scholarly journals Transgenic Tobacco Plants Expressing the Potato virus X Open Reading Frame 3 Gene Develop Specific Resistance and Necrotic Ring Symptoms After Infection with the Homologous Virus

2001 ◽  
Vol 14 (11) ◽  
pp. 1274-1285 ◽  
Author(s):  
Ken Kobayashi ◽  
Silvia Cabral ◽  
Gabriela Calamante ◽  
Sara Maldonado ◽  
Alejandro Mentaberry
Keyword(s):  
Transgenic Plants ◽  
Potato Virus ◽  
Specific Resistance ◽  
Resistance Mechanism ◽  
Potato Virus X ◽  
Open Reading Frame ◽  
Morphological Aspect ◽  
Tobacco Plants ◽  
Reading Frame ◽  
Homologous Virus

Tobacco plants were transformed with the open reading frame 3 gene from Potato virus X (PVX) coding for the p12 protein. Although the transgenic plants exhibited a normal morphological aspect, microscopic examination revealed extensive alterations in leaf tissue structure. After being challenged with PVX, the transgenic plants showed resistance to PVX infection and formation of specific leaf symptoms consisting of concentric rings encircled by necrotic borders. These novel symptoms were accompanied by biochemical changes normally associated with the hypersensitive response (HR) and were absent in noninfected transgenic plants or in PVX-infected nontransgenic plants. No equivalent virus resistance was observed after inoculation with Tobacco mosaic virus or Potato virus Y, suggesting the presence of a specific resistance mechanism. Despite development of HR-like symptoms, systemic acquired resistance was not induced in PVX-infected p12 transgenic plants. No evidence of an RNA-mediated resistance mechanism was found.

scholarly journals Stability of recombinant plant viruses containing genes of unrelated plant viruses

2007 ◽  
Vol 88 (4) ◽  
pp. 1347-1355 ◽  
Author(s):  
Bong-Nam Chung ◽  
Tomas Canto ◽  
Peter Palukaitis
Keyword(s):  
Transgenic Plants ◽  
Transgenic Tobacco ◽  
Potato Virus ◽  
Tobacco Rattle Virus ◽  
Resistance Mechanism ◽  
Potato Virus X ◽  
Plant Viruses ◽  
Hybrid Plant ◽  
Expression Vectors ◽  
Post Inoculation

The stability of hybrid plant viruses that might arise by recombination in transgenic plants was examined using hybrid viruses derived from the viral expression vectors potato virus X (PVX) and tobacco rattle virus (TRV). The potato virus Y (PVY) NIb and HCPro open reading frames (ORFs) were introduced into PVX to generate PVX-NIb and PVX-HCPro, while the PVY NIb ORF was introduced into a vector derived from TRV RNA2 to generate TRV-NIb. All three viruses were unstable and most of the progeny viruses had lost the inserted sequences between 2 and 4 weeks post-inoculation. There was some variation in the rate of loss of part or all of the inserted sequence and the number of plants containing the deleted viruses, depending on the sequence, the host (Nicotiana tabacum vs Nicotiana benthamiana) or the vector, although none of these factors was associated consistently with the preferential loss of the inserted sequences. PVX-NIb was unable to accumulate in NIb-transgenic tobacco resistant to infection by PVY and also showed loss of the NIb insert from PVX-NIb in some NIb-transgenic tobacco plants susceptible to infection by PVY. These data indicate that such hybrid viruses, formed in resistant transgenic plants from a transgene and an unrelated virus, would be at a selective disadvantage, first by being targeted by the resistance mechanism and second by not being competitive with the parental virus.

scholarly journals Transgenic Plants Expressing Potato Virus X ORF2 Protein (p24) Are Resistant to Tobacco Mosaic Virus and Ob Tobamoviruses

