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 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.;

Host-induced gene silencing and spray-induced gene silencing for crop protection against viruses.

2021 ◽  
pp. 72-85
Author(s):  
Angela Ricci ◽  
Silvia Sabbadini ◽  
Laura Miozzi ◽  
Bruno Mezzetti ◽  
Emanuela Noris
Keyword(s):  
Gene Silencing ◽  
Plant Pathogens ◽  
Crop Protection ◽  
Plant Defence ◽  
Transcriptional Gene Silencing ◽  
Target Sequence ◽  
Sequence Specificity ◽  
Rna Molecules ◽  
Political Concern ◽  
Post Transcriptional Gene Silencing

Abstract Since the beginning of agriculture, plant virus diseases have been a strong challenge for farming. Following its discovery at the very beginning of the 1990s, the RNA interference (RNAi) mechanism has been widely studied and exploited as an integrative tool to obtain resistance to viruses in several plant species, with high target-sequence specificity. In this chapter, we describe and review the major aspects of host-induced gene silencing (HIGS), as one of the possible plant defence methods, using genetic engineering techniques. In particular, we focus our attention on the use of RNAi-based gene constructs to introduce stable resistance in host plants against viral diseases, by triggering post-transcriptional gene silencing (PTGS). Recently, spray-induced gene silencing (SIGS), consisting of the topical application of small RNA molecules to plants, has been explored as an alternative tool to the stable integration of RNAi-based gene constructs in plants. SIGS has great and innovative potential for crop defence against different plant pathogens and pests and is expected to raise less public and political concern, as it does not alter the genetic structure of the plant.

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 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 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 Effects of the Crinivirus Coat Protein–Interacting Plant Protein SAHH on Post-Transcriptional RNA Silencing and Its Suppression

2013 ◽  
Vol 26 (9) ◽  
pp. 1004-1015 ◽  
Author(s):  
M. Carmen Cañizares ◽  
Rosa Lozano-Durán ◽  
Tomás Canto ◽  
Eduardo R. Bejarano ◽  
David M. Bisaro ◽  
...  
Keyword(s):  
Coat Protein ◽  
Rna Silencing ◽  
Rna Degradation ◽  
Plant Viruses ◽  
Plant Protein ◽  
Transcriptional Gene Silencing ◽  
Small Interfering Rnas ◽  
Post Transcriptional Gene Silencing ◽  
Secondary Sirnas ◽  
Tomato Chlorosis Virus

In plants, post-transcriptional gene silencing (PTGS) is a sequence-specific mechanism of RNA degradation induced by double-stranded RNA (dsRNA), which is processed into small interfering RNAs (siRNAs). siRNAs are methylated and, thereby, stabilized by the activity of the S-adenosylmethionine-dependent RNA methyltransferase HEN1. PTGS is amplified by host-encoded RNA-dependent RNA polymerases (RDR), which generate dsRNA that is processed into secondary siRNAs. To counteract this RNA silencing-mediated response of the host, plant viruses express proteins with silencing suppression activity. Here, we report that the coat protein (CP) of crinivirus (family Closteroviridae, genus Crinivirus) Tomato chlorosis virus, a known suppressor of silencing, interacts with S-adenosylhomocysteine hydrolase (SAHH), a plant protein essential for sustaining the methyl cycle and S-adenosylmethionine-dependent methyltransferase activity. Our results show that, by contributing to an increased accumulation of secondary siRNAs generated by the action of RDR6, SAHH enhances local RNA silencing. Although downregulation of SAHH prevents local silencing, it enhances the spread of systemic silencing. Our results also show that SAHH is important in the suppression of local RNA silencing not only by the crinivirus Tomato chlorosis virus CP but also by the multifunctional helper component-proteinase of the potyvirus Potato virus Y.

scholarly journals New Advances in Understanding the Molecular Biology of Plant/Potyvirus Interactions

1999 ◽  
Vol 12 (5) ◽  
pp. 367-376 ◽  
Author(s):  
Frédéric Revers ◽  
Olivier Le Gall ◽  
Thierry Candresse ◽  
Andrew J. Maule
Keyword(s):  
New Technologies ◽  
Systemic Infection ◽  
Seed Transmission ◽  
Plant Viruses ◽  
Transcriptional Gene Silencing ◽  
Post Transcriptional Gene Silencing ◽  
Molecular Determinants ◽  
Engineered Resistance ◽  
Recent Developments ◽  
Key Aspects

In recent years, researchers have adopted many new technologies to help understand potyvirus pathogenesis. Their findings have illuminated key aspects of the interactions between the host and the virus, and between the virus and its aphid vector. This review focuses on advances in our understanding of the molecular determinants of systemic infection, symptom expression, aphid and seed transmission, and natural and engineered resistance to potyviruses. Very recent developments in the area of post-transcriptional gene silencing indicate not only that the process is fundamental to engineered resistance, but may also underlie many aspects of the biology of plant viruses.

Host-induced gene silencing and spray-induced gene silencing for crop protection against viruses.

2021 ◽  
pp. 72-85
Author(s):  
Angela Ricci ◽  
Silvia Sabbadini ◽  
Laura Miozzi ◽  
Bruno Mezzetti ◽  
Emanuela Noris
Keyword(s):  
Gene Silencing ◽  
Plant Pathogens ◽  
Crop Protection ◽  
Plant Defence ◽  
Transcriptional Gene Silencing ◽  
Target Sequence ◽  
Sequence Specificity ◽  
Rna Molecules ◽  
Political Concern ◽  
Post Transcriptional Gene Silencing

Abstract Since the beginning of agriculture, plant virus diseases have been a strong challenge for farming. Following its discovery at the very beginning of the 1990s, the RNA interference (RNAi) mechanism has been widely studied and exploited as an integrative tool to obtain resistance to viruses in several plant species, with high target-sequence specificity. In this chapter, we describe and review the major aspects of host-induced gene silencing (HIGS), as one of the possible plant defence methods, using genetic engineering techniques. In particular, we focus our attention on the use of RNAi-based gene constructs to introduce stable resistance in host plants against viral diseases, by triggering post-transcriptional gene silencing (PTGS). Recently, spray-induced gene silencing (SIGS), consisting of the topical application of small RNA molecules to plants, has been explored as an alternative tool to the stable integration of RNAi-based gene constructs in plants. SIGS has great and innovative potential for crop defence against different plant pathogens and pests and is expected to raise less public and political concern, as it does not alter the genetic structure of the plant.

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