scholarly journals Pathogen derived resistance to Potato virus Y: mechanisms and risks

1999 ◽  
Vol 8 (4-5) ◽  
pp. 493-513 ◽  
Author(s):  
T. MÄKI-VALKAMA ◽  
J.P.T VALKONEN
Keyword(s):  
Potato Virus ◽  
Potato Virus Y ◽  
Resistance Mechanisms ◽  
Transcriptional Gene Silencing ◽  
Virus Infections ◽  
Post Transcriptional Gene Silencing ◽  
Expression Studies ◽  
Natural Protection ◽  
Pathogen Derived Resistance ◽  
Helper Component Proteinase

Since the concept of pathogen derived resistance (PDR) was proposed in 1985, genetic transformation of plants to express virus-derived sequences has been used to engineer resistance to many viruses. This paper reviews PDR approaches to Potato virus Y (PVY, type member of the genus Potyvirus). PDR to viruses operates often through RNA-mediated resistance mechanisms that do not require protein expression. Studies on the RNA-mediated resistance have led to the discovery of post-transcriptional gene silencing (PTGS), a mechanism that controls gene expression in eukaryotic cells and provides natural protection against virus infections. Viruses, in turn, can suppress the PTGS with some of their proteins, such as the helper component-proteinase protein of PVY. Expression of PVY proteins in transgenic plants entails a risk for heterologous encapsidation or synergism with viruses that infect the PVY-resistant transgenic plant. These risks are avoided using RNA-mediated resistance, but a risk still exists for recombination between the transgene transcript and the RNA genome of the infecting virus, which may create a virus with altered properties. The harmful consequences can be limited to some extent by removing functional motifs from the viral sequence used as a transgene.;

scholarly journals Cucumber mosaic virus Infection Transiently Breaks dsRNA-Induced Transgenic Immunity to Potato virus Y in Tobacco

2003 ◽  
Vol 16 (10) ◽  
pp. 936-944 ◽  
Author(s):  
Neena Mitter ◽  
Emy Sulistyowati ◽  
Ralf G. Dietzgen
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Potato Virus ◽  
Potato Virus Y ◽  
Defense Mechanism ◽  
Transcriptional Gene Silencing ◽  
Mrna Levels ◽  
Post Transcriptional Gene Silencing ◽  
The Stability ◽  
High Level

Post-transcriptional gene silencing (PTGS), an intrinsic plant defense mechanism, can be efficiently triggered by double stranded (ds)RNA-producing transgenes and can provide high level virus resistance by specific targeting of cognate viral RNA. The discovery of virus-encoded suppressors of PTGS led to concerns about the stability of such resistance. Here, we show that Cucumber mosaic virus (CMV) is able to suppress dsRNA-induced PTGS and the associated Potato virus Y (PVY) immunity in tobacco. CMV suppression supported only a transient PVY accumulation and did not prevent recovery of the transgenic plants from PVY infection. CMV inoculation resulted in strongly increased transgene mRNA levels due to suppression of PTGS, but accumulation of PVY-specific small interfering (si)RNA was unaffected. However, PVY accumulation in previously immune plants resulted in increased PVY siRNA levels and transgene mRNA was no longer detected, despite the presence of CMV. Transgene mRNA returned to high levels once PVY was no longer detected in CMV-infected plants. Recovered and chronically CMV-infected tissues were immune to further PVY infection.

scholarly journals Analysis of potyvirus terminal protein VPg-transgenic Arabidopsis thaliana plants.

