scholarly journals The 2b protein of cucumber mosaic virus is essential for viral infection of the shoot apical meristem and for efficient invasion of leaf primordia in infected tobacco plants

2009 ◽  
Vol 90 (12) ◽  
pp. 3015-3021 ◽  
Author(s):  
Anurag Sunpapao ◽  
Takashi Nakai ◽  
Fang Dong ◽  
Tomofumi Mochizuki ◽  
Satoshi T. Ohki
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Shoot Apical Meristem ◽  
Rna Silencing ◽  
Apical Meristem ◽  
Leaf Primordia ◽  
Shoot Meristem ◽  
Tobacco Plants ◽  
2B Protein ◽  
Infected Tobacco

It has been reported previously that a 2b protein-defective mutant of the cucumber mosaic virus (CMV) Pepo strain (Δ2b) induces only mild symptoms in systemically infected tobacco plants. To clarify further the role of the 2b protein as an RNA silencing suppressor in mosaic symptom expression during CMV infection, this study monitored the sequential distribution of Δ2b in the shoot meristem and leaf primordia (LP) of inoculated tobacco. Time-course histochemical observations revealed that Δ2b was distributed in the shoot meristem at 7 days post-inoculation (p.i.), but could not invade shoot apical meristem (SAM) and quickly disappeared from the shoot meristem, whereas wild-type (Pepo) transiently appeared in SAM from 4 to 10 days p.i. In LP, Δ2b signals were detected only at 14 and 21 days p.i., whereas dense Pepo signals were observed in LP from 4 to 18 days p.i. Northern blot analysis showed that small interfering RNA (siRNA) derived from Δ2b RNA accumulated earlier in the shoot meristem and LP than that of Pepo. However, a similar amount of siRNA was detected in both Pepo- and Δ2b-infected plants at late time points. Tissue printing analysis of the inoculated leaves indicated that the areas infected by Pepo increased faster than those infected by Δ2b, whereas accumulation of Δ2b in protoplasts was similar to that of Pepo. These findings suggest that the 2b protein of the CMV Pepo strain determines virulence by facilitating the distribution of CMV in the shoot meristem and LP via prevention of RNA silencing and/or acceleration of cell-to-cell movement.

scholarly journals Symptom induction and RNA silencing suppression by the cucumber mosaic virus 2b protein

2010 ◽  
Vol 5 (6) ◽  
pp. 705-708 ◽  
Author(s):  
Mathew G. Lewsey ◽  
Inmaculada González ◽  
Natalia O. Kalinina ◽  
Peter Palukaitis ◽  
Tomas Canto ◽  
...  
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Rna Silencing ◽  
2B Protein ◽  
Silencing Suppression

scholarly journals The Weak Small RNA-Binding Activity of the 2b Proteins of Subgroup II Cucumber Mosaic Virus Strains Is Insufficient for RNA Silencing Suppression

2021 ◽  
Vol 12 ◽  
Author(s):  
Yingying Gao ◽  
Jinrui Yang ◽  
Xiaobei Zhang ◽  
Aizhong Chen ◽  
Zhouhang Gu ◽  
...  
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Rna Silencing ◽  
Rna Binding ◽  
Nuclear Accumulation ◽  
Nuclear Localization Sequence ◽  
Binding Ability ◽  
Suppressor Activity ◽  
Subgroup Ii ◽  
2B Protein

The 2b proteins encoded by cucumber mosaic virus (CMV) subgroup I strains suppress RNA silencing primarily by competitively binding small RNAs (sRNAs) in the host cell cytoplasm. Interestingly, 2b proteins encoded by CMV subgroup II strains accumulate predominantly in nuclei. Here we determined that whereas the 2b protein (Fny2b) of subgroup IA strain Fny-CMV is highly effective in suppressing both sense RNA-induced and inverted repeat-induced posttranscriptional gene silencing, the 2b protein (LS2b) of the subgroup II strain LS-CMV was not as effective. Reducing nuclear accumulation of LS2b by mutating a residue in its nuclear localization sequence had no effect on RNA silencing suppressor activity, while attenuated viral symptoms. Electrophoretic mobility shift assays showed that the sRNA binding of LS2b was weaker and more selective than that of Fny2b. The domain determining the differential sRNA-binding ability was delimited to the putative helix α1 region. Moreover, LS2b mutants that completely lost suppressor activity still retained their weak sRNA-binding ability, suggesting that sRNA binding is not sufficient for LS2b to suppress RNA silencing. Considering the subgroup I strain-encoded 2b proteins that require sRNA-binding ability for the suppression of RNA silencing, we suggest that in addition to binding sRNA, the 2b proteins of subgroup II CMV strains would require extra biological activities to achieve RNA silencing inhibition.

