A novel nepovirus causing a chlorotic fleck disease on common bean (Phaseolus vulgaris L.).

Two common bean leaf samples from Ethiopia that had shown chlorotic fleck and veinal mosaic symptoms but tested ELISA-negative for known viruses were mechanically transmitted to herbaceous hosts to obtain virus isolates ET-773/4 and ET-779. Virus purification from Chenopodium quinoa systemically infected with ET-773/4 yielded icosahedral particles measuring ~ 30 nm in diameter and containing a single capsid protein of ~ 58 kDa, suggesting a nepovirus infection. Analysis of nucleotide sequences generated from RNA1 and RNA2 of the isolates indicated that they represent a distinct virus species in the genus Nepovirus.

Chickpea chlorotic stunt virus: a threat to cool-season food legumes.

Chickpea chlorotic stunt virus (CpCSV, genus Polerovirus, family Solemoviridae), first reported in Ethiopia in 2006, causes an economically important yellowing and stunting disease in legume crops such as chickpea, faba bean, field pea, and lentil in most production areas of North Africa and Central and West Asia. Disease epidemics have been reported in Ethiopia, Syria, and Tunisia. The virus is transmitted persistently by aphids of the species Aphis craccivora and Acyrthosiphon pisum and naturally infects several legume and non-legume hosts.

Taxonomy update for the family Alphasatellitidae: new subfamily, genera, and species.

Alphasatellites (family Alphasatellitidae) are circular, single-stranded DNA molecules (~1-1.4 kb) that encode a replication-associated protein and have commonly been associated with some members of the families Geminiviridae, Nanoviridae, and Metaxyviridae (recently established). Here, we provide a taxonomy update for the family Alphasatellitidae following the International Committee on Taxonomy of Viruses (ICTV) Ratification Vote held in March 2021.

ICTV Virus Taxonomy Profile: .

is a family of plant viruses (nanovirids) whose members have small isometric virions and multipartite, circular, single-stranded (css) DNA genomes. Each of the six (genus ) or eight (genus ) genomic DNAs is 0.9-1.

A divergent strain of melon chlorotic spot virus isolated from black medic (Medicago lupulina) in Austria.

A tenuivirus, referred to here as JKI 29327, was isolated from a black medic (Medicago lupulina) plant collected in Austria. The virus was mechanically transmitted to Nicotiana benthamiana, M. lupulina, M.

Identification of a novel nanovirus in parsley.

Using next-generation sequencing to characterize agents associated with a severe stunting disease of parsley from Germany, we identified a hitherto undescribed virus. We sequenced total RNA and rolling-circle-amplified DNA from diseased plants. The genome sequence of the virus shows that it is a member of the genus Nanovirus, but it lacks DNA-U4.

Characterisation of a novel nucleorhabdovirus infecting alfalfa (Medicago sativa).

Background: Nucleorhabdoviruses possess bacilliform particles which contain a single-stranded negative-sense RNA genome. They replicate and mature in the nucleus of infected cells. Together with viruses of three other genera of the family Rhabdoviridae, they are known to infect plants and can be transmitted by arthropod vectors, during vegetative propagation, or by mechanical means.

Subterranean Clover Stunt Virus Revisited: Detection of Two Missing Genome Components.

Subterranean clover stunt virus (SCSV) is a type species of the genus in the family . It was the first single-stranded DNA plant virus with a multipartite genome, of which genomic DNA sequences had been determined. All nanoviruses have eight genome components except SCSV, for which homologs of two genome components present in all other nanovirus genomes, DNA-U2 and DNA-U4, were lacking.

Complete genome sequence and construction of an infectious full-length cDNA clone of celery latent virus - an unusual member of a putative new genus within the Potyviridae.

Celery latent virus (CeLV) is an incompletely described plant virus known to be sap and seed transmissible and to possess flexuous filamentous particles measuring about 900 nm in length, suggesting it as a possible member of the family Potyviridae. Here, an Italian isolate of CeLV was transmitted by sap to a number of host plants and shown to have a single-stranded and monopartite RNA genome being 11 519 nucleotides (nts) in size and possessing some unusual features. The RNA contains a large open reading frame (ORF) that is flanked by a short 5' untranslated region (UTR) of 13 nt and a 3' UTR consisting of 586 nt that is not polyadenylated.

Nanovirus DNA-N encodes a protein mandatory for aphid transmission.

Nanoviruses possess a multipartite single-stranded DNA genome and are naturally transmitted to plants by various aphid species in a circulative non-propagative manner. Using the cloned genomic DNAs of faba bean necrotic stunt virus (FBNSV) for reconstituting nanovirus infections we analyzed the necessity of different virus components for infection and transmission by aphids. We found that in the absence of DNA-U1 and DNA-U2 symptom severity decreased, and in the absence of DNA-U1 the transmission efficiency decreased.

Analysis of DNAs associated with coconut foliar decay disease implicates a unique single-stranded DNA virus representing a new taxon.

The unique ecology, pathology and