1998 ◽  
Vol 72 (1) ◽  
pp. 731-738 ◽  
Author(s):  
X. Ares ◽  
G. Calamante ◽  
S. Cabral ◽  
J. Lodge ◽  
P. Hemenway ◽  
...  
Keyword(s):  
Transgenic Plants ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Transgenic Tobacco ◽  
Potato Virus ◽  
Potato Virus X ◽  
N Gene ◽  
Transgenic Tobacco Plants ◽  
Tobacco Plants ◽  
Virus Accumulation

ABSTRACT The p24 protein, one of the three proteins implicated in local movement of potato virus X (PVX), was expressed in transgenic tobacco plants (Nicotiana tabacum Xanthi D8 NN). Plants with the highest level of p24 accumulation exhibited a stunted and slightly chlorotic phenotype. These transgenic plants facilitate the cell-to-cell movement of a mutant of PVX that contained a frameshift mutation in p24. Upon inoculation with tobacco mosaic virus (TMV), the size of necrotic local lesions was significantly smaller in p24+ plants than in nontransgenic, control plants. Systemic resistance to tobamoviruses was also evidenced after inoculation of p24+ plants with Ob, a virus that evades the hypersensitive response provided by the N gene. In the latter case, no systemic symptoms were observed, and virus accumulation remained low or undetectable by Western immunoblot analysis and back-inoculation assays. In contrast, no differences were observed in virus accumulation after inoculation with PVX, although more severe symptoms were evident on p24-expressing plants than on control plants. Similarly, infection assays conducted with potato virus Y showed no differences between control and transgenic plants. On the other hand, a considerable delay in virus accumulation and symptom development was observed when transgenic tobacco plants containing the movement protein (MP) of TMV were inoculated with PVX. Finally, a movement defective mutant of TMV was inoculated on p24+ plants or in mixed infections with PVX on nontransgenic plants. Both types of assays failed to produce TMV infections, implying that TMV MP is not interchangeable with the PVX MPs.

scholarly journals Involvement of the chloroplast gene ferredoxin 1 in multiple responses of Nicotiana benthamiana to Potato virus X infection

2019 ◽  
Vol 71 (6) ◽  
pp. 2142-2156 ◽  
Author(s):  
Xue Yang ◽  
Yuwen Lu ◽  
Fang Wang ◽  
Ying Chen ◽  
Yanzhen Tian ◽  
...  
Keyword(s):  
Transgenic Plants ◽  
Mosaic Virus ◽  
Potato Virus ◽  
Tobacco Rattle Virus ◽  
Potato Virus X ◽  
Tomato Mosaic Virus ◽  
Pcr Analysis ◽  
Coat Proteins ◽  
Virus Induced Gene Silencing ◽  
Callose Deposition

Abstract The chloroplast protein ferredoxin 1 (FD1), with roles in the chloroplast electron transport chain, is known to interact with the coat proteins (CPs) of Tomato mosaic virus and Cucumber mosaic virus. However, our understanding of the roles of FD1 in virus infection remains limited. Here, we report that the Potato virus X (PVX) p25 protein interacts with FD1, whose mRNA and protein levels are reduced by PVX infection or by transient expression of p25. Silencing of FD1 by Tobacco rattle virus-based virus-induced gene silencing (VIGS) promoted the local and systemic infection of plants by PVX. Use of a drop-and-see (DANS) assay and callose staining revealed that the permeability of plasmodesmata (PDs) was increased in FD1-silenced plants together with a consistently reduced level of PD callose deposition. After FD1 silencing, quantitative reverse transcription–real-time PCR (qRT–PCR) analysis and LC-MS revealed these plants to have a low accumulation of the phytohormones abscisic acid (ABA) and salicylic acid (SA), which contributed to the decreased callose deposition at PDs. Overexpression of FD1 in transgenic plants manifested resistance to PVX infection, but the contents of ABA and SA, and the PD callose deposition were not increased in transgenic plants. Overexpression of FD1 interfered with the RNA silencing suppressor function of p25. These results demonstrate that interfering with FD1 function causes abnormal plant hormone-mediated antiviral processes and thus enhances PVX infection.

