scholarly journals Differential Inductions of RNA Silencing among Encapsidated Double-Stranded RNA Mycoviruses in the White Root Rot Fungus Rosellinia necatrix

2016 ◽  
Vol 90 (12) ◽  
pp. 5677-5692 ◽  
Author(s):  
Hajime Yaegashi ◽  
Takeo Shimizu ◽  
Tsutae Ito ◽  
Satoko Kanematsu
Keyword(s):  
Rna Silencing ◽  
Defense Mechanism ◽  
Fluorescent Protein ◽  
Constitutive Expression ◽  
Phytopathogenic Fungus ◽  
Rosellinia Necatrix ◽  
Double Stranded Rna ◽  
Content Type ◽  
Molecular Features ◽  
Fungal Viruses

ABSTRACTRNA silencing acts as a defense mechanism against virus infection in a wide variety of organisms. Here, we investigated inductions of RNA silencing against encapsidated double-stranded RNA (dsRNA) fungal viruses (mycoviruses), including a partitivirus (RnPV1), a quadrivirus (RnQV1), a victorivirus (RnVV1), a mycoreovirus (RnMyRV3), and a megabirnavirus (RnMBV1) in the phytopathogenic fungusRosellinia necatrix. Expression profiling of RNA silencing-related genes revealed that a dicer-like gene, an Argonaute-like gene, and two RNA-dependent RNA polymerase genes were upregulated by RnMyRV3 or RnMBV1 infection but not by other virus infections or by constitutive expression of dsRNA inR. necatrix. Massive analysis of viral small RNAs (vsRNAs) from the five mycoviruses showed that 19- to 22-nucleotide (nt) vsRNAs were predominant; however, their ability to form duplexes with 3′ overhangs and the 5′ nucleotide preferences of vsRNAs differed among the five mycoviruses. The abundances of 19- to 22-nt vsRNAs from RnPV1, RnQV1, RnVV1, RnMyRV3, and RnMBV1 were 6.8%, 1.2%, 0.3%, 13.0%, and 24.9%, respectively. Importantly, the vsRNA abundances and accumulation levels of viral RNA were not always correlated, and the origins of the vsRNAs were distinguishable among the five mycoviruses. These data corroborated diverse interactions between encapsidated dsRNA mycoviruses and RNA silencing. Moreover, a green fluorescent protein (GFP)-based sensor assay inR. necatrixrevealed that RnMBV1 infection induced silencing of the target sensor gene (GFP gene and the partial RnMBV1 sequence), suggesting that vsRNAs from RnMBV1 activated the RNA-induced silencing complex. Overall, this study provides insights into RNA silencing against encapsidated dsRNA mycoviruses.IMPORTANCEEncapsidated dsRNA fungal viruses (mycoviruses) are believed to replicate inside their virions; therefore, there is a question of whether they induce RNA silencing. Here, we investigated inductions of RNA silencing against encapsidated dsRNA mycoviruses (a partitivirus, a quadrivirus, a victorivirus, a mycoreovirus, and a megabirnavirus) inRosellinia necatrix. We revealed upregulation of RNA silencing-related genes inR. necatrixinfected with a mycoreovirus or a megabirnavirus but not with other viruses, which was consistent with the relatively high abundances of vsRNAs from the two mycoviruses. We also showed common and different molecular features and origins of the vsRNAs from the five mycoviruses. Furthermore, we demonstrated the activation of RNA-induced silencing complex by mycoviruses inR. necatrix. Taken together, our data provide insights into an RNA silencing pathway against encapsidated dsRNA mycoviruses which is differentially induced among encapsidated dsRNA mycoviruses; that is, diverse replication strategies exist among encapsidated dsRNA mycoviruses.

scholarly journals Hypovirus Papain-Like Protease p29 Suppresses RNA Silencing in the Natural Fungal Host and in a Heterologous Plant System

2006 ◽  
Vol 5 (6) ◽  
pp. 896-904 ◽  
Author(s):  
Gerrit C. Segers ◽  
Rene van Wezel ◽  
Xuemei Zhang ◽  
Yiguo Hong ◽  
Donald L. Nuss
Keyword(s):  
Rna Silencing ◽  
Defense Mechanism ◽  
Fluorescent Protein ◽  
Cryphonectria Parasitica ◽  
Fungal Host ◽  
Chestnut Blight Fungus ◽  
Systemic Spread ◽  
Green Fluorescent ◽  
Fungal Viruses ◽  
Suppressor Of Rna Silencing

