced transgene expression in plant cells. RESULTS A rolB-transgenic cell culture of Vitis amurensis Rupr. that was continuously subcultured during more than 10 years and exhibited decreased transcription of the rolB transgene was retransformed with the 2b gene of Cucumovirus-NK. Three cell lines retransformed with 2b showed a significant up-regulation of rolB expression accompanied with enhancements in their stilbenes content level in more than 2,7-fold compared to parental rolB-transgenic cell line. The mentioned increase in the level of stilbenes content was due to activation of certain stilbene synthase genes expression responsible for stilbenes biosynthesis in V. amurensis cells. Restoration of rolB expression upon 2b-retransformation led to increase in the expression levels of VaSTS2-VaSTS5 and VaSTS7 isoforms. CONCLUSIONS 2b from CMV-NK can reactivate a silenced transgene expression, even after 10 years of subcultivation, nevertheless, optimization of the methods concerning 2b introduction in plant genomes is necessary to avoid undesirable silencing effects.
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Senanayake DMJB, Mandal B. Expression of symptoms, viral coat protein and silencing suppressor gene during mixed infection of a N-Wi strain of potato virus Y and an asymptomatic strain of potato virus X. Virusdisease 2015; 25:314-21. [PMID: 25674598 DOI: 10.1007/s13337-014-0204-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 02/07/2014] [Indexed: 11/26/2022] Open
Abstract
Potato virus Y (PVY) and potato virus X (PVX), the RNA viruses of two different genera results into synergistic interactions on mixed infection. In this study, a N-Wi strain of PVY and a PVX strain that is asymptomatic on potato were used to study their interactions during mixed infection in Nicotiana benthamiana and Nicotiana tabacum with reference to symptom expression, level of coat protein (CP) using ELISA and suppressor gene using real time PCR under high temperature (26-40 °C) and low temperature (5-25 °C) conditions. Both mixed and single infection caused severe necrosis and death of N. benthamiana plants. Single infection of these viruses in N. tabacum showed mild symptoms but mixed infection caused more severe symptoms. Synergistic symptoms were more pronounced under low temperature conditions than at high temperature. In low temperature conditions, the CP level of PVX in N. benthamiana was twofold higher than PVY and both the viruses reached at peak at 28 dpi in single virus infection. When PVY and PVX inoculated together, the CP levels of both the viruses increased and reached to the peak earlier (within 7-14 days) than that in the single virus inoculation. Although, the CP level of PVX was higher than PVY in mixed infection, at later stage (28 dpi) both the CP level declined to the similar level. The level of p25 suppressor gene was higher than HC-Pro in single inoculation. However, under mixed inoculation of PVY and PVX, expression of p25 was declined to the level of HC-Pro when the CP levels of both the virus also were observed to decline. The expression pattern of CP and suppressor gene was different in plants when mixed infection was created by inoculation of one virus followed by the other. This study showed the level of CP and suppressor gene of specific strain of PVY and PVX during their mixed infection in tobacco.
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Affiliation(s)
- D M J B Senanayake
- Advanced Centre for Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, 110012 India
| | - B Mandal
- Advanced Centre for Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, 110012 India
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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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The capsid protein p38 of turnip crinkle virus is associated with the suppression of cucumber mosaic virus in Arabidopsis thaliana co-infected with cucumber mosaic virus and turnip crinkle virus. Virology 2014; 462-463:71-80. [DOI: 10.1016/j.virol.2014.05.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/09/2014] [Accepted: 05/27/2014] [Indexed: 11/20/2022]
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Bag S, Mitter N, Eid S, Pappu HR. Complementation between two tospoviruses facilitates the systemic movement of a plant virus silencing suppressor in an otherwise restrictive host. PLoS One 2012; 7:e44803. [PMID: 23077485 PMCID: PMC3473055 DOI: 10.1371/journal.pone.0044803] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 08/14/2012] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND New viruses pathogenic to plants continue to emerge due to mutation, recombination, or reassortment among genomic segments among individual viruses. Tospoviruses cause significant economic damage to a wide range of crops in many parts of the world. The genetic or molecular basis of the continued emergence of new tospoviruses and new hosts is not well understood though it is generally accepted that reassortment and/or genetic complementation among the three genomic segments of individual viruses could be contributing to this variability since plants infected with more than one tospovirus are not uncommon in nature. METHODOLOGY/PRINCIPAL FINDINGS Two distinct and economically important tospoviruses, Iris yellow spot virus (IYSV) and Tomato spotted wilt virus (TSWV), were investigated for inter-virus interactions at the molecular level in dually-infected plants. Datura (Datura stramonium) is a permissive host for TSWV, while it restricts the movement of IYSV to inoculated leaves. In plants infected with both viruses, however, TSWV facilitated the selective movement of the viral gene silencing suppressor (NSs) gene of IYSV to the younger, uninoculated leaves. The small RNA expression profiles of IYSV and TSWV in single- and dually-infected datura plants showed that systemic leaves of dually-infected plants had reduced levels of TSWV N gene-specific small interfering RNAs (siRNAs). No TSWV NSs-specific siRNAs were detected either in the inoculated or systemic leaves of dually-infected datura plants indicating a more efficient suppression of host silencing machinery in the presence of NSs from both viruses as compared to the presence of only TSWV NSs. CONCLUSION/SIGNIFICANCE Our study identifies a new role for the viral gene silencing suppressor in potentially modulating the biology and host range of viruses and underscores the importance of virally-coded suppressors of gene silencing in virus infection of plants. This is the first experimental evidence of functional complementation between two distinct tospoviruses in the Bunyaviridae family.