2011 ◽  
Vol 58 (3) ◽  
Author(s):  
Izabela Wojtal ◽  
Paulina Piontek ◽  
Renata Grzela ◽  
Artur Jarmołowski ◽  
Włodzimierz Zagórski ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Potato Virus Y ◽  
Transgenic Arabidopsis ◽  
Early Stage ◽  
Transcriptional Gene Silencing ◽  
Transgenic Arabidopsis Thaliana ◽  
Post Transcriptional Gene Silencing ◽  
Correct Sequence ◽  
Transgenic Seeds ◽  
Pathogen Derived Resistance

Virus-coded VPg protein of Potato virus Y (PVY) does not have homologs apart from other VPgs. Since VPg is indispensable for the potyvirus life cycle, it appeared a good candidate for eliciting pathogen-derived resistance to PVY. Following agroinfection used to obtain PVY VPg-transgenic Arabidopsis thaliana plants, only few transgenic seeds were recovered giving rise to six transgenic plants that contained the VPg gene with the correct sequence. They generated VPg mRNA, but VPg protein was not detected. Some plants were immune to PVY infection suggesting post-transcriptional gene silencing. However, the likely PVY VPg toxicity exerted at an early stage of transformed seeds development precludes its use for engineering pathogen-derived resistance.

scholarly journals A critical appraisal of non conventional resistance to plant viruses

2002 ◽  
Vol 38 (SI 1 - 6th Conf EFPP 2002) ◽  
pp. S15-S20
Author(s):  
G.P. Martelli
Keyword(s):  
Plant Pathogens ◽  
Resistance Mechanisms ◽  
Plant Viruses ◽  
Natural Resistance ◽  
Transcriptional Gene Silencing ◽  
Infectious Agents ◽  
Transgenic Resistance ◽  
Genetic Incompatibility ◽  
Post Transcriptional Gene Silencing ◽  
Pathogen Derived Resistance

Among natural resistance mechanisms to plant pathogens, cultivar resistance has been extensively used in plant breeding to introduce what can be defined as “conventional” resistance to a number of them, including viruses. The necessity of overcoming the constraints of genetic incompatibility, so as to widen the range of possibile use of genetic control of infectious agents, has propitiated the utilization of biotechnological procedures, whereby “non conventional” or transgenic resistance was developed. Transgenic resistance to plant viruses encompasses the identification, cloning and tranferring into the recipient host of single viral genes, which gives rise to what is known as “pathogen-derived resistance” (PDR). Of the hypothesized mechanisms underlying expression of PDR, post-transcriptional gene silencing has been most extensively investigated in recent years. Despite of the success that virus-resistant cropping of transgenic plants begins to enjoy, in Europe there is still a widespread sentiment against agricultural biotechnologies and the use of genetically modified plants in particular. Yet, experimental evidence is accumulating that, in the case of PDR, the feared risks associated with genetic trasformation are minimal, if not negligible

scholarly journals Twenty Years of Transgenic Plants Resistant to Cucumber mosaic virus

2008 ◽  
Vol 21 (6) ◽  
pp. 675-684 ◽  
Author(s):  
Marco Morroni ◽  
Jeremy R. Thompson ◽  
Mark Tepfer
Keyword(s):  
Transgenic Plants ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Transcriptional Gene Silencing ◽  
Effective Strategies ◽  
Resistance Strategies ◽  
Post Transcriptional Gene Silencing ◽  
Viral Coat ◽  
Viral Replicase ◽  
Pathogen Derived Resistance

Plant genetic engineering has promised researchers improved speed and flexibility with regard to the introduction of new traits into cultivated crops. A variety of approaches have been applied to produce virus-resistant transgenic plants, some of which have proven to be remarkably successful. Studies on transgenic resistance to Cucumber mosaic virus probably have been the most intense of any plant virus. Several effective strategies based on pathogen-derived resistance have been identified; namely, resistance mediated by the viral coat protein, the viral replicase, and post-transcriptional gene silencing. Techniques using non-pathogen-derived resistance strategies, some of which could offer broader resistance, generally have proven to be much less effective. Not only do the results obtained so far provide a useful guide to help focus on future strategies, but they also suggest that there are a number of possible mechanisms involved in conferring these resistances. Further detailed studies on the interplay between viral transgene-derived molecules and their host are needed in order to elucidate the mechanisms of resistance and pathogenicity.