ABSTRACT Virulence-attenuating hypoviruses of the species Cryphonectria hypovirus 1 (CHV1) encode a papain-like protease, p29, that shares similarities with the potyvirus-encoded suppressor of RNA silencing HC-Pro. We now report that hypovirus CHV1-EP713-encoded p29 can suppress RNA silencing in the natural host, the chestnut blight fungus Cryphonectria parasitica. Hairpin RNA-triggered silencing was suppressed in C. parasitica strains expressing p29, and transformation of a transgenic green fluorescent protein (GFP)-silenced strain with p29 resulted in an increased number of transformants with elevated GFP expression levels. The CHV1-EP713 p29 protein was also shown to suppress both virus-induced and agroinfiltration-induced RNA silencing and systemic spread of silencing in GFP-expressing transgenic Nicotiana benthamiana line 16c plants. The demonstration that a mycovirus encodes a suppressor of RNA silencing provides circumstantial evidence that RNA silencing in fungi may serve as an antiviral defense mechanism. The observation that a phylogenetically conserved protein of related plant and fungal viruses functions as a suppressor of RNA silencing in both fungi and plants indicates a level of conservation of the mechanisms underlying RNA silencing in these two groups of organisms.

scholarly journals Potentiation of Mycovirus Transmission by Zinc Compounds via Attenuation of Heterogenic Incompatibility in Rosellinia necatrix

2013 ◽  
Vol 79 (12) ◽  
pp. 3684-3691 ◽  
Author(s):  
Kenichi Ikeda ◽  
Kanako Inoue ◽  
Chiaki Kida ◽  
Takahiro Uwamori ◽  
Atsuko Sasaki ◽  
...  
Keyword(s):  
Defense Mechanism ◽  
Fluorescent Protein ◽  
Rosellinia Necatrix ◽  
Cell Wall Modification ◽  
Content Type ◽  
Zinc Compounds ◽  
Cell Death Pathway ◽  
Hyphal Anastomosis ◽  
Green Fluorescent ◽  
Incompatibility Reaction

ABSTRACTHeterogenic incompatibility is considered a defense mechanism against deleterious intruders such as mycovirus.Rosellinia necatrixshows strong heterogenic incompatibility. In the heterogenic incompatibility reaction, the approaching hyphae hardly anastomosed, a distinctive barrage line formed, and green fluorescent protein (GFP)-labeled hyphae quickly lost their fluorescence when encountering incompatible hyphae. In this study, transmission of a hypovirulence-conferring mycovirus to strains with different genetic backgrounds was attempted. Various chemical reagents considered to affect the programmed cell death pathway or cell wall modification were examined. Treatment with zinc compounds was shown to aid in transmission of mycoviruses to strains with different genetic backgrounds. In incompatible pairings, treatment with zinc compounds accelerated hyphal anastomosis; moreover, cytosolic GFP was transmitted to the newly joined hyphae. These results suggest that zinc compounds not only increase hyphal anastomosis but also attenuate heterogenic incompatibility.

Molecular features of RNA silencing against phloem-restricted polerovirus TuYV enable amplification of silencing signal from host transcripts

2021 ◽  
Author(s):  
Marion Clavel ◽  
Esther Lechner ◽  
Marco Incarbone ◽  
Timothée Vincent ◽  
Valérie Cognat ◽  
...  
Keyword(s):  
Rna Silencing ◽  
Host Response ◽  
Defense Mechanism ◽  
Molecular Level ◽  
Substantial Reduction ◽  
Molecular Features ◽  
Turnip Yellows Virus ◽  
Model Plant Arabidopsis Thaliana ◽  
Plant Arabidopsis Thaliana

