Geminiviruses, The Plant Viruses with Single-Stranded DNA Genomes

ABSTRACT Replication initiation of nanoviruses, plant viruses with a multipartite circular single-stranded DNA genome, is triggered by the master Rep (M-Rep) protein. To enable the study of interactions between M-Rep and viral or host factors involved in replication, we designed oligohistidine-tagged variants of the nanovirus Faba bean necrotic yellows virus (FBNYV) M-Rep protein that allow affinity purification of enzymatically active M-Rep from plant tissue. The tagged M-Rep protein was able to initiate replication of its cognate and other FBNYV DNAs in Nicotiana benthamiana leaf disks and plants. The replicon encoding the tagged M-Rep protein multiplied and moved systemically in FBNYV-infected Vicia faba plants and was transmitted by the aphid vector of the virus. Using the tagged M-Rep protein, we demonstrated the in planta interaction between wild-type M-Rep and its tagged counterpart. Such a tagged and fully functional replication initiator protein will have bearings on the isolation of protein complexes from plants.

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Plant viruses with circular single-stranded DNA

Nature ◽

10.1038/270760a0 ◽

1977 ◽

Vol 270 (5639) ◽

pp. 760-762 ◽

Cited By ~ 113

Author(s):

B. D. HARRISON ◽

H. BARKER ◽

K. R. BOCK ◽

E. J. GUTHRIE ◽

GINA MEREDITH ◽

...

Keyword(s):

Plant Viruses ◽

Single Stranded Dna

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Insect Transmission of Plant Single-Stranded DNA Viruses

Annual Review of Entomology ◽

10.1146/annurev-ento-060920-094531 ◽

2021 ◽

Vol 66 (1) ◽

pp. 389-405

Author(s):

Xiao-Wei Wang ◽

Stéphane Blanc

Keyword(s):

Natural Infection ◽

Plant Viruses ◽

Virus Vector ◽

Insect Vector ◽

Insect Vectors ◽

Virus Species ◽

Ssdna Virus ◽

Plant Interactions ◽

Single Stranded Dna ◽

Ssdna Viruses

Of the approximately 1,200 plant virus species that have been described to date, nearly one-third are single-stranded DNA (ssDNA) viruses, and all are transmitted by insect vectors. However, most studies of vector transmission of plant viruses have focused on RNA viruses. All known plant ssDNA viruses belong to two economically important families, Geminiviridae and Nanoviridae, and in recent years, there have been increased efforts to understand whether they have evolved similar relationships with their respective insect vectors. This review describes the current understanding of ssDNA virus–vector interactions, including how these viruses cross insect vector cellular barriers, the responses of vectors to virus circulation, the possible existence of viral replication within insect vectors, and the three-way virus–vector–plant interactions. Despite recent breakthroughs in our understanding of these viruses, many aspects of plant ssDNA virus transmission remain elusive. More effort is needed to identify insect proteins that mediate the transmission of plant ssDNA viruses and to understand the complex virus–insect–plant three-way interactions in the field during natural infection.

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A Phage Single-Stranded DNA (ssDNA) Binding Protein Complements ssDNA Accumulation of a Geminivirus and Interferes with Viral Movement

Journal of Virology ◽

10.1128/jvi.73.2.1609-1616.1999 ◽

1999 ◽

Vol 73 (2) ◽

pp. 1609-1616 ◽

Cited By ~ 27

Author(s):

Malla Padidam ◽

Roger N. Beachy ◽

Claude M. Fauquet

Keyword(s):

