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Kang YC, Yeh SD, Chen TC. Leucine 127 of Cucurbit Chlorotic Yellows Virus P22 Is Crucial for Its RNA Silencing Suppression Activity and Pathogenicity. PHYTOPATHOLOGY 2024; 114:813-822. [PMID: 37913633 DOI: 10.1094/phyto-07-23-0227-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Plant viruses produce particular suppressors to antagonize the host defense response of RNA silencing to establish infection. Cucurbit chlorotic yellows virus (CCYV), a member of the genus Crinivirus of the family Closteroviridae, severely damages the production of economically essential cucurbits worldwide. Here, we used the attenuated zucchini yellow mosaic virus (ZYMV) vector ZAC to express individual coding sequences, including CP, CPm, P25, and P22, of a Taiwan CCYV isolate (CCYV-TW) to identify their possible roles as pathogenicity determinants. ZAC is an HC-Pro function mutant that lacks the ability of local lesion induction on Chenopodium quinoa leaves and induces mild mottling followed by recovery on its natural host zucchini squash plants. Only the recombinant expressing CCYV-TW P22 complemented the effect of ZAC HC-Pro dysfunction, causing more severe symptoms on zucchini squash plants and restoring lesion formation on C. quinoa leaves, with lesions forming faster than those generated by the wild-type ZYMV. This suggests that CCYV-TW P22 is a virulence enhancer. Sequence analysis of criniviral P22s revealed the presence of four conserved leucine residues (L10, L17, L84, and L127) and one conserved lysine residue (K185). The five P22 residues conserved among the CCYV isolates and the P22 orthologs of two other criniviruses were each substituted with alanine in CCYV-TW P22 to investigate its ability to suppress RNA silencing and pathogenicity. The results provide new insights into CCYV-P22, showing that the L127 residue of P22 is indispensable for maintaining its stability in RNA silencing suppression and essential for virulence enhancement.
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Affiliation(s)
- Ya-Chi Kang
- Department of Medical Laboratory Science and Biotechnology, Asia University, Wufeng, Taichung 41354, Taiwan
- Department of Plant Pathology, National Chung Hsing University, Taichung 40227, Taiwan
| | - Shyi-Dong Yeh
- Department of Plant Pathology, National Chung Hsing University, Taichung 40227, Taiwan
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan
| | - Tsung-Chi Chen
- Department of Medical Laboratory Science and Biotechnology, Asia University, Wufeng, Taichung 41354, Taiwan
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Ye X, Ding D, Chen Y, Liu C, Li Z, Lou B, Zhou Y. Identification of RNA silencing suppressor encoded by citrus chlorotic dwarf-associated virus. Front Microbiol 2024; 15:1328289. [PMID: 38333582 PMCID: PMC10850569 DOI: 10.3389/fmicb.2024.1328289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 01/04/2024] [Indexed: 02/10/2024] Open
Abstract
Introduction Citrus chlorotic dwarf-associated virus (CCDaV) is an economically important citrus virus associated with leaf curling, deformation, and chlorosis found in China. Plants have evolved RNA silencing to defend against viral infections; however, the mechanism by which CCDaV suppresses RNA silencing in citrus remains unknown. Methods Six proteins encoded by CCDaV were ectopically expressed in Nicotiana benthamiana 16c using the pCHF3 vector to identify RNA-silencing suppression activities. Results V2 protein encoded by CCDaV suppressed local RNA silencing and systemic RNA silencing triggered by GFP RNA, but did not impede short-distance movement of the RNA silencing signal in N. benthamiana 16c. GFP fluorescence observations showed that the ability of V2 protein to suppress RNA silencing was weaker than tomato bushy stunt virus P19. Deletion analysis showed that the putative nuclear localization signal (NLS, 25-54 aa) was involved in the RNA silencing suppression activity of V2 protein. Furthermore, V2 protein cannot block dsRNA-triggered RNA silencing. The subcellular localization assay suggested that V2 protein was localized to nucleus of N. benthamiana. Conclusion Overall, the results of this study demonstrate that CCDaV-V2 acts as an activity of silencing suppression. This is the first reported RNA-silencing suppressor encoded by Citlodavirus and will be valuable in revealing the molecular mechanism of CCDaV infection.