In plants and some animal lineages, RNA silencing is an efficient and adaptable defense mechanism against viruses. To counter it, viruses encode suppressor proteins that interfere with RNA silencing. Phloem-restricted viruses are spreading at an alarming rate and cause substantial reduction of crop yield, but how they interact with their hosts at the molecular level is still insufficiently understood. Here, we investigate the antiviral response against phloem-restricted turnip yellows virus (TuYV) in the model plant Arabidopsis thaliana. Using a combination of genetics, deep sequencing, and mechanical vasculature enrichment, we show that the main axis of silencing active against TuYV involves 22-nt vsiRNA production by DCL2, and their preferential loading into AGO1. Unexpectedly, and despite the viral encoded VSR P0 previously shown to mediate degradation of AGO proteins, vascular AGO1 undergoes specific post-translational stabilization during TuYV infection. We also identify vascular novel secondary siRNA produced from conserved plant transcripts and initiated by DCL2-processed AGO1-loaded vsiRNA, supporting a viral strategy to modulate host response. Collectively, our work uncovers the complexity of antiviral RNA silencing against phloem-restricted TuYV and prompts a re-assessment of the role of its suppressor of silencing P0 during genuine infection

scholarly journals Antiviral Defense Involves AGO4 in an Arabidopsis–Potexvirus Interaction

2016 ◽  
Vol 29 (11) ◽  
pp. 878-888 ◽  
Author(s):  
Chantal Brosseau ◽  
Mohamed El Oirdi ◽  
Ayooluwa Adurogbangba ◽  
Xiaofang Ma ◽  
Peter Moffett
Keyword(s):  
Gene Expression ◽  
Nuclear Localization ◽  
Rna Silencing ◽  
Defense Mechanism ◽  
Rna Viruses ◽  
Antiviral Defense ◽  
Double Stranded Rna ◽  
Micro Rnas ◽  
Plantago Asiatica ◽  
Antiviral Activities

In plants, RNA silencing regulates gene expression through the action of Dicer-like (DCL) and Argonaute (AGO) proteins via micro RNAs and RNA-dependent DNA methylation (RdDM). In addition, RNA silencing functions as an antiviral defense mechanism by targeting virus-derived double-stranded RNA. Plants encode multiple AGO proteins with specialized functions, including AGO4-like proteins that affect RdDM and AGO2, AGO5, and AGO1, which have antiviral activities. Here, we show that AGO4 is also required for defense against the potexvirus Plantago asiatica mosaic virus (PlAMV), most likely independent of RdDM components such as DCL3, Pol IV, and Pol V. Transient assays showed that AGO4 has direct antiviral activity on PlAMV and, unlike RdDM, this activity does not require nuclear localization of AGO4. Furthermore, although PlAMV infection causes a decrease in AGO4 expression, PlAMV causes a change in AGO4 localization from a largely nuclear to a largely cytoplasmic distribution. These results indicate an important role for AGO4 in targeting plant RNA viruses as well as demonstrating novel mechanisms of regulation of and by AGO4, independent of its canonical role in regulating gene expression by RdDM.

scholarly journals Apple chlorotic leaf spot virus 50 kDa movement protein acts as a suppressor of systemic silencing without interfering with local silencing in Nicotiana benthamiana

2007 ◽  
Vol 88 (1) ◽  
pp. 316-324 ◽  
Author(s):  
Hajime Yaegashi ◽  
Tsubasa Takahashi ◽  
Masamichi Isogai ◽  
Takashi Kobori ◽  
Satoshi Ohki ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Nicotiana Benthamiana ◽  
Rna Silencing ◽  
Fluorescent Protein ◽  
Movement Protein ◽  
Silencing Suppressor ◽  
Spot Virus ◽  
Double Stranded Rna ◽  
Chlorotic Leaf ◽  
Green Fluorescent

Apple chlorotic leaf spot virus (ACLSV) is the type species of the genus Trichovirus and its single-stranded, plus-sense RNA genome encodes a 216 kDa protein (P216) involved in replication, a 50 kDa movement protein (P50) and a 21 kDa coat protein (CP). In this study, it was investigated whether these proteins might have RNA silencing-suppressor activities by Agrobacterium-mediated transient assay in the green fluorescent protein-expressing Nicotiana benthamiana line 16c. The results indicated that none of these proteins could suppress local silencing in infiltrated leaves. However, systemic silencing in upper leaves induced by both single- and double-stranded RNA could be suppressed by P50, but not by a frame-shift mutant of P50, P216 or CP. Moreover, when P50 was expressed separately from where silencing signals were generated in a leaf, systemic silencing in upper leaves was inhibited. Collectively, our data indicate that P50 acts as a suppressor of systemic silencing without interfering with local silencing, probably by inhibiting the movement of silencing signals.

scholarly journals Heterodimers as the Structural Unit of the T=1 Capsid of the Fungal Double-Stranded RNA Rosellinia necatrix Quadrivirus 1

