Citrus tristeza virus: Host RNA Silencing and Virus Counteraction

Ruiz-Ruiz, Susana; Navarro, Beatriz; Peña, Leandro; Navarro, Luís; Moreno, Pedro; Serio, Francesco Di; Flores, Ricardo

doi:10.1007/978-1-4939-9558-5_14

Cited by 8 publications

(3 citation statements)

References 74 publications

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“…Remarkably, we found strong evidence of argonaute proteins AGO1 and AGO4 being relevant targets of p20 since they appeared in AP-MS and BiFC assays. This agrees with recent results suggesting that CTV suppressors act once the siRNAs are generated [ 50 ]. Notably, the functionally-related suppressor 2b of Cucumber mosaic virus has been shown to target AGO1 and disrupt its cleavage ability [ 51 ].…”

Section: Discussionsupporting

confidence: 93%

Molecular signatures of silencing suppression degeneracy from a complex RNA virus

et al. 2021

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As genomic architectures become more complex, they begin to accumulate degenerate and redundant elements. However, analyses of the molecular mechanisms underlying these genetic architecture features remain scarce, especially in compact but sufficiently complex genomes. In the present study, we followed a proteomic approach together with a computational network analysis to reveal molecular signatures of protein function degeneracy from a plant virus (as virus-host protein-protein interactions). We employed affinity purification coupled to mass spectrometry to detect several host factors interacting with two proteins of Citrus tristeza virus (p20 and p25) that are known to function as RNA silencing suppressors, using an experimental system of transient expression in a model plant. The study was expanded by considering two different isolates of the virus, and some key interactions were confirmed by bimolecular fluorescence complementation assays. We found that p20 and p25 target a common set of plant proteins including chloroplastic proteins and translation factors. Moreover, we noted that even specific targets of each viral protein overlap in function. Notably, we identified argonaute proteins (key players in RNA silencing) as reliable targets of p20. Furthermore, we found that these viral proteins preferentially do not target hubs in the host protein interactome, but elements that can transfer information by bridging different parts of the interactome. Overall, our results demonstrate that two distinct proteins encoded in the same viral genome that overlap in function also overlap in their interactions with the cell proteome, thereby highlighting an overlooked connection from a degenerate viral system.

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Section: Discussionsupporting

confidence: 93%

Molecular signatures of silencing suppression degeneracy from a complex RNA virus

et al. 2021

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“…The P20 protein has a key role in the suppression of RNA silencing [ 22 ] and might block the loading of CTV sRNAs into the RNA silencing complex or interfere with it through alternative mechanisms [ 23 ]. The CPm protein was the third highest-expressed gene with functions in virus movement and assembly.…”

Section: Resultsmentioning

confidence: 99%

Complete genome sequencing and characterization of a potential new genotype of Citrus tristeza virus in Iran

et al. 2023

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Citrus tristeza virus (CTV) is one of the economically destructive viruses affecting citrus trees worldwide, causing significant losses in fruit production. Comparative genomic studies have shown genetic diversity in various regions of the genome of CTV isolates, which has classified the virus into several genotypes. In recent years, some orange citrumelo-tolerant rootstocks showed yellowing, decline, and vein clearing in northern Iran (Mazandaran province, Sari). We confirmed the presence of CTV in the symptomatic trees by reverse transcription PCR (RT-PCR). The complete genome of a Sari isolate of CTV (Sari isolate) was sequenced using next-generation sequencing (NGS) technology. In addition, phylogenetic analysis, differential gene expression of the virus and identification of its variants in a population were studied. We obtained the final contigs of the virus (nt) and annotated all genomes to viral ORFs, untranslated regions (UTRs), intergenic regions, and 5’ and 3’ ends of the genome. Phylogenetic analysis of the Sari isolate and other genotypes of CTV showed that the Sari isolates were placed in a distinct cluster without a sister group. Based on the number of specific transcripts (TPM) in CTV RNA -Seq, P13 was the most highly expressed gene related to the host range of the virus and its systemic infection. The ORFs of the polyprotein, P33, and P18 showed variation in a single population of the sari isolate. The CTV has a potential for variation in a population in a host, and these variations may contribute to the best fit of the CTV in different situations. In Iran, whole genome sequencing of the CTV was performed for the first time, and we gained new insights into CTV variation in a population.

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“…The nucleotide variation of serine to asparagine at position 54 is confirmed in the additional isolates that were fully or partially sequenced in this study ( Table 5 ). The substitution of Ser54 with Asn54 in the 50–54 region was reported to cause substantial changes in the phenotypic expression in specific hosts [ 48 , 49 ]. It could be that the G-to-A mutation of p23 abolishes the CTV SY reaction in SO plants, and the ‘ATC’ mutation of p33 allows the A-possessing mutant to spread and become dominant in an SY-reacting SO hosts.…”

Section: Discussionmentioning

confidence: 99%

Minor Variants of Orf1a, p33, and p23 Genes of VT Strain Citrus Tristeza Virus Isolates Show Symptomless Reactions on Sour Orange and Prevent Superinfection of Severe VT Isolates

Licciardello,

Scuderi,

Russo

et al. 2023

Viruses

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The control of tristeza quick decline (QD) of citrus is based on the use of rootstocks that are tolerant or resistant to the Citrus tristeza virus (CTV), but some of them show bio-agronomic limits. The application of cross-protection (CP) has been insufficiently explored. The present study examined the possibility of QD control by cross-protection (CP) following reports showing the dependence of the CP strategy on the close genetic relationships between the protective and challenging CTV isolates. Taking advantage of deep sequencing technologies, we located six naturally infected trees harboring no-seedling yellow (no-SY) and no QD decline (mild) VT isolates and used these for challenge inoculation with three QD VT isolates. Symptom monitoring showed that all six Sicilian mild no-SY isolates, based on their genomic relatedness and mild symptoms reactions, provide effective protection against the three severe local VT isolates. The differences between the six mild and three severe isolates were confined to just a few nucleotide variations conserved in eight positions of three CTV genes (p23, p33, and Orf1a). These results confirm that the superinfection exclusion (SIE mechanism) depends on close genetic relatedness between the protective and challenging severe VT strain isolates. Ten years of investigation suggest that CP could turn into an efficient strategy to contain CTV QD infections of sweet orange trees on SO rootstock.

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Citrus tristeza virus: Host RNA Silencing and Virus Counteraction

Cited by 8 publications

References 74 publications

Molecular signatures of silencing suppression degeneracy from a complex RNA virus

Molecular signatures of silencing suppression degeneracy from a complex RNA virus

Complete genome sequencing and characterization of a potential new genotype of Citrus tristeza virus in Iran

Minor Variants of Orf1a, p33, and p23 Genes of VT Strain Citrus Tristeza Virus Isolates Show Symptomless Reactions on Sour Orange and Prevent Superinfection of Severe VT Isolates

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