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Genetic diversity and silencing suppression effects of Rice yellow mottle virus and the P1 protein.

Siré C, Bangratz-Reyser M, Fargette D, Brugidou C - Virol. J. (2008)

Bottom Line: However, we found considerable diversity in their ability to suppress silencing which was not linked to RYMV phylogeny, or pathogenicity.At the level of the silencing suppressor P1 alone, we found similar results to those previously found at the virion level.These results are potentially important for understanding virus-host interactions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut de Recherche pour le Développement (IRD), UMR LGDP, 34394 Montpellier Cedex 5, France. sire.christelle@gmail.com

ABSTRACT

Background: PTGS (post-transcriptional gene silencing) is used to counter pathogenic invasions, particularly viruses. In return, many plant viruses produce proteins which suppress silencing directed against their RNA. The diversity of silencing suppression at the species level in natural hosts is unknown.

Results: We investigated the functional diversity of silencing suppression among isolates of the African RYMV (Rice yellow mottle virus) in rice. The RYMV-P1 protein is responsible for cell-to-cell movement and is a silencing suppressor. Transgenic gus-silencing rice lines were used to investigate intra-specific and serogroup silencing suppression diversity at two different levels: that of the virion and the P1 silencing suppressor protein. Our data provide evidence that silencing suppression is a universal phenomenon for RYMV species. However, we found considerable diversity in their ability to suppress silencing which was not linked to RYMV phylogeny, or pathogenicity. At the level of the silencing suppressor P1 alone, we found similar results to those previously found at the virion level. In addition, we showed that cell-to-cell movement of P1 was crucial for the efficiency of silencing suppression. Mutagenesis of P1 demonstrated a strong link between some amino acids and silencing suppression features with, one on the hand, the conserved amino acids C95 and C64 involved in cell-to-cell movement and the strength of suppression, respectively, and on the other hand, the non conserved F88 was involved in the strength of silencing suppression.

Conclusion: We demonstrated that intra-species diversity of silencing suppression is highly variable and by mutagenesis of P1 we established the first link between silencing suppression and genetic diversity. These results are potentially important for understanding virus-host interactions.

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Related in: MedlinePlus

Effect of the P1 protein from different RYMV isolates on silencing suppression in rice. Transgenic L10 leaves were analysed after different treatments; non-biolistic delivery (ND), buffer delivery (BD), biolistic delivery with a empty 35S vector (35S), or vectors containing different sP1 from RYMV isolates representative of the viral phylogeny (CI63, Mg1, Tz8, Tz3, BF1). Non transgenic Tai and transgenic L4 served as controls. (A) Photographs correspond to GUS staining at 2 dpd of inoculated leaves. (B) Quantitative effect of different P1 at 2 dpd on gus-specific siRNA with Northern blot experiments. EtBr staining of rRNA served as a loading control.
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Figure 5: Effect of the P1 protein from different RYMV isolates on silencing suppression in rice. Transgenic L10 leaves were analysed after different treatments; non-biolistic delivery (ND), buffer delivery (BD), biolistic delivery with a empty 35S vector (35S), or vectors containing different sP1 from RYMV isolates representative of the viral phylogeny (CI63, Mg1, Tz8, Tz3, BF1). Non transgenic Tai and transgenic L4 served as controls. (A) Photographs correspond to GUS staining at 2 dpd of inoculated leaves. (B) Quantitative effect of different P1 at 2 dpd on gus-specific siRNA with Northern blot experiments. EtBr staining of rRNA served as a loading control.

Mentions: We demonstrated a lack of effect due to biolistic delivery and the expression vector by using empty 35S (Figure 5A and 5B lane 5). At 1 day post delivery (dpd), we revealed the reversion of GUS activity, except for sTz8 for which GUS activity was only observed at 2 dpd (Figure 5A). We thus demonstrated for the first time in a natural host, that all P1s from different RYMV isolates were silencing suppressors. In addition, we observed the reversion of GUS activity over the entire leaf, even where the P1 protein had not been delivered, suggesting strong movement of this protein (Figure 5A).