Subcellular distribution analysis of the cucumber mosaic virus 2b protein

Microbiology ◽  
2000 ◽  
Vol 81 (1) ◽  
pp. 219-226 ◽  
Author(s):  
Carl N. Mayers ◽  
Peter Palukaitis ◽  
John P. Carr
Keyword(s):  
Host Cell ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Leaf Tissue ◽  
Subcellular Fractionation ◽  
Distribution Analysis ◽  
Virus Induced Gene Silencing ◽  
Pellet Fraction ◽  
2B Protein ◽  
Infected Tobacco

The cucumoviral 2b protein is a viral counterdefence factor that interferes with the establishment of virus-induced gene silencing in plants. Synthetic peptides were used to generate an antibody to the 2b protein encoded by the Fny strain of cucumber mosaic virus (Fny-CMV). This polyclonal antibody was able to recognize the Fny-CMV 2b protein in a 10000 g pellet fraction of infected tobacco. No protein of equivalent size was detected in mock-inoculated or tobacco mosaic virus-infected samples. This represents the first demonstration of 2b protein expression by a subgroup I strain of CMV. Subcellular fractionation experiments on CMV-infected tobacco leaf tissue showed that the Fny-CMV 2b protein accumulated within a fraction that sedimented at forces of less than 5000 g and that the 2b protein was solubilized only by treatment with urea or SDS. These results suggested that the 2b protein associates either with the nucleus or cytoskeleton of the host cell. Further analysis showed that the 2b protein was enriched in a fraction that sedimented through a 2·2 M sucrose cushion. This fraction was also enriched in histones, suggesting that the CMV 2b protein associates preferentially with the host cell nucleus.

Effects of the 2b Protein of Cucumber mosaic virus Subgroup IB Strain IA on Different Transgene-Induced RNA Silencing Pathways

2017 ◽  
Vol 35 (2) ◽  
pp. 265-272 ◽  
Author(s):  
Mayuko Koizumi ◽  
Yumi Shimotori ◽  
Yuta Saeki ◽  
Sayaka Hirai ◽  
Shin-ichiro Oka ◽  
...  
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Rna Silencing ◽  
2B Protein ◽  
Silencing Pathways

scholarly journals Elevated Carbon Dioxide Levels Decreases Cucumber Mosaic Virus Accumulation in Correlation with Greater Accumulation of rgs-CaM, an Inhibitor of a Viral Suppressor of RNAi

Plants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 59
Author(s):  
Huijuan Guo ◽  
Panpan Ge ◽  
Jiahui Tong ◽  
Yanjing Zhang ◽  
Xinhong Peng ◽  
...  
Keyword(s):  
Climate Change ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Elevated Co2 ◽  
Plant Viruses ◽  
Plant Diseases ◽  
Tobacco Plants ◽  
Viral Suppressor ◽  
Co2 Levels ◽  
2B Protein

Plant viruses cause a range of plant diseases symptoms that are often responsible for significant crop production losses and the severity and spread of the symptoms may be affected by climate change. While the increase in anthropogenic activities has caused a critical problem of increased CO2 levels in the atmosphere, these elevated CO2 levels have been reported to reduce virus disease severity in some plant species. In such instances, it is not clear if the plant defense mechanisms are being enhanced or virus-mediated mechanisms to overcome plant resistance are being defeated. Additionally, a few studies have been attempted in this area to determine if reduced disease is the norm or the exception under enhanced CO2 levels. In the present study, the effects of elevated CO2 levels (750 ppm vs. 390 ppm) on RNAi-mediated resistance of Nicotiana tabacum against the cucumber mosaic virus (CMV), and the activity of viral suppressor of RNAi (VSR) 2b protein of CMV were evaluated. On the one hand, our results showed that elevated CO2 decreased the transcription of dicer-like protein 2 (DCL2), DCL4, and argonaut 1 (AGO1) genes with functions related to RNAi-mediated resistance when infected by CMV, which is contradictory with the decreased CMV copy numbers under elevated CO2. On the other hand, we found that elevated CO2 increased the calcium concentration and expression of the calcium-binding protein rgs-CaM in tobacco plants when infected by CMV, which directly weakened the function of 2b protein, the VSR of CMV, and therefore decreased the infection efficiency of the virus and suppressed the severity of CMV in tobacco plants under elevated CO2. This study provides molecular insights into the ecological implications underlying the development of prevention strategies against plant virus infection in the context of climate change.

Sign in / Sign up

Export Citation Format

Share Document