Binding Protein ◽

Systemic Infection ◽

Plant Viruses ◽

Wild Type Virus ◽

Wild Type ◽

Direct Role ◽

Single Stranded Dna ◽

Ssdna Binding ◽

Ssdna Binding Protein ◽

Tomato Leaf Curl

ABSTRACT Geminiviruses are plant viruses with circular single-stranded DNA (ssDNA) genomes encapsidated in double icosahedral particles. Tomato leaf curl geminivirus (ToLCV) requires coat protein (CP) for the accumulation of ssDNA in protoplasts and in plants but not for systemic infection and symptom development in plants. In the absence of CP, infected protoplasts accumulate reduced levels of ssDNA and increased amounts of double-stranded DNA (dsDNA), compared to accumulation in the presence of wild-type virus. To determine whether the gene 5 protein (g5p), a ssDNA binding protein from Escherichia coli phage M13, could restore the accumulation of ssDNA, ToLCV that lacked the CP gene was modified to express g5p or g5p fused to the N-terminal 66 amino acids of CP (CP66:6G:g5). The modified viruses led to the accumulation of wild-type levels of ssDNA and high levels of dsDNA. The accumulation of ssDNA was apparently due to stable binding of g5p to viral ssDNA. The high levels of dsDNA accumulation during infections with the modified viruses suggested a direct role for CP in viral DNA replication. ToLCV that produced the CP66:6G:g5 protein did not spread efficiently in Nicotiana benthamiana plants, and inoculated plants developed only very mild symptoms. In infected protoplasts, the CP66:6G:g5 protein was immunolocalized to nuclei. We propose that the fusion protein interferes with the function of the BV1 movement protein and thereby prevents spread of the infection.

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Effects of an alphasatellite on life cycle of the nanovirus Faba bean necrotic yellows virus

Journal of Virology ◽

10.1128/jvi.01388-21 ◽

2021 ◽

Author(s):

Mahsa Mansourpour ◽

Romain Gallet ◽

Alireza Abbasi ◽

Stephane Blanc ◽

Akbar Dizadji ◽

...

Keyword(s):

Host Plant ◽

Faba Bean ◽

Acyrthosiphon Pisum ◽

Subterranean Clover ◽

Plant Viruses ◽

Single Stranded Dna ◽

Virus Load ◽

Aphid Vector ◽

The Impact ◽

Viral Accumulation

Nanoviruses are plant viruses with a multipartite single-stranded DNA (ssDNA) genome. Alphasatellites are commonly associated with nanovirus infections, but their putative impact on their helper viruses is unknown. In this study, we investigated the role of subterranean clover stunt alphasatellite 1 (hereafter named SCSA 1) on various important traits of faba bean necrotic yellows virus (FBNYV) in its host plant Vicia faba and aphid vector Acyrthosiphon pisum , including disease symptoms, viral accumulation and transmission. The results indicate that SCSA 1 does not affect the symptom severity nor the overall FBNYV accumulation in V. faba, but changes the relative amounts of its different genomic segments. Moreover, the association of SCSA 1 with FBNYV increases the rate of plant-to-plant transmission by a process seemingly unrelated to simple increase of the viral accumulation in the vector. These results represent the first study on the impact of an alphasatellite on the biology of its helper nanovirus. They suggest that SCSA 1 may benefit FBNYV, but the genericity of this conclusion is discussed and questioned. Importance Alphasatellites are circular single stranded DNA molecules frequently found in association with natural isolates of nanoviruses and some geminiviruse, the two ssDNA plant infecting virus families. While the implications of alphasatellite presence in geminivirus infections are relatively well documented, comparable studies on alphasatellites associated with nanoviruses are not available. Here we confirm that subterranean clover stunt alphasatellite 1 affects different traits of its helper nanovirus, faba bean necrotic yellows virus, both in the host plant and aphid vector. We show that the frequencies of the virus segments change in the presence of alphasatellite, in both plant and vector. We also confirm that while within-plant virus load and symptom are not affected by alphasatellite, the presence of alphasatellite decreases within-aphid virus load, but significantly increases virus transmission rate, so may confer a possible evolutionary advantage for the helper virus.

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A Single Rep Protein Initiates Replication of Multiple Genome Components of Faba Bean Necrotic Yellows Virus, a Single-Stranded DNA Virus of Plants

Journal of Virology ◽

10.1128/jvi.73.12.10173-10182.1999 ◽

1999 ◽

Vol 73 (12) ◽

pp. 10173-10182 ◽

Cited By ~ 58

Author(s):

Tatiana Timchenko ◽

Françoise de Kouchkovsky ◽

Lina Katul ◽

Chantal David ◽

Heinrich Josef Vetten ◽

...

