scholarly journals Efficient Infection of Nicotiana benthamiana by Tomato bushy stunt virus Is Facilitated by the Coat Protein and Maintained by p19 Through Suppression of Gene Silencing

2002 ◽  
Vol 15 (3) ◽  
pp. 193-202 ◽  
Author(s):  
Feng Qu ◽  
T. Jack Morris

Tomato bushy stunt virus (TBSV) is one of few RNA plant viruses capable of moving systemically in some hosts in the absence of coat protein (CP). TBSV also encodes another protein (p19) that is not required for systemic movement but functions as a symptom determinant in Nicotiana ben-thamiana. Here, the role of both CP and p19 in the systemic spread has been reevaluated by utilizing transgenic N. ben-thamiana plants expressing the movement protein (MP) of Red clover necrotic mosaic virus and chimeric TBSV mutants that express CP of Turnip crinkle virus. Through careful examination of the infection phenotype of a series of mutants with changes in the CP and p19 genes, we demonstrate that both of these genes are required for efficient systemic invasion of TBSV in N. benthamiana. The CP likely enables efficient viral unloading from the vascular system in the form of assembled virions, whereas p19 enhances systemic infection by suppressing the virus-induced gene silencing.

1998 ◽  
Vol 11 (7) ◽  
pp. 706-709 ◽  
Author(s):  
Robert T. Lartey ◽  
Soumitra Ghoshroy ◽  
Vitaly Citovsky

Following inoculation, many plant viruses spread locally from cell to cell until they reach the vascular system, through which they then move to other parts of the plant, resulting in systemic infection. To isolate host genes involved in systemic transport of plant viruses, ethyl methanesulfonate-mutagenized Arabidopsis thaliana plants were screened for significant delays in the systemic movement of turnip vein clearing virus (TCVC). One such mutant, designated vsm1 (virus systemic movement), was identified. Unlike the wild-type plants, vsm1 did not develop viral disease and did not allow the systemic spread of the virus. The local viral movement within the inoculated vsm1 leaves, however, was not affected. TVCV systemic movement within the vsm1 plants was likely blocked at the step of viral entry into the host plant vasculature from the infected leaf tissue. vsm1 plants also restricted the systemic movement of another tobamovirus but not of an unrelated carmovirus.


2014 ◽  
Vol 11 (98) ◽  
pp. 20140555 ◽  
Author(s):  
Guillermo Rodrigo ◽  
Mark P. Zwart ◽  
Santiago F. Elena

The cornerstone of today's plant virology consists of deciphering the molecular and mechanistic basis of host–pathogen interactions. Among these interactions, the onset of systemic infection is a fundamental variable in studying both within- and between-host infection dynamics, with implications in epidemiology. Here, we developed a mechanistic model using probabilistic and spatio-temporal concepts to explain dynamic signatures of virus systemic infection. The model dealt with the inherent characteristic of plant viruses to use two different and sequential stages for their within-host propagation: cell-to-cell movement from the initial infected cell and systemic spread by reaching the vascular system. We identified the speed of cell-to-cell movement and the number of primary infection foci in the inoculated leaf as the key factors governing this dynamic process. Our results allowed us to quantitatively understand the timing of the onset of systemic infection, describing this global process as a consequence of local spread of viral populations. Finally, we considered the significance of our predictions for the evolution of plant RNA viruses.


Plant Methods ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Decai Tuo ◽  
Peng Zhou ◽  
Pu Yan ◽  
Hongguang Cui ◽  
Yang Liu ◽  
...  

Abstract Background Cassava is an important crop for food security and industry in the least-developed and developing countries. The completion of the cassava genome sequence and identification of large numbers of candidate genes by next-generation sequencing provide extensive resources for cassava molecular breeding and increase the need for rapid and efficient gene function analysis systems in cassava. Several plant virus-induced gene silencing (VIGS) systems have been developed as reverse genetic tools for rapid gene function analysis in cassava. However, these VIGS vectors could cause severe viral symptoms or inefficient gene silencing. Results In this study, we constructed agroinfection-compatible infectious cDNA clones of cassava common mosaic virus isolate CM (CsCMV-CM, genus Potexvirus, family Alphaflexiviridae) that causes systemic infection with mild symptoms in cassava. CsCMV-CM was then modified to a viral vector carrying the Nimble cloning frame, which facilitates the rapid and high-throughput cloning of silencing fragments into the viral genome. The CsCMV-based vector successfully silenced phytoene desaturase (PDS) and magnesium chelatase subunit I (ChlI) in different cassava varieties and Nicotiana benthamiana. The silencing of the ChlI gene could persist for more than two months. Conclusions This CsCMV-based VIGS system provides a new tool for rapid and efficient gene function studies in cassava.


Author(s):  
Sunny Dhir ◽  
Ashish Srivastava ◽  
Nobiyuki Yoshikawa ◽  
S. M. Paul Khurana

2006 ◽  
Vol 19 (11) ◽  
pp. 1229-1239 ◽  
Author(s):  
Xin Shun Ding ◽  
William L. Schneider ◽  
Srinivasa Rao Chaluvadi ◽  
M. A. Rouf Mian ◽  
Richard S. Nelson

