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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

ORF4 (CP)-based phylogenetic tree. Phylogenetic tree reconstructed from 179 partially sequenced isolates from the 15 countries where RYMV has been reported: Benin, Burkina Faso (BF), Chad, Ivory Coast (CI), Cameroon, Ghana, Guinea, Kenya, Madagascar (Mg), Mali, Niger, Nigeria (Ni), Sierra Leone, Tanzania (Tz) and Togo. The Kimura2 substitution model with estimates of the alpha parameter of the gamma shape was applied. The serotype of the isolates defined by reactions with a set of monoclonal antibodies in ELISA tests (47) is indicated (by vertical bars) at the right of the figure.
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Figure 2: ORF4 (CP)-based phylogenetic tree. Phylogenetic tree reconstructed from 179 partially sequenced isolates from the 15 countries where RYMV has been reported: Benin, Burkina Faso (BF), Chad, Ivory Coast (CI), Cameroon, Ghana, Guinea, Kenya, Madagascar (Mg), Mali, Niger, Nigeria (Ni), Sierra Leone, Tanzania (Tz) and Togo. The Kimura2 substitution model with estimates of the alpha parameter of the gamma shape was applied. The serotype of the isolates defined by reactions with a set of monoclonal antibodies in ELISA tests (47) is indicated (by vertical bars) at the right of the figure.

Mentions: We used 10 fully sequenced RYMV isolates belonging to different serogroups and representative of viral diversity in Africa (i.e. with 9.9% maximum diversity) [19,23], these were; BF1, CI63, CI4, Ni1, Ni2, Mg1, Tz3, Tz5, Tz8 and Tz11. There was a second set of 10 isolates belonging to serogroup 2, showing variable pathogenicity assessed through symptom intensity, but low sequence diversity (2%). These were; CI110, 111, 112, 113, 114, 115, 116, 121, 129, and 138 [27] (Figure 2). They were independently propagated in the susceptible cultivar O. sativa spp. indica cv. IR64.


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)

ORF4 (CP)-based phylogenetic tree. Phylogenetic tree reconstructed from 179 partially sequenced isolates from the 15 countries where RYMV has been reported: Benin, Burkina Faso (BF), Chad, Ivory Coast (CI), Cameroon, Ghana, Guinea, Kenya, Madagascar (Mg), Mali, Niger, Nigeria (Ni), Sierra Leone, Tanzania (Tz) and Togo. The Kimura2 substitution model with estimates of the alpha parameter of the gamma shape was applied. The serotype of the isolates defined by reactions with a set of monoclonal antibodies in ELISA tests (47) is indicated (by vertical bars) at the right of the figure.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: ORF4 (CP)-based phylogenetic tree. Phylogenetic tree reconstructed from 179 partially sequenced isolates from the 15 countries where RYMV has been reported: Benin, Burkina Faso (BF), Chad, Ivory Coast (CI), Cameroon, Ghana, Guinea, Kenya, Madagascar (Mg), Mali, Niger, Nigeria (Ni), Sierra Leone, Tanzania (Tz) and Togo. The Kimura2 substitution model with estimates of the alpha parameter of the gamma shape was applied. The serotype of the isolates defined by reactions with a set of monoclonal antibodies in ELISA tests (47) is indicated (by vertical bars) at the right of the figure.
Mentions: We used 10 fully sequenced RYMV isolates belonging to different serogroups and representative of viral diversity in Africa (i.e. with 9.9% maximum diversity) [19,23], these were; BF1, CI63, CI4, Ni1, Ni2, Mg1, Tz3, Tz5, Tz8 and Tz11. There was a second set of 10 isolates belonging to serogroup 2, showing variable pathogenicity assessed through symptom intensity, but low sequence diversity (2%). These were; CI110, 111, 112, 113, 114, 115, 116, 121, 129, and 138 [27] (Figure 2). They were independently propagated in the susceptible cultivar O. sativa spp. indica cv. IR64.

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