scholarly journals A Viral Protein Suppresses siRNA-directed Interference in Tobacco Mosaic Virus Infection

2005 ◽  
Vol 37 (4) ◽  
pp. 248-253 ◽  
Author(s):  
Ming-Min Zhao ◽  
De-Rong An ◽  
Guang-Hua Huang ◽  
Zu-Hua He ◽  
Jiang-Ye Chen
Keyword(s):  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Plant Viruses ◽  
Negative Control ◽  
Transcriptional Gene Silencing ◽  
Potato Virus A ◽  
Post Transcriptional Gene Silencing ◽  
Tobacco Mosaic Virus Infection ◽  
Helper Component Proteinase ◽  
Rna Accumulation

Abstract Plant viruses encode suppressors of post-transcriptional gene silencing (PTGS), an adaptive defense response that limits virus replication and its spread in plants. The helper component proteinase (HC-Pro) of the potato virus A (PVA, genus Potyvirus) suppresses PTGS of silenced transgenes. Here, the effect of HC-Pro on siRNA-directed interference in the tobacco mosaic virus (TMV) was examined by using a transient Agrobacterium tumefaciens-based delivery system in intact tissues. It was shown that the interference effect was completely blocked by co-infiltration with HC-Pro plus siRNA constructs in both systemic and hypersensitive hosts. In the system host, all plants agro-infiltrated with HC-Pro plus siRNA constructs displayed the same symptoms as the negative control. Meanwhile, TMV RNA accumulation was found to be abundant in the upper leaves using reverse transcriptase-PCR (RT-PCR) and Northern blot assays. On the contrary, plants agro-infiltrated with the siRNA construct alone were free of symptoms. Therefore, our study suggests that the transient expression of HC-Pro inhibited the siRNA-directed host defenses against TMV infection.

scholarly journals Mutation of a Short Variable Region in HCpro Protein of Potato virus A Affects Interactions with a Microtubule-Associated Protein and Induces Necrotic Responses in Tobacco

2013 ◽  
Vol 26 (7) ◽  
pp. 721-733 ◽  
Author(s):  
Tuuli Haikonen ◽  
Minna-Liisa Rajamäki ◽  
Yan-Ping Tian ◽  
Jari P. T. Valkonen
Keyword(s):  
Conformational Changes ◽  
Potato Virus ◽  
Potato Virus Y ◽  
Variable Region ◽  
Host Cells ◽  
Multifunctional Protein ◽  
Host Interactions ◽  
Potato Virus A ◽  
Polymerase Chain ◽  
Helper Component Proteinase

Helper component proteinase (HCpro) is a multifunctional protein of potyviruses (genus Potyvirus). HCpro of Potato virus A (PVA) interacts with the microtubule-associated protein HIP2 in host cells, and depletion of HIP2 reduces virus accumulation. This study shows that HCpro of Potato virus Y and Tobacco etch virus also interact with HIP2. The C-proximal portion of PVA HCpro determines the interaction with HIP2 and was found to contain a stretch of six residues comprising a highly variable region (HVR) in potyviruses. Mutations in HVR reduced PVA accumulation in tobacco plants and induced necrotic symptoms novel to PVA. Microarray and quantitative reverse transcription polymerase chain reaction analyses revealed induction of many defense-related genes including ethylene- and jasmonic acid–inducible pathways in systemically infected leaves at necrosis onset. Salicylic acid–mediated signaling was dispensable for the response. Genes related to microtubule functions were down-regulated. Structural modeling of HCpro suggested that all mutations in HVR caused conformational changes in adjacent regions containing functionally important motifs conserved in potyviruses. Those mutations, which also caused conformational changes in HVR, led to the greatest reduction of fitness. Our results implicate HVR in the regulation of HCpro conformation and virus-host interactions and suggest that mutation of HVR induces host defense.

Sign in / Sign up

Export Citation Format

Share Document