2016 ◽  
Vol 90 (24) ◽  
pp. 11220-11230 ◽  
Author(s):  
Daniel Luque ◽  
Carlos P. Mata ◽  
Fernando González-Camacho ◽  
José M. González ◽  
Josué Gómez-Blanco ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Sieves ◽  
Three Dimensional ◽  
Rosellinia Necatrix ◽  
Double Stranded Rna ◽  
Content Type ◽  
Cryo Electron Microscopy ◽  
Wide Range ◽  
The Family ◽  
Dsrna Viruses

ABSTRACTMost double-stranded RNA (dsRNA) viruses are transcribed and replicated in a specialized icosahedral capsid with a T=1 lattice consisting of 60 asymmetric capsid protein (CP) dimers. These capsids help to organize the viral genome and replicative complex(es). They also act as molecular sieves that isolate the virus genome from host defense mechanisms and allow the passage of nucleotides and viral transcripts. Rosellinia necatrix quadrivirus 1 (RnQV1), the type species of the familyQuadriviridae, is a dsRNA fungal virus with a multipartite genome consisting of four monocistronic segments (segments 1 to 4). dsRNA-2 and dsRNA-4 encode two CPs (P2 and P4, respectively), which coassemble into ∼450-Å-diameter capsids. We used three-dimensional cryo-electron microscopy combined with complementary biophysical techniques to determine the structures of RnQV1 virion strains W1075 and W1118. RnQV1 has a quadripartite genome, and the capsid is based on a single-shelled T=1 lattice built of P2-P4 dimers. Whereas the RnQV1-W1118 capsid is built of full-length CP, P2 and P4 of RnQV1-W1075 are cleaved into several polypeptides, maintaining the capsid structural organization. RnQV1 heterodimers have a quaternary organization similar to that of homodimers of reoviruses and other dsRNA mycoviruses. The RnQV1 capsid is the first T=1 capsid with a heterodimer as an asymmetric unit reported to date and follows the architectural principle for dsRNA viruses that a 120-subunit capsid is a conserved assembly that supports dsRNA replication and organization.IMPORTANCEGiven their importance to health, members of the familyReoviridaeare the basis of most structural and functional studies and provide much of our knowledge of dsRNA viruses. Analysis of bacterial, protozoal, and fungal dsRNA viruses has improved our understanding of their structure, function, and evolution, as well. Here, we studied a dsRNA virus that infects the fungusRosellinia necatrix, an ascomycete that is pathogenic to a wide range of plants. Using three-dimensional cryo-electron microscopy and analytical ultracentrifugation analysis, we determined the structure and stoichiometry of Rosellinia necatrix quadrivirus 1 (RnQV1). The RnQV1 capsid is a T=1 capsid with 60 heterodimers as the asymmetric units. The large amount of genetic information used by RnQV1 to construct a simple T=1 capsid is probably related to the numerous virus-host and virus-virus interactions that it must face in its life cycle, which lacks an extracellular phase.

scholarly journals Genome-Wide Transcriptional and Physiological Responses of Bradyrhizobium japonicum to Paraquat-Mediated Oxidative Stress

2011 ◽  
Vol 77 (11) ◽  
pp. 3633-3643 ◽  
Author(s):  
Andrew J. Donati ◽  
Jeong-Min Jeon ◽  
Dipen Sangurdekar ◽  
Jae-Seong So ◽  
Woo-Suk Chang
Keyword(s):  
Oxidative Stress ◽  
Stress Responses ◽  
Bradyrhizobium Japonicum ◽  
Defense Mechanism ◽  
Constitutive Expression ◽  
Soybean Plant ◽  
Ros Scavenging ◽  
Content Type ◽  
Genome Wide ◽  
Physiological Tests