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Affiliation(s)
- Xiao Ye
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City/Citrus Research Institute, Southwest University, Chongqing, China
| | - Dongdong Ding
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City/Citrus Research Institute, Southwest University, Chongqing, China
| | - Yuan Chen
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City/Citrus Research Institute, Southwest University, Chongqing, China
| | - Chuang Liu
- Lemon Industry Development Center, Anyue, Sichuan, China
| | - Zhongan Li
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City/Citrus Research Institute, Southwest University, Chongqing, China
| | - Binghai Lou
- Guangxi Citrus Breeding and Cultivation Research Center of Engineering Technology/Guangxi Academy of Specialty Crops, Guilin, Guangxi, China
| | - Yan Zhou
- Integrative Science Center of Germplasm Creation in Western China (CHONGQING) Science City/Citrus Research Institute, Southwest University, Chongqing, China
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Yang X, Wei Y, Shi Y, Han X, Chen S, Yang L, Li H, Sun B, Shi Y. Cucumber Ribosomal Protein CsRPS21 Interacts With P22 Protein of Cucurbit Chlorotic Yellows Virus. Front Microbiol 2021; 12:654697. [PMID: 33995313 PMCID: PMC8116660 DOI: 10.3389/fmicb.2021.654697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 04/07/2021] [Indexed: 11/24/2022] Open
Abstract
Cucurbit chlorotic yellows virus (CCYV) is a cucurbit-infecting crinivirus. RNA silencing can be initiated as a plant defense against viruses. Viruses encode various RNA silencing suppressors to counteract antiviral silencing. P22 protein encoded by RNA1 of CCYV is a silencing suppressor, but its mechanism of action remains unclear. In this study, the cucumber ribosomal-like protein CsRPS21 was found to interact with P22 protein in vitro and in vivo. A conserved CsRPS21 domain was indispensable for its nuclear localization and interaction with P22. Transient expression of CsRPS21 in Nicotiana benthamiana leaves interfered with P22 accumulation and inhibited P22 silencing suppressor activity. CsRPS21 expression in N. benthamiana protoplasts inhibited CCYV accumulation. Increasing numbers of ribosomal proteins are being found to be involved in viral infections of plants. We identified a P22-interacting ribosomal protein, CsRPS21, and uncovered its role in early viral replication and silencing suppressor activity. Our study increases knowledge of the function of ribosomal proteins during viral infection.
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Affiliation(s)
- Xue Yang
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Ying Wei
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Yajuan Shi
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Xiaoyu Han
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Siyu Chen
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Lingling Yang
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Honglian Li
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Bingjian Sun
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Yan Shi
- College of Plant Protection, Henan Agricultural University, Zhengzhou, China
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Domingo-Calap ML, Chase O, Estapé M, Moreno AB, López-Moya JJ. The P1 Protein of Watermelon mosaic virus Compromises the Activity as RNA Silencing Suppressor of the P25 Protein of Cucurbit yellow stunting disorder virus. Front Microbiol 2021; 12:645530. [PMID: 33828542 PMCID: PMC8019732 DOI: 10.3389/fmicb.2021.645530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/02/2021] [Indexed: 11/17/2022] Open
Abstract
Mixed viral infections in plants involving a potyvirus and other unrelated virus often result in synergistic effects, with significant increases in accumulation of the non-potyvirus partner, as in the case of melon plants infected by the potyvirus Watermelon mosaic virus (WMV) and the crinivirus Cucurbit yellow stunting disorder virus (CYSDV). To further explore the synergistic interaction between these two viruses, the activity of RNA silencing suppressors (RSSs) was addressed in transiently co-expressed combinations of heterologous viral products in Nicotiana benthamiana leaves. While the strong RSS activity of WMV Helper Component Proteinase (HCPro) was unaltered, including no evident additive effects observed when co-expressed with the weaker CYSDV P25, an unexpected negative effect of WMV P1 was found on the RSS activity of P25. Analysis of protein expression during the assays showed that the amount of P25 was not reduced when co-expressed with P1. The detrimental action of P1 on the activity of P25 was dose-dependent, and the subcellular localization of fluorescently labeled variants of P1 and P25 when transiently co-expressed showed coincidences both in nucleus and cytoplasm. Also, immunoprecipitation experiments showed interaction of tagged versions of the two proteins. This novel interaction, not previously described in other combinations of potyviruses and criniviruses, might play a role in modulating the complexities of the response to multiple viral infections in susceptible plants.