Genetic diversity and silencing suppression effects of Rice yellow mottle virus and the P1 protein.

Siré C, Bangratz-Reyser M, Fargette D, Brugidou C - Virol. J. (2008)

Effect of the P1 protein from different RYMV isolates on silencing suppression in rice. Transgenic L10 leaves were analysed after different treatments; non-biolistic delivery (ND), buffer delivery (BD), biolistic delivery with a empty 35S vector (35S), or vectors containing different sP1 from RYMV isolates representative of the viral phylogeny (CI63, Mg1, Tz8, Tz3, BF1). Non transgenic Tai and transgenic L4 served as controls. (A) Photographs correspond to GUS staining at 2 dpd of inoculated leaves. (B) Quantitative effect of different P1 at 2 dpd on gus-specific siRNA with Northern blot experiments. EtBr staining of rRNA served as a loading control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2390521&req=5

Figure 5: Effect of the P1 protein from different RYMV isolates on silencing suppression in rice. Transgenic L10 leaves were analysed after different treatments; non-biolistic delivery (ND), buffer delivery (BD), biolistic delivery with a empty 35S vector (35S), or vectors containing different sP1 from RYMV isolates representative of the viral phylogeny (CI63, Mg1, Tz8, Tz3, BF1). Non transgenic Tai and transgenic L4 served as controls. (A) Photographs correspond to GUS staining at 2 dpd of inoculated leaves. (B) Quantitative effect of different P1 at 2 dpd on gus-specific siRNA with Northern blot experiments. EtBr staining of rRNA served as a loading control.
Mentions: We demonstrated a lack of effect due to biolistic delivery and the expression vector by using empty 35S (Figure 5A and 5B lane 5). At 1 day post delivery (dpd), we revealed the reversion of GUS activity, except for sTz8 for which GUS activity was only observed at 2 dpd (Figure 5A). We thus demonstrated for the first time in a natural host, that all P1s from different RYMV isolates were silencing suppressors. In addition, we observed the reversion of GUS activity over the entire leaf, even where the P1 protein had not been delivered, suggesting strong movement of this protein (Figure 5A).

Bottom Line: However, we found considerable diversity in their ability to suppress silencing which was not linked to RYMV phylogeny, or pathogenicity.At the level of the silencing suppressor P1 alone, we found similar results to those previously found at the virion level.These results are potentially important for understanding virus-host interactions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut de Recherche pour le Développement (IRD), UMR LGDP, 34394 Montpellier Cedex 5, France. sire.christelle@gmail.com

ABSTRACT

Background: PTGS (post-transcriptional gene silencing) is used to counter pathogenic invasions, particularly viruses. In return, many plant viruses produce proteins which suppress silencing directed against their RNA. The diversity of silencing suppression at the species level in natural hosts is unknown.

Results: We investigated the functional diversity of silencing suppression among isolates of the African RYMV (Rice yellow mottle virus) in rice. The RYMV-P1 protein is responsible for cell-to-cell movement and is a silencing suppressor. Transgenic gus-silencing rice lines were used to investigate intra-specific and serogroup silencing suppression diversity at two different levels: that of the virion and the P1 silencing suppressor protein. Our data provide evidence that silencing suppression is a universal phenomenon for RYMV species. However, we found considerable diversity in their ability to suppress silencing which was not linked to RYMV phylogeny, or pathogenicity. At the level of the silencing suppressor P1 alone, we found similar results to those previously found at the virion level. In addition, we showed that cell-to-cell movement of P1 was crucial for the efficiency of silencing suppression. Mutagenesis of P1 demonstrated a strong link between some amino acids and silencing suppression features with, one on the hand, the conserved amino acids C95 and C64 involved in cell-to-cell movement and the strength of suppression, respectively, and on the other hand, the non conserved F88 was involved in the strength of silencing suppression.

Conclusion: We demonstrated that intra-species diversity of silencing suppression is highly variable and by mutagenesis of P1 we established the first link between silencing suppression and genetic diversity. These results are potentially important for understanding virus-host interactions.

Show MeSH
Related in: MedlinePlus