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Assessment of the RNA Silencing Suppressor Activity of Protein P0 of Pepper Vein Yellows Virus 5: Uncovering Natural Variability, Relevant Motifs and Underlying Mechanism. BIOLOGY 2022; 11:biology11121801. [PMID: 36552310 PMCID: PMC9775047 DOI: 10.3390/biology11121801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 12/02/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022]
Abstract
Pepper vein yellows virus 5 (PeVYV-5) belongs to a group of emerging poleroviruses (family Solemoviridae) which pose a risk to pepper cultivation worldwide. Since its first detection in Spain in 2013 and the determination of the complete genome sequence of an isolate in 2018, little is known on the presence, genomic variation and molecular properties of this pathogen. As other members of genus Polerovirus, PeVYV-5 encodes a P0 protein that was predicted to act as viral suppressor of RNA silencing (VSR), one of the major antiviral defense mechanisms in plants. The results of the present work have indicated that PeVYV-5 P0 is a potent VSR, which is able to induce the degradation of Argonaute (AGO) endonucleases, the main effectors of RNA silencing. New viral isolates have been identified in samples collected in 2020-2021 and sequencing of their P0 gene has revealed limited heterogeneity, suggesting that the protein is under negative selection. Analysis of natural and engineered P0 variants has pinpointed distinct protein motifs as critical for the VSR role. Moreover, a positive correlation between the VSR activity of the protein and its capability to promote AGO degradation could be established, supporting that such activity essentially relies on the clearance of core components of the RNA silencing machinery.
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Wu H, Liu M, Kang B, Liu L, Hong N, Peng B, Gu Q. AC5 protein encoded by squash leaf curl China virus is an RNA silencing suppressor and a virulence determinant. Front Microbiol 2022; 13:980147. [PMID: 36060769 PMCID: PMC9437540 DOI: 10.3389/fmicb.2022.980147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/05/2022] [Indexed: 11/26/2022] Open
Abstract
Squash leaf curl China virus (SLCCNV) is a bipartite Begomovirus. The function of the protein AC5, which is encoded by SLCCNV, is unknown. Here, we confirmed that the 172-amino acids (aa) long AC5 protein of SLCCNV could suppress single-stranded RNA but not double-stranded RNA-induced post-transcriptional gene silencing (PTGS). Furthermore, we determined that the C-terminal domain (96–172 aa) of the AC5 protein was responsible for RNA silencing suppressor (RSS) activity via deletion mutant analysis. The AC5 protein can reverse GFP silencing and inhibit systemic silencing of GFP by interfering with the systemic spread of the GFP silencing signal. The SLCCNV AC5 protein was localized to both the nucleus and cytoplasm of Nicotiana benthamiana cells. Furthermore, deletion analysis showed that the putative nuclear localization signal (NLS, 102–155 aa) was crucial for the RNA silencing suppression activity of AC5. In addition, the AC5 protein elicited a hypersensitive response and enhanced potoao virus X (PVX) RNA accumulation in infected N. benthamiana plants. Using the infectious clones of the SLCCNV and SLCCNV-AC5 null mutants, mutational analysis confirmed that knockout of the AC5 gene abolished SLCCNV-induced leaf curl symptoms, showing SLCCNV AC5 is also a virulence determinant.
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Affiliation(s)
- Huijie Wu
- Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, China
| | - Mei Liu
- Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, China
| | - Baoshan Kang
- Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, China
| | - Liming Liu
- Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, China
| | - Ni Hong
- College of Plant Science and Technology, Huazhong Agricultural University/Key Lab of Plant Pathology of Hubei Province, Wuhan, China
| | - Bin Peng
- Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, China
- Bin Peng,
| | - Qinsheng Gu
- Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, China
- *Correspondence: Qinsheng Gu,
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Li Q, Zhang Y, Lu W, Han X, Yang L, Shi Y, Li H, Chen L, Liu Y, Yang X, Shi Y. Identification and characterization of a new geminivirus from soybean plants and determination of V2 as a pathogenicity factor and silencing suppressor. BMC PLANT BIOLOGY 2022; 22:362. [PMID: 35869422 PMCID: PMC9308217 DOI: 10.1186/s12870-022-03745-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Soybean is one of the four major crops in China. The occurrence of viruses in soybean causes significant economic losses. RESULTS In this study, the soybean leaves from stay-green plants showing crinkle were collected for metatranscriptomic sequencing. A novel geminivirus, tentatively named soybean geminivirus A (SGVA), was identified in soybean stay-green plants. Sequence analysis of the full-length SGVA genome revealed a genome of 2762 nucleotides that contain six open reading frames. Phylogenetic analyses revealed that SGVA was located adjacent to the clade of begomoviruses in both the full genome-based and C1-based phylogenetic tree, while in the CP-based phylogenetic tree, SGVA was located adjacent to the clade of becurtoviruses. SGVA was proposed as a new recombinant geminivirus. Agroinfectious clone of SGVA was constructed. Typical systemic symptoms of curly leaves were observed at 11 dpi in Nicotiana benthamiana plants and severe dwarfism was observed after 3 weeks post inoculation. Expression of the SGVA encoded V2 and C1 proteins through a potato virus X (PVX) vector caused severe symptoms in N. benthamiana. The V2 protein inhibited local RNA silencing in co-infiltration assays in GFP transgenic 16C N. benthamiana plants. Further study revealed mild symptoms in N. benthamiana plants inoculated with SGVA-ZZ V2-STOP and SGVA-ZZ V2-3738AA mutants. Both the relative viral DNA and CP protein accumulation levels significantly decreased when compared with SGVA-inoculated plants. CONCLUSIONS This work identified a new geminivirus in soybean stay-green plants and determined V2 as a pathogenicity factor and silencing suppressor.
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Affiliation(s)
- Qinglun Li
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Yuyang Zhang
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Weiguo Lu
- Institute of Crops Molecular Breeding, Henan Academy of Agricultural Sciences/ National Centre for Plant Breeding, Zhengzhou, 450002, China
| | - Xiaoyu Han
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Lingling Yang
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Yajuan Shi
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Honglian Li
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Linlin Chen
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China
| | - Yiqing Liu
- Guangdong Baiyun University, Guangzhou, 510550, China
| | - Xue Yang
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China.
| | - Yan Shi
- College of Plant Protection, Henan Agricultural University, Zhengzhou, 450002, China.
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