ABSTRACTThe rhizobial bacteriumBradyrhizobium japonicumfunctions as a nitrogen-fixing symbiont of the soybean plant (Glycine max). Plants are capable of producing an oxidative burst, a rapid proliferation of reactive oxygen species (ROS), as a defense mechanism against pathogenic and symbiotic bacteria. Therefore,B. japonicummust be able to resist such a defense mechanism to initiate nodulation. In this study, paraquat, a known superoxide radical-inducing agent, was used to investigate this response. Genome-wide transcriptional profiles were created for both prolonged exposure (PE) and fulminant shock (FS) conditions. These profiles revealed that 190 and 86 genes were up- and downregulated for the former condition, and that 299 and 105 genes were up- and downregulated for the latter condition, respectively (>2.0-fold;P< 0.05). Many genes within putative operons for F0F1-ATP synthase, chemotaxis, transport, and ribosomal proteins were upregulated during PE. The transcriptional profile for the FS condition strangely resembled that of a bacteroid condition, including the FixK2transcription factor and most of its response elements. However, genes encoding canonical ROS scavenging enzymes, such as superoxide dismutase and catalase, were not detected, suggesting constitutive expression of those genes by endogenous ROS. Various physiological tests, including exopolysaccharide (EPS), cellular protein, and motility characterization, were performed to corroborate the gene expression data. The results suggest thatB. japonicumresponds to tolerable oxidative stress during PE through enhanced motility, increased translational activity, and EPS production, in addition to the expression of genes involved in global stress responses, such as chaperones and sigma factors.

scholarly journals A Novel Victorivirus from a Phytopathogenic Fungus, Rosellinia necatrix, Is Infectious as Particles and Targeted by RNA Silencing

2013 ◽  
Vol 87 (12) ◽  
pp. 6727-6738 ◽  
Author(s):  
S. Chiba ◽  
Y.-H. Lin ◽  
H. Kondo ◽  
S. Kanematsu ◽  
N. Suzuki
Keyword(s):  
Rna Silencing ◽  
Phytopathogenic Fungus ◽  
Rosellinia Necatrix

Novel, diverse RNA viruses from Mediterranean isolates of the phytopathogenic fungus,Rosellinia necatrix: insights into evolutionary biology of fungal viruses

2018 ◽  
Vol 20 (4) ◽  
pp. 1464-1483 ◽  
Author(s):  
Juan Manuel Arjona-Lopez ◽  
Paul Telengech ◽  
Atif Jamal ◽  
Sakae Hisano ◽  
Hideki Kondo ◽  
...  
Keyword(s):  
Evolutionary Biology ◽  
Rna Viruses ◽  
Phytopathogenic Fungus ◽  
Rosellinia Necatrix ◽  
Fungal Viruses

scholarly journals Novel Hypovirulence-Associated RNA Mycovirus in the Plant-Pathogenic Fungus Botrytis cinerea: Molecular and Biological Characterization

2015 ◽  
Vol 81 (7) ◽  
pp. 2299-2310 ◽  
Author(s):  
Lin Yu ◽  
Wen Sang ◽  
Ming-De Wu ◽  
Jing Zhang ◽  
Long Yang ◽  
...  
Keyword(s):  
Botrytis Cinerea ◽  
Fluorescent Protein ◽  
Rna Virus ◽  
Pathogenic Fungus ◽  
Ornamental Plants ◽  
Gray Mold ◽  
Open Reading Frames ◽  
Content Type ◽  
Molecular Features ◽  
Green Fluorescent

ABSTRACTBotrytis cinereais a pathogenic fungus causing gray mold on numerous economically important crops and ornamental plants. This study was conducted to characterize the biological and molecular features of a novel RNA mycovirus, Botrytis cinerea RNA virus 1 (BcRV1), in the hypovirulent strain BerBc-1 ofB. cinerea. The genome of BcRV1 is 8,952 bp long with two putative overlapped open reading frames (ORFs), ORF1 and ORF2, coding for a hypothetical polypeptide (P1) and RNA-dependent RNA polymerase (RdRp), respectively. A −1 frameshifting region (designated the KNOT element) containing a shifty heptamer, a heptanucleotide spacer, and an H-type pseudoknot was predicted in the junction region of ORF1 and ORF2. The −1 frameshifting role of the KNOT element was experimentally confirmed through determination of the production of the fusion protein red fluorescent protein (RFP)-green fluorescent protein (GFP) by the plasmid containing the constructdsRed-KNOT-eGFPinEscherichia coli. BcRV1 belongs to a taxonomically unassigned double-stranded RNA (dsRNA) mycovirus group. It is closely related to grapevine-associated totivirus 2 and Sclerotinia sclerotiorum nonsegmented virus L. BcRV1 in strain BerBc-1 was found capable of being transmitted vertically through macroconidia and horizontally to otherB. cinereastrains through hyphal contact. The presence of BcRV1 was found to be positively correlated with hypovirulence inB. cinerea, with the attenuation effects of BcRV1 on mycelial growth and pathogenicity being greatly affected by the accumulation level of BcRV1.

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