Two proteins encoded by beet necrotic yellow vein virus RNA 3 influence symptom phenotype on leaves.

Beet necrotic yellow vein virus (BNYVV)-infected sugarbeets were obtained from many parts of Europe and also from some sites in Asia and the U.S.A. Reverse transcription (RT)-PCR products of more than I kbp were obtained for four different regions of the viral genome which may be particularly important with respect to the pathogenic properties of the virus, i.e. for the coat protein and the 42K protein-encoding regions on RNA 2 and for major parts ofRNAs 3 and 4. Restriction fragment length polymorphism (RFLP) patterns obtained with these PCR products revealed the existence of two major strain groups of BNYVV, named type A and type B. The A type was detected in Greece, the former Yugoslavia, Slovakia, parts of Austria, Italy, Spain, parts of France, Belgium, The Netherlands and England as well as in Asia (Turkey, Kazachstan, China and Japan) and the U.S.A. The B type occurs in Germany and parts of France. Mixed infections were detected at the borderline regions between areas of the A and B types. Comparisons of published and newly determined nucleotide sequences of the respective parts of the BNYVV genome indicate that the percentage of nucleotide differences between the A and the B type is approximately 3 % for the respective regions of RNAs 2 and 3 and approximately 1.5 % for RNA 4. Nucleotide sequences appear to be remarkably stable within each of the two strain groups. The majority of the nucleotide differences between the A and B types occur in the third triplet position. The amino acid changes in the coat protein area are outside the four previously determined antigenic regions that are accessible on the surface of the virus particles and are involved in the formation of continuous and presumably also discontinuous epitopes. This may explain why serological differences between the two strain groups have not been found.

Section: Resultsmentioning

confidence: 99%

Restriction fragment length polymorphism analysis of reverse transcription-PCR products reveals the existence of two major strain groups of beet necrotic yellow vein virus

Kruse¹,

Koenig²,

Hoffmann³

et al. 1994

“…We used a BNYVV RNA3-based replicon (Jupin et al, 1992;Bleykasten-Grosshans et al, 1997;Guilley et al, 2009) as an amplification-translation vector to express P0 proteins of different poleroviruses. To assess the capacity of P0 BC and P0 BM to cross-complement the RSS activity of BNYVV P14, we used infectious transcripts comprising RNA1+2DP14 of BNYVV strain F2 (Quillet et al, 1989), an artificial strain deficient in P14 synthesis (Hehn et al, 1995).…”

Section: P0mentioning

confidence: 99%

P0 proteins of European beet-infecting poleroviruses display variable RNA silencing suppression activity

Kozlowska-Makulska

Guilley

Szyndel

et al. 2009

Self Cite

Post-transcriptional gene silencing (PTGS), or RNA silencing, is one of the key mechanisms of antiviral defence used by plants. To counter this defence response, viruses produce suppressor proteins that are able to inhibit the PTGS pathway or to interfere with some of its function. The aim of this study was to evaluate the RNA silencing suppressor (RSS) activity of P0 proteins from selected European isolates of the beet-infecting poleroviruses beet chlorosis virus (BChV) and beet mild yellowing virus (BMYV) using two different experimental systems: (i) agro-infiltration of Nicotiana benthamiana green fluorescent protein-positive plants and (ii) mechanical inoculation of Chenopodium quinoa using a beet necrotic yellow vein virus (BNYVV, genus Benyvirus) RNA3-based replicon. The results demonstrated that P0 of most BMYV isolates exhibited RSS activity, although at various efficiencies among isolates. Conversely, P0 of BChV isolates displayed no RSS activity in either of the two systems under the experimental conditions used. These results are the first reported evidence that P0 proteins of two closely related beet poleroviruses show strain-specific differences in their effects on RNA silencing.

“…As shown in Table 2, infection with a triple mutant (Y68F/ R70G/D179N) resulted in the resistance phenotype in both MR1 and MR2 plants, whereas double mutants (Y68F/ Table 2). The nuclear localization signal (NLS), tetrad amino acid motif (aa 67-70), cysteine-rich region, nuclear export signal (NES) and acidic region are shown (Jupin et al, 1992;Vetter et al, 2004;Schirmer et al, 2005;Klein et al, 2007).…”

Section: Identification Of Amino Acids That Determine the Resistance mentioning

confidence: 99%

“…maritima) plants; the results showed that resistance and susceptibility to BNYVV could be assessed based on the phenotype on the inoculated leaves (Tamada, 2007). Considering previous studies that demonstrated the role of RNA3-encoded p25 in the exacerbation of virus-induced symptoms on inoculated leaves (Jupin et al, 1992;Tamada et al, 1999;Klein et al, 2007) and the role of its subcellular localization (Vetter et al, 2004), we assumed that p25 could be involved in the resistance response of the inoculated leaves.…”

Section: Introductionmentioning

confidence: 96%

“…RNA3, RNA4 and RNA5 are associated with vector-mediated infection and disease development in sugar beet roots. The RNA3-encoded p25 protein is responsible for the induction of rhizomania symptoms of sugar beet roots and severe symptom expression in Chenopodiaceae hosts (Tamada et al, 1989Jupin et al, 1992;Klein et al, 2007), whereas RNA4-encoded p31 is involved in efficient vector transmission and root-specific silencing suppression (Rahim et al, 2007). RNA5, which is also associated with symptom severity, has been found in small areas of Europe and in most areas of Asia (Miyanishi et al, 1999;Schirmer et al, 2005;Ward et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Identification of amino acids of the beet necrotic yellow vein virus p25 protein required for induction of the resistance response in leaves of Beta vulgaris plants

Chiba

Miyanishi

Andika

et al. 2008

The RNA3-encoded p25 protein of beet necrotic yellow vein virus (BNYVV) is responsible for the production of rhizomania symptoms of sugar beet roots (Beta vulgaris subsp. vulgaris). Here, it was found that the presence of the p25 protein is also associated with the resistance response in rub-inoculated leaves of sugar beet and wild beet (Beta vulgaris subsp. maritima) plants. The resistance phenotype displayed a range of symptoms from no visible lesions to necrotic or greyish lesions at the inoculation site, and only very low levels of virus and viral RNA accumulated. The susceptible phenotype showed large, bright yellow lesions and developed high levels of virus accumulation. In roots after Polymyxa betae vector inoculation, however, no drastic differences in virus and viral RNA accumulation levels were found between plants with susceptible and resistant phenotypes, except at an early stage of infection. There was a genotype-specific interaction between BNYVV strains and two selected wild beet lines (MR1 and MR2) and sugar beet cultivars. Sequence analysis of natural BNYVV isolates and site-directed mutagenesis of the p25 protein revealed that 3 aa residues at positions 68, 70 and 179 are important in determining the resistance phenotype, and that host-genotype specificity is controlled by single amino acid changes at position 68. The mechanism of the occurrence of resistance-breaking BNYVV strains is discussed.