scholarly journals Tobacco mosaic virus (TMV) and potato virus X (PVX) coat proteins confer heterologous interference to PVX and TMV infection, respectively

2006 ◽  
Vol 87 (4) ◽  
pp. 1005-1012 ◽  
Author(s):  
A. A. Bazzini ◽  
S. Asurmendi ◽  
H. E. Hopp ◽  
R. N. Beachy
Keyword(s):  
Transgenic Plants ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Potato Virus ◽  
Quaternary Structure ◽  
Systemic Infection ◽  
Potato Virus X ◽  
Coat Proteins ◽  
Local Cell ◽  
Cell Spread

Replication of Potato virus X (PVX) was reduced in transgenic protoplasts that accumulated wild-type coat protein (CPWT) of Tobacco mosaic virus (TMV) or a mutant CP, CPT42W, that produced highly ordered states of aggregation, including pseudovirions. This reaction is referred to as heterologous CP-mediated resistance. However, protoplasts expressing a CP mutant that abolished aggregation and did not produce pseudovirions, CPT28W, did not reduce PVX replication. Similarly, in transgenic tobacco plants producing TMV CPWT or CPT42W, there was a delay in local cell-to-cell spread of PVX infection that was not observed in CPT28W plants or in non-transgenic plants. The results suggest that the quaternary structure of the TMV CP regulates the mechanism(s) of heterologous CP-mediated resistance. Similarly, transgenic protoplasts that produced PVX CP conferred transient protection against infection by TMV RNA. Transgenic plants that accumulated PVX CP reduced the cell-to-cell spread of infection and resulted in a delay in systemic infection following inoculation with TMV or TMV RNA. Heterologous CP-mediated resistance was characterized by a brief delay in systemic infection, whilst homologous CP-mediated resistance conferred reduced or no systemic infection.

Analysis of a translational enhancer upstream from the coat protein open reading frame of potato virus S

1994 ◽  
Vol 134 (3-4) ◽  
pp. 321-333 ◽  
Author(s):  
R. Turner ◽  
N. Bate ◽  
D. Twell ◽  
G. D. Foster
Keyword(s):  
Coat Protein ◽  
Potato Virus ◽  
Open Reading Frame ◽  
Potato Virus S ◽  
Reading Frame ◽  
Translational Enhancer

scholarly journals Characterization of the Recombinant Forms Arising from a Potato virus X Chimeric Virus Infection under RNA Silencing Pressure

2006 ◽  
Vol 19 (8) ◽  
pp. 904-913 ◽  
Author(s):  
D. Barajas ◽  
F. Tenllado ◽  
J. R. Díaz-Ruíz
Keyword(s):  
Transgenic Plants ◽  
Potato Virus ◽  
Rna Silencing ◽  
Defense Mechanism ◽  
Selective Pressure ◽  
Significant Proportion ◽  
Potato Virus X ◽  
Plum Pox Virus ◽  
Recombination Processes

Recombination is a frequent phenomenon in RNA viruses whose net result is largely influenced by selective pressures. RNA silencing in plants acts as a defense mechanism against viruses and can be used to engineer virus resistance. Here, we have investigated the influence of RNA silencing as a selective pressure to favor recombinants of PVX-HCT, a chimeric Potato virus X (PVX) vector carrying the helper-component proteinase (HC-Pro) gene from Plum pox virus (PPV). All the plants from two lines expressing a silenced HC-Pro transgene were completely resistant to PPV. However a significant proportion became infected with PVX-HCT. Analysis of viral RNAs accumulating in silenced plants revealed that PVX-HCT escaped silencing-based resistance by removal of the HC-Pro sequences that represented preferential targets for transgene-promoted silencing. The virus vector also tended to lose the HC-Pro insert when infecting transgenic plants containing a nonsilenced HC-Pro transgene or wild-type (wt) Nicotiana benthamiana plants. Nevertheless, loss of HC-Pro sequences was faster in nonsilenced transgenic plants than in wt plants, suggesting the transgene plays a role in promoting a higher selective pressure in favor of recombinant virus versions. These results indicate that the outcome of recombination processes depends on the strength of selection pressures applied to the virus.