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Affiliation(s)
- Sudeep Bag
- Department of Plant Pathology, Washington State University, Pullman, Washington, United States of America
| | - Neena Mitter
- Queensland Alliance for Agriculture and Food Innovation, University of Queensland, St. Lucia, Queensland, Australia
| | - Sahar Eid
- Department of Plant Pathology, Washington State University, Pullman, Washington, United States of America
| | - Hanu R. Pappu
- Department of Plant Pathology, Washington State University, Pullman, Washington, United States of America
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Mochizuki T, Ohki ST. Cucumber mosaic virus: viral genes as virulence determinants. MOLECULAR PLANT PATHOLOGY 2012; 13:217-25. [PMID: 21980997 PMCID: PMC6638793 DOI: 10.1111/j.1364-3703.2011.00749.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
TAXONOMIC RELATIONSHIPS Cucumber mosaic virus (CMV) is the type species of the genus Cucumovirus in the family Bromoviridae, which also encompasses the Peanut stunt virus (PSV) and the Tomato aspermy virus (TAV). Nucleotide sequence similarity among these three cucumoviruses is 60%-65%. CMV strains are divided into three subgroups, IA, IB and II, based on the sequence of the 5' untranslated region of the genomic RNA 3. Overall nucleotide sequence similarity among CMV strains is approximately 70%-98%. GEOGRAPHICAL DISTRIBUTION, HOST RANGE AND SYMPTOMATOLOGY: CMV is distributed worldwide, primarily in temperate to tropical climate zones. CMV infects more than 1200 species of 100 plant families, including monocot and dicot plants. Symptoms caused by CMV infection vary with the host species and/or CMV strain, and include mosaic, stunt, chlorosis, dwarfing, leaf malformation and systemic necrosis. CMV disease is spread primarily by aphid transmission in a nonpersistent manner. PHYSICAL PROPERTIES In tobacco sap, the thermal inactivation point of the viral infectivity is approximately 70 °C (10 min), the dilution end-point is approximately 10(-4) and viral infectivity is lost after a few days of exposure to 20 °C. Viral infectivity can be retained in freeze-dried tissues and in the form of virions purified using 5 mm sodium borate, 0.5 mm ethylenediaminetetraacetic acid and 50% glycerol (pH 9.0) at -20 °C. CMV particles are isometric, approximately 28-30 nm in diameter and are composed of 180 capsid subunits arranged in pentamer-hexamer clusters with T= 3 symmetry. The sedimentation coefficient (s(20) ,(w) ) is c. 98 S and the particle weight is (5.8-6.7) × 10(6) Da. The virions contain 18% RNA. The RNA-protein interactions that stabilize the CMV virions are readily disrupted by sodium dodecylsulphate or neutral chloride salts. GENOMIC PROPERTIES: The genomic RNAs are single-stranded messenger sense RNAs with 5' cap and 3' tRNA-like structures containing at least five open reading frames. The viral RNA consists of three genomic RNAs, RNA 1 (c. 3.3 kb), RNA 2 (c. 3.0 kb) and RNA 3 (c. 2.2 kb), and two subgenomic RNAs, RNA 4 (c. 1.0 kb) and RNA 4A (c. 0.7 kb). The 3' untranslated regions are conserved across all viral RNAs. CMV is often accompanied by satellite, noncoding, small, linear RNA that is nonhomologous to the helper CMV.
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Affiliation(s)
- Tomofumi Mochizuki
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka, Japan.
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Abstract
Cucumber mosaic virus (CMV) is an important virus because of its agricultural impact in the Mediterranean Basin and worldwide, and also as a model for understanding plant-virus interactions. This review focuses on those areas where most progress has been made over the past decade in our understanding of CMV. Clearly, a deep understanding of the role of the recently described CMV 2b gene in suppression of host RNA silencing and viral virulence is the most important discovery. These findings have had an impact well beyond the virus itself, as the 2b gene is an important tool in the studies of eukaryotic gene regulation. Protein 2b was shown to be involved in most of the steps of the virus cycle and to interfere with several basal host defenses. Progress has also been made concerning the mechanisms of virus replication and movement. However, only a few host proteins that interact with viral proteins have been identified, making this an area of research where major efforts are still needed. Another area where major advances have been made is CMV population genetics, where contrasting results were obtained. On the one hand, CMV was shown to be prone to recombination and to show high genetic diversity based on sequence data of different isolates. On the other hand, populations did not exhibit high genetic variability either within plants, or even in a field and the nearby wild plants. The situation was partially clarified with the finding that severe bottlenecks occur during both virus movement within a plant and transmission between plants. Finally, novel studies were undertaken to elucidate mechanisms leading to selection in virus population, according to the host or its environment, opening a new research area in plant-virus coevolution.
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