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Affiliation(s)
- Maria Luisa Domingo-Calap
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain.,Instituto Valencia de Investigaciones Agrarias, IVIA, Valencia, Spain
| | - Ornela Chase
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain
| | - Mariona Estapé
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain.,Universitair Medisch Centrum, UMC, Utrecht, Netherlands
| | - Ana Beatriz Moreno
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain
| | - Juan José López-Moya
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona, Spain.,Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
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Salavert F, Navarro JA, Owen CA, Khechmar S, Pallás V, Livieratos IC. Cucurbit chlorotic yellows virus p22 suppressor of RNA silencing binds single-, double-stranded long and short interfering RNA molecules in vitro. Virus Res 2020; 279:197887. [PMID: 32045630 DOI: 10.1016/j.virusres.2020.197887] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/29/2020] [Accepted: 01/29/2020] [Indexed: 10/25/2022]
Abstract
Cucurbit chlorotic yellows virus (CCYV) is a new member of the genus Crinivirus (family Closteroviridae) with a bi-partite genome. CCYV RNA 1-encoded p22 has recently been reported to be a weak local suppressor of RNA silencing for which an interaction with cucumber SKP1LB1 through an F-box-like motif was demonstrated to be essential. Using a bacterially expressed maltose-binding protein (MBP) fusion of CCYV p22 in electrophoretic mobility shift assays (EMSA), we have examined in vitro its ability to bind different RNA templates. Our experiments showed that CCYV p22 is able to bind to ss and ds long RNAs, in addition to ss and ds small interfering (si) RNA molecules. CCYV p22 deletion mutants (MBP_CCYV DEL1-4) were produced that covered the entire protein, with MBP_CCYV DEL2 corresponding to the F-box motif and its flanking sequences. None of these deletions abolished the capacity of CCYV p22 to bind ss- and dsRNA molecules. However, deletions affecting the C-terminal half of the protein resulted in decreased binding efficiency for either ss- or dsRNA molecules indicating that essential elements for these interactions are located in this region. Taken together, our data add to current knowledge of the mode of action of suppressors of RNA silencing encoded by genes sited at the 3'-terminus of crinivirus genomic RNA 1, and shed light on the involvement of CCYV p22 in the suppression of RNA silencing and/or in another role in the virus life cycle via RNA binding.
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Affiliation(s)
- Ferran Salavert
- Department of Sustainable Agriculture, Mediterranean Agronomic Institute of Chania, Alsylio Agrokepion, GR-73100, Chania, Crete, Greece
| | - José Antonio Navarro
- Instituto De Biología Molecular y Celular De Plantas, Universidad Politécnica De Valencia-CSIC, Av. De Los Naranjos s/n, 46022, Valencia, Spain
| | - Carolyn A Owen
- Department of Sustainable Agriculture, Mediterranean Agronomic Institute of Chania, Alsylio Agrokepion, GR-73100, Chania, Crete, Greece
| | - Souheyla Khechmar
- Department of Sustainable Agriculture, Mediterranean Agronomic Institute of Chania, Alsylio Agrokepion, GR-73100, Chania, Crete, Greece
| | - Vicente Pallás
- Instituto De Biología Molecular y Celular De Plantas, Universidad Politécnica De Valencia-CSIC, Av. De Los Naranjos s/n, 46022, Valencia, Spain
| | - Ioannis C Livieratos
- Department of Sustainable Agriculture, Mediterranean Agronomic Institute of Chania, Alsylio Agrokepion, GR-73100, Chania, Crete, Greece.
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