Virus-induced gene silencing (VIGS) is used to analyze gene function in dicotyledonous plants but less so in monocotyledonous plants (particularly rice and corn), partially due to the limited number of virus expression vectors available. Here, we report the cloning and modification for VIGS of a virus from Festuca arundinacea Schreb. (tall fescue) that caused systemic mosaic symptoms on barley, rice, and a specific cultivar of maize (Va35) under greenhouse conditions. Through sequencing, the virus was determined to be a strain of Brome mosaic virus (BMV). The virus was named F-BMV (F for Festuca), and genetic determinants that controlled the systemic infection of rice were mapped to RNAs 1 and 2 of the tripartite genome. cDNA from RNA 3 of the Russian strain of BMV (R-BMV) was modified to accept inserts from foreign genes. Coinoculation of RNAs 1 and 2 from F-BMV and RNA 3 from R-BMV expressing a portion of a plant gene to leaves of barley, rice, and maize plants resulted in visual silencing-like phenotypes. The visual phenotypes were correlated with decreased target host transcript levels in the corresponding leaves. The VIGS visual phenotype varied from maintained during silencing of actin 1 transcript expression to transient with incomplete penetration through affected tissue during silencing of phytoene desaturase expression. F-BMV RNA 3 was modified to allow greater accumulation of virus while minimizing virus pathogenicity. The modified vector C-BMVA/G (C for chimeric) was shown to be useful for VIGS. These BMV vectors will be useful for analysis of gene function in rice and maize for which no VIGS system is reported.


2002 ◽  
Vol 15 (8) ◽  
pp. 799-807 ◽  
Author(s):  
V. Brault ◽  
S. Pfeffer ◽  
M. Erdinger ◽  
J. Mutterer ◽  
V. Ziegler-Graff

Transgenic Nicotiana benthamiana expressing the minor coat protein P74 of the phloem-limited Beet western yellows virus (BWYV) exhibited an unusual spatial pattern of post-transcriptional gene silencing (PTGS) when infected with BWYV or related viruses. Following infection, transgenic P74 and its mRNA accumulated to only low levels, 21 to 23 nucleotide RNAs homologous to the transgene appeared, and the transgene DNA underwent methylation. The infecting viral RNA, however, was not subject to significant silencing but multiplied readily and produced P74 in the phloem tissues, although the P74 encoded by the transgene disappeared from the phloem as well as the nonvascular tissues.


2021 ◽  
Vol 12 ◽  
Author(s):  
Neeti Sanan-Mishra ◽  
A. Abdul Kader Jailani ◽  
Bikash Mandal ◽  
Sunil K. Mukherjee

The major components of RNA silencing include both transitive and systemic small RNAs, which are technically called secondary sRNAs. Double-stranded RNAs trigger systemic silencing pathways to negatively regulate gene expression. The secondary siRNAs generated as a result of transitive silencing also play a substantial role in gene silencing especially in antiviral defense. In this review, we first describe the discovery and pathways of transitivity with emphasis on RNA-dependent RNA polymerases followed by description on the short range and systemic spread of silencing. We also provide an in-depth view on the various size classes of secondary siRNAs and their different roles in RNA silencing including their categorization based on their biogenesis. The other regulatory roles of secondary siRNAs in transgene silencing, virus-induced gene silencing, transitivity, and trans-species transfer have also been detailed. The possible implications and applications of systemic silencing and the different gene silencing tools developed are also described. The details on mobility and roles of secondary siRNAs derived from viral genome in plant defense against the respective viruses are presented. This entails the description of other compatible plant–virus interactions and the corresponding small RNAs that determine recovery from disease symptoms, exclusion of viruses from shoot meristems, and natural resistance. The last section presents an overview on the usefulness of RNA silencing for management of viral infections in crop plants.


2013 ◽  
Vol 40 (12) ◽  
pp. 1234 ◽  
Author(s):  
Stéphanie Pflieger ◽  
Manon M. S. Richard ◽  
Sophie Blanchet ◽  
Chouaib Meziadi ◽  
Valérie Geffroy

Legume species are among the most important crops worldwide. In recent years, six legume genomes have been completely sequenced, and there is now an urgent need for reverse-genetics tools to validate genes affecting yield and product quality. As most legumes are recalcitrant to stable genetic transformation, virus-induced gene silencing (VIGS) appears to be a powerful alternative technology for determining the function of unknown genes. VIGS technology is based on the property of plant viruses to trigger a defence mechanism related to post-transcriptional gene silencing (PTGS). Infection by a recombinant virus carrying a fragment of a plant target gene will induce homology-dependent silencing of the endogenous target gene. Several VIGS systems have been developed for legume species since 2004, including those based on Bean pod mottle virus, Pea early browning virus, and Apple latent spherical virus, and used in reverse-genetics studies of a wide variety of plant biological processes. In this work, we give an overview of the VIGS systems available for legumes, and present their successful applications in functional genomics studies. We also discuss the limitations of these VIGS systems and the future challenges to be faced in order to use VIGS to its full potential in legume species.


2003 ◽  
Vol 77 (1) ◽  
pp. 511-522 ◽  
Author(s):  
Feng Qu ◽  
Tao Ren ◽  
T. Jack Morris

ABSTRACT Posttranscriptional gene silencing (PTGS), or RNA silencing, is a sequence-specific RNA degradation process that targets foreign RNA, including viral and transposon RNA for destruction. Several RNA plant viruses have been shown to encode suppressors of PTGS in order to survive this host defense. We report here that the coat protein (CP) of Turnip crinkle virus (TCV) strongly suppresses PTGS. The Agrobacterium infiltration system was used to demonstrate that TCV CP suppressed the local PTGS as strongly as several previously reported virus-coded suppressors and that the action of TCV CP eliminated the small interfering RNAs associated with PTGS. We have also shown that the TCV CP must be present at the time of silencing initiation to be an effective suppressor. TCV CP was able to suppress PTGS induced by sense, antisense, and double-stranded RNAs, and it prevented systemic silencing. These data suggest that TCV CP functions to suppress RNA silencing at an early initiation step, likely by interfering the function of the Dicer-like RNase in plants.


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