Keyword(s):

Faba Bean ◽

Dna Cleavage ◽

Plant Viruses ◽

Site Directed Mutagenesis ◽

Nucleoside Triphosphate ◽

Dna Virus ◽

Single Stranded Dna ◽

Rep Protein ◽

Rep Proteins

ABSTRACT Faba bean necrotic yellows virus (FBNYV) belongs to the nanoviruses, plant viruses whose genome consists of multiple circular single-stranded DNA components. Eleven distinct DNAs, 5 of which encode different replication initiator (Rep) proteins, have been identified in two FBNYV isolates. Origin-specific DNA cleavage and nucleotidyl transfer activities were shown for Rep1 and Rep2 proteins in vitro, and their essential tyrosine residues that catalyze these reactions were identified by site-directed mutagenesis. In addition, we showed that Rep1 and Rep2 proteins hydrolyze ATP, and by changing the key lysine residue in the proteins’ nucleoside triphosphate binding sites, demonstrated that this ATPase activity is essential for multiplication of virus DNA in vivo. Each of the five FBNYV Rep proteins initiated replication of the DNA molecule by which it was encoded, but only Rep2 was able to initiate replication of all the six other genome components. Furthermore, of the fiverep components, only the Rep2-encoding DNA was always detected in 55 FBNYV samples from eight countries. These data provide experimental evidence for a master replication protein encoded by a multicomponent single-stranded DNA virus.

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Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100072782 ◽

1973 ◽

Vol 31 ◽

pp. 468-469

Author(s):

N.C. Lyon ◽

W. C. Mueller

Keyword(s):

Electron Microscopy ◽

Acetic Acid ◽

Nitric Acid ◽

Oxalic Acid ◽

Light Microscopy ◽

Epidermal Cell ◽

Cell Walls ◽

Plant Viruses ◽

Plant Leaves ◽

Thin Sections

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.

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Solid-phase immunoelectron microscopy for rapid diagnosis of enteroviruses

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100111240 ◽

1984 ◽

Vol 42 ◽

pp. 226-227 ◽

Cited By ~ 1

Author(s):

K. Pegg-Feige ◽

F. W. Doane

Keyword(s):

Electron Microscopy ◽

Cell Culture ◽

Immunoelectron Microscopy ◽

Detection Method ◽

Solid Phase ◽

Protein A ◽

Plant Viruses ◽

Rapid Diagnosis ◽

Virus Diagnosis ◽

Antiviral Antibody

Immunoelectron microscopy (IEM) applied to rapid virus diagnosis offers a more sensitive detection method than direct electron microscopy (DEM), and can also be used to serotype viruses. One of several IEM techniques is that introduced by Derrick in 1972, in which antiviral antibody is attached to the support film of an EM specimen grid. Originally developed for plant viruses, it has recently been applied to several animal viruses, especially rotaviruses. We have investigated the use of this solid phase IEM technique (SPIEM) in detecting and identifying enteroviruses (in the form of crude cell culture isolates), and have compared it with a modified “SPIEM-SPA” method in which grids are coated with protein A from Staphylococcus aureus prior to exposure to antiserum.

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A Sensitive On-Grid Immunoelectron Microscopic Procedure for Diagnosis of Rotavirus Infection

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s143192760000221x ◽

1980 ◽

Vol 38 ◽

pp. 506-507

Author(s):

M. F. Miller ◽

A. R. Rubenstein

Keyword(s):

Electron Microscopy ◽

Specific Antibody ◽

Immune Complexes ◽

Acute Gastroenteritis ◽

Plant Viruses ◽

Aggregation Process ◽

Microscopic Technique ◽

Fecal Material ◽

Present Communication ◽

Number Of Particles

Studies of rotavirus particles in humans, monkeys and various non-primates with acute gastroenteritis have involved detection of virus in fecal material by electron microscopy. The EM techniques most commonly employed have been the conventional negative staining (Fig. 1) and immune aggregation (Fig. 2) procedures. Both methods are somewhat insensitive and can most reliably be applied to samples containing large quantities of virus either naturaLly or as a result of concentration by ultracentrifugation. The formation of immune complexes by specific antibody in the immune aggregation procedures confirms the rotavirus diagnosis, but the number of particles per given microscope field is effectively reduced by the aggregation process. In the present communication, we describe use of an on-grid immunoelectron microscopic technique in which rotavirus particles are mounted onto microscope grids that were pre-coated with specific antibody. The technique is a modification of a method originalLy introduced by Derrick (1) for studies of plant viruses.

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