Replication of Tobamovirus RNA

Ishibashi, Kazuhiro; Ishikawa, Masayuki

doi:10.1146/annurev-phyto-080615-100217

Cited by 69 publications

(53 citation statements)

References 145 publications

(163 reference statements)

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“…JAX1 inhibits de novo viral RNA synthesis when added at early times of PVX propagation. After the translation of RdRp, plant viruses are supposed to assemble viral RdRp, viral RNAs, and possible host factors to form a premature VRC and then target it to the appropriate membrane structure to form the VRC (42)(43)(44). Therefore, we next analyzed the effect of JAX1 on viral replication by use of BYLS30 (BYL supernatant after centrifugation at 30,000 ϫ g), in which the premature form of VRC just before association with membranes is accumulated (29).…”

Section: Resultsmentioning

confidence: 99%

The Plant Noncanonical Antiviral Resistance Protein JAX1 Inhibits Potexviral Replication by Targeting the Viral RNA-Dependent RNA Polymerase

Yoshida

Shiraishi

Hagiwara‐Komoda

et al. 2019

J Virol

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Understanding the innate immune mechanisms of plants is necessary for the breeding of disease-resistant lines. Previously, we identified the antiviral resistance gene JAX1 from Arabidopsis thaliana, which inhibits infection by potexviruses. JAX1 encodes a unique jacalin-type lectin protein. In this study, we analyzed the molecular mechanisms of JAX1-mediated resistance. JAX1 restricted the multiplication of a potexviral replicon lacking movement-associated proteins, suggesting inhibition of viral replication. Therefore, we developed an in vitro potato virus X (PVX) translation/replication system using vacuole- and nucleus-free lysates from tobacco protoplasts, and we revealed that JAX1 inhibits viral RNA synthesis but not the translation of the viral RNA-dependent RNA polymerase (RdRp). JAX1 did not affect the replication of a resistance-breaking mutant of PVX. Blue native polyacrylamide gel electrophoresis of fractions separated by sucrose gradient sedimentation showed that PVX RdRp constituted the high-molecular-weight complex that seems to be crucial for viral replication. JAX1 was detected in this complex of the wild-type PVX replicon but not in that of the resistance-breaking mutant. In addition, JAX1 interacted with the RdRp of the wild-type virus but not with that of a virus with a point mutation at the resistance-breaking residue. These results suggest that JAX1 targets RdRp to inhibit potexviral replication. IMPORTANCE Resistance genes play a crucial role in plant antiviral innate immunity. The roles of conventional nucleotide-binding leucine-rich repeat (NLR) proteins and the associated defense pathways have long been studied. In contrast, recently discovered resistance genes that do not encode NLR proteins (non-NLR resistance genes) have not been investigated extensively. Here we report that the non-NLR resistance factor JAX1, a unique jacalin-type lectin protein, inhibits de novo potexviral RNA synthesis by targeting the huge complex of viral replicase. This is unlike other known antiviral resistance mechanisms. Molecular elucidation of the target in lectin-type protein-mediated antiviral immunity will enhance our understanding of the non-NLR-mediated plant resistance system.

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Section: Resultsmentioning

confidence: 99%

The Plant Noncanonical Antiviral Resistance Protein JAX1 Inhibits Potexviral Replication by Targeting the Viral RNA-Dependent RNA Polymerase

Yoshida

Shiraishi

Hagiwara‐Komoda

et al. 2019

J Virol

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“…Tobamovirus RNA replication occurs via several steps: (a) synthesis of viral replication proteins by translation of the genomic RNA; (b) translation-coupled binding of the replication proteins to a 5′-terminal region of the genomic RNA; (c) recruitment of the genomic RNA by replication proteins onto membranes and formation of a complex with host proteins TOM1 and ARL8; (d) synthesis of complementary (negative-strand) RNA in the complex; and (e) synthesis of progeny genomic RNA [ 4 ].…”

Section: Replicationmentioning

confidence: 99%

ICTV Virus Taxonomy Profile: Virgaviridae

Adams¹,

Adkins

Bragard

et al. 2017

Journal of General Virology

157

100

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The family Virgaviridae is a family of plant viruses with rod-shaped virions, a ssRNA genome with a 3′-terminal tRNA-like structure and a replication protein typical of alpha-like viruses. Differences in the number of genome components, genome organization and the mode of transmission provide the basis for genus demarcation. Tobacco mosaic virus (genus Tobamovirus) was the first virus to be discovered (in 1886); it is present in high concentrations in infected plants, is extremely stable and has been extensively studied. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Virgaviridae, which is available at www.ictv.global/report/virgaviridae.

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“…The genome encodes four ORFs. ORF1 and ORF2, separated by a leaky stop codon, encode the 126 and 183 kDa replicase protein complex (recently reviewed in [21]). ORF3 encodes the 30 kDa movement protein (MP), and ORF4 encodes the 17.5 kDa coat protein (CP).…”

Section: Resistance-breaking Tobamovirusesmentioning

confidence: 99%

Seed Transmission of Tobamoviruses: Aspects of Global Disease Distribution

Dombrovsky¹,

Smith²

2017

Advances in Seed Biology

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Global seed trade contributed to development and improvement of world agriculture. An adverse effect of global seed trade is reflected in disease outbreaks in new growing areas, countries, and continents. Among the seed-borne viruses, Tobamovirus species are currently considered a peril for crop production around the world. The unique tobamoviral particles confer stability to the RNA genome and preserve their infectivity for years. High titer of Tobamovirus species accumulates in reproductive organs leading to viral particles adsorbed to seed coat, which potentially establish a primary infectious source. Tobamovirus-contaminated seeds show very low virus transmission in grow-out experiments as detected by enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR) analysis. Interestingly, in situ immunofluorescence analysis of Cucumber green mottle mosaic virus (CGMMV) reveals that the perisperm-endosperm envelope (PEE) is contaminated as well by the Tobamovirus. Indeed, chemical seed disinfection treatments that affect primarily the seed coat surface are efficient for several Tobamovirus species but apparently do not prevent seed transmission of CGMMV to occur. Tobamovirus infection of the seed internal layers, which rarely includes the embryo, may partially follow the direct invasion pathway of Potyviruses such as Pea seed-borne mosaic virus (PSbMV) to pea embryo.

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Replication of Tobamovirus RNA

Cited by 69 publications

References 145 publications

The Plant Noncanonical Antiviral Resistance Protein JAX1 Inhibits Potexviral Replication by Targeting the Viral RNA-Dependent RNA Polymerase

The Plant Noncanonical Antiviral Resistance Protein JAX1 Inhibits Potexviral Replication by Targeting the Viral RNA-Dependent RNA Polymerase

ICTV Virus Taxonomy Profile: Virgaviridae

Seed Transmission of Tobamoviruses: Aspects of Global Disease Distribution

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