Expression of the Potato Leafroll Virus ORF0 Induces Viral-Disease-like Symptoms in Transgenic Potato Plants

Wilk, F. van der; Houterman, Petra M.; Molthoff, Jos; Hans, Fabienne; Dekker, B.M.M.; Heuvel, J. van den; Huttinga, H.; Goldbach, Rob

doi:10.1094/mpmi.1997.10.2.153

Cited by 45 publications

(18 citation statements)

References 34 publications

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“…(However, the reported ability of HCPro to traffic from cell to cell [33] could complicate the interpretive comparison of data from the two types of experiment.) Nevertheless, it is evident that characterization of P0-transgenic plants will be of interest in the future, although production of such plants may be hindered by the reported cytopathic effects of P0 when expressed in this manner (37).…”

Section: Discussionmentioning

confidence: 99%

P0 of Beet Western Yellows Virus Is a Suppressor of Posttranscriptional Gene Silencing

Pfeffer

Dunoyer

Heim

et al. 2002

J Virol

202

144

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Higher plants employ a homology-dependent RNA-degradation system known as posttranscriptional gene silencing (PTGS) as a defense against virus infection. Several plant viruses are known to encode proteins that can suppress PTGS. Here we show that P0 of beet western yellows virus (BWYV) displays strong silencing suppressor activity in a transient expression assay based upon its ability to inhibit PTGS of green fluorescent protein (GFP) when expressed in agro-infiltrated leaves of Nicotiana benthamiana containing a GFP transgene. PTGS suppressor activity was also observed for the P0s of two other poleroviruses, cucurbit aphid-borne yellows virus and potato leafroll virus. P0 is encoded by the 5-proximal gene in BWYV RNA but does not accumulate to detectable levels when expressed from the genome-length RNA during infection. The low accumulation of P0 and the resulting low PTGS suppressor activity are in part a consequence of the suboptimal translation initiation context of the P0 start codon in viral RNA, although other factors, probably related to the viral replication process, also play a role. A mutation to optimize the P0 translation initiation efficiency in BWYV RNA was not stable during virus multiplication in planta. Instead, the P0 initiation codon in the progeny was frequently replaced by a less efficient initiation codon such as ACG, GTG, or ATA, indicating that there is selection against overexpression of P0 from the viral genome.Most if not all plants possess a defense mechanism against virus infection known as posttranscriptional gene silencing (PTGS; see reference 44 for a recent review). PTGS is a homology-dependent RNA degradation system to recognize and degrade viral RNA (and any homologous transgene mRNA) in the cytoplasm. Mechanistically similar phenomena exist in animals and fungi (reviewed in references 4, 13, and 35). The mechanism by which a virus infection triggers PTGS in plants is not fully understood, but double-stranded RNA is a strong inducer of PTGS (43) and such a form is produced during replication of an RNA virus. Production of small RNAs of ϳ21 to 23 nucleotides, called small interfering RNAs (siRNAs), corresponding to both the plus and minus strands of the target RNA is associated with PTGS (12,13,45). In plants, gene silencing at one site can trigger PTGS in distant tissues and across a graft union (29, 39a). The mobile signal, which must consist at least in part of homologous RNA, is thought to move from cell to cell through plasmodesmata and systemically via the vasculature. Some plant viruses have been shown to encode proteins which can counteract PTGS (8,22,39,40,42). These silencing suppressor proteins may act at different steps in the PTGS pathway. Thus, (i) the potyvirus helper component-proteinase (HCPro) interferes with initiation and maintenance of silencing at a step coincident with or upstream of siRNA production (1,7,16,23,24), (ii) the 2b protein of cucumber mosaic virus (CMV) prevents initiation of PTGS in new growth by inhibiting the long-range PTGS signaling acti...

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Section: Discussionmentioning

confidence: 99%

P0 of Beet Western Yellows Virus Is a Suppressor of Posttranscriptional Gene Silencing

Pfeffer

Dunoyer

Heim

et al. 2002

J Virol

202

144

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“…Precisely how the DNA␤ ␤C1 protein controls symptom expression is unclear. Some of the gene products of RNA viruses that induce symptoms in transgenic plants, such as the P0 protein of poleroviruses and P19 protein of tombusviruses, also act as suppressors of posttranscriptional gene silencing (19,25,27). Preliminary evidence suggests that the ␤C1 protein may have a similar function (16).…”

Section: Discussionmentioning

confidence: 99%

A DNAβ Associated with Tomato Yellow Leaf Curl China Virus Is Required for Symptom Induction