scholarly journals The ORF1 Products of Tombusviruses Play a Crucial Role in Lethal Necrosis of Virus-Infected Plants

2000 ◽  
Vol 74 (23) ◽  
pp. 10873-10881 ◽  
Author(s):  
József Burgyán ◽  
Csaba Hornyik ◽  
György Szittya ◽  
Dániel Silhavy ◽  
György Bisztray
Keyword(s):  
Transgenic Plants ◽  
Viral Replication ◽  
Potato Virus ◽  
Nicotiana Benthamiana ◽  
Crucial Role ◽  
Viral Vector ◽  
Potato Virus X ◽  
Wild Type ◽  
Systemic Necrosis

ABSTRACT Hybrids of cymbidium ringspot (CymRSV) and carnation Italian ringspot (CIRV) tombusviruses were used to identify viral symptom determinants responsible for the generalized necrosis in tombusvirus-infected plants. Surprisingly, symptoms of Nicotiana benthamiana infected with CymRSV/CIRV hybrids were distinctly different. It was demonstrated that not all chimeras expressing wild-type (wt) levels of p19 protein caused systemic necrosis as both parents CymRSV and CIRV did. We showed here that hybrids containing chimeric ORF1 were not able to induce lethal necrosis even if the viral replication of these constructs was not altered significantly. However, if a wt p33 (product of ORF1) of CymRSV was provided intrans in transgenic plants expressing p33 and its readthrough product p92, the lethal necrosis characteristic to tombusvirus infection was restored. In addition, the expression of p33 by a potato virus X viral vector in N. benthamiana caused severe chlorosis and occasionally necrosis, indicating the importance of p33 in wt symptoms of tombusviruses. Thus, our results provide evidence that elicitation of the necrotic phenotype requires the presence of the wt p33 in addition to the p19 protein of tombusviruses.

scholarly journals Silencing of a viral RNA silencing suppressor in transgenic plants

2002 ◽  
Vol 83 (9) ◽  
pp. 2325-2335 ◽  
Author(s):  
Eugene I. Savenkov ◽  
Jari P. T. Valkonen
Keyword(s):  
Transgenic Plants ◽  
Rna Silencing ◽  
Vascular Tissue ◽  
Resistance Mechanism ◽  
Viral Rna ◽  
Post Inoculation ◽  
Silencing Suppressor ◽  
Homologous Virus ◽  
Close Proximity ◽  
Transgenic Lines

High expression levels of the helper component proteinase (HCpro), a known virus suppressor of RNA silencing, were attained in Nicotiana benthamiana transformed with the HCpro cistron of Potato virus A (PVA, genus Potyvirus). No spontaneous silencing of the HCpro transgene was observed, in contrast to the PVA coat protein (CP)-encoding transgene in other transgenic lines. HCpro-transgenic plants were initially susceptible to PVA and were systemically infected by 14 days post-inoculation (p.i.) but, 1 to 2 weeks later, the new expanding leaves at positions +6 and +7 above the inoculated leaf showed a peculiar recovery phenotype. Leaf tips (the oldest part of the leaf) were chlorotic and contained high titres of PVA, whereas the rest of the leaf was symptomless and contained greatly reduced or non-detectable levels of viral RNA, CP and transgene mRNA. The spatial recovery phenotype suggests that RNA silencing is initiated in close proximity to meristematic tissues. Leaves at position +8 and higher were symptomless and virus-free but not completely resistant to mechanical inoculation with PVA. However, they were not infected with the virus systemically transported from the lower infected leaves, suggesting a vascular tissue-based resistance mechanism. Recovery of the HCpro-transgenic plants from infection with different PVA isolates was dependent on the level of sequence homology with the transgene. Methylation of the HCpro transgene followed recovery. These data show that the transgene mRNA for a silencing suppressor can be silenced by a presumably ‘strong’ silencing inducer (replicating homologous virus).

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