Cui

Tao

Xie

et al. 2004

J Virol

267

320

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We report here that all 25 isolates of Tomato yellow leaf curl China virus (TYLCCNV) collected from tobacco, tomato, or Siegesbeckia orientalis plants in different regions of Yunnan Province, China, were associated with DNA␤ molecules. To investigate the biological role of DNA␤, full-length infectious clones of viral DNA and DNA␤ of TYLCCNV isolate Y10 (TYLCCNV-Y10) were agroinoculated into Nicotiana benthamiana, Nicotiana glutinosa, Nicotiana. tabacum Samsun (NN or nn), tomato, and petunia plants. We found that TYLCCNV-Y10 alone could systemically infect these plants, but no symptoms were induced. TYLCCNV-Y10 DNA␤ was required, in addition to TYLCCNV-Y10, for induction of leaf curl disease in these hosts. Similar to TYLCCNV-Y10, DNA␤ of TYLCCNV isolate Y64 was also found to be required for induction of typical leaf curl diseases in the hosts tested. When the ␤C1 gene of TYLCCNV-Y10 DNA␤ was mutated, the mutants failed to induce leaf curl symptoms in N. benthamiana when coinoculated with TYLCCNV-Y10. However, Southern blot hybridization analyses showed that the mutated DNA␤ molecules were replicated. When N. benthamiana and N. tabacum plants were transformed with a construct containing the ␤C1 gene under the control of the Cauliflower mosaic virus 35S promoter, many transgenic plants developed leaf curl symptoms similar to those caused by a virus, the severity of which paralleled the level of ␤C1 transcripts, while transgenic plants transformed with the ␤C1 gene containing a stop codon after the start codon remained symptomless. Thus, expression of a ␤C1 gene is adequate for induction of symptoms of viral infection in the absence of virus.

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“…This virus possesses a 5.9 kDa genome consisting of a single strand RNA molecule with plus orientation that encodes six open reading frames (ORF) (van der Wilk et al, 1997). Three of these frames are located near the 3´end and encode, through subgenomic RNA molecules, the 23 kDa coat protein (CP) (Van der Wilk et al, 1989), a 17 kDa floematic movement protein (MP) (Sokolova et al, 1997) and a 56 kDa protein involved in the virus/vector aphid interaction (Chay et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…The ORFs located near the 5´ end of the genome encode directly from genomic RNA several proteins (Matthews, 1991). The protein VPg and a 70 kDa protein (van der Wilk et al, 1997) is encoded by the first ORF (Gorbalenya et al, 1989). The second ORF encodes a 28 kDa protein of unknown function, whereas the third is thought to encode a 69 kDa replicase (Koonin, 1991).…”

Section: Introductionmentioning

confidence: 99%

Replicase mediated resistance against Potato Leafroll Virus in potato Desirée plants

et al. 2004

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Potato leafroll virus (PLRV) is a major menace for the potato production all over the world. PLRV is transmitted by aphids, and until now, the only strategy available to control this pest has been to use large amounts of insecticides. Transgenic approaches involving the expression of viral replicases are being developed to provide protection for plants against viral diseases. The purpose of this study was to compare the protection afforded by the differential expression of PLRV replicase transgene in potato plants cv. Desirée. Plants were genetically modified to express the complete sense PLRV replicase gene. Two constructions were used, one containing the constitutive 35SCaMV promoter and the other the phloem-specific RolA promoter from Agrobacterium rhizogenes. Transgenic plants were infected with PLRV in vitro, using infested aphids. In plants in which 35SCaMV controlled the expression of the PLRV replicase gene, signs of infection were initially detected, although most plants later developed a recovery phenotype showing undetectable virus levels 40 days after infection. In turn, those plants with the RolA promoter displayed an initial resistance that was later overcome. Different molecular mechanisms are likely to participate in the response to PLRV infection of these two types of transgenic plants.

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Expression of the Potato Leafroll Virus ORF0 Induces Viral-Disease-like Symptoms in Transgenic Potato Plants

Cited by 45 publications

References 34 publications

P0 of Beet Western Yellows Virus Is a Suppressor of Posttranscriptional Gene Silencing

P0 of Beet Western Yellows Virus Is a Suppressor of Posttranscriptional Gene Silencing

A DNAβ Associated with Tomato Yellow Leaf Curl China Virus Is Required for Symptom Induction

Replicase mediated resistance against Potato Leafroll Virus in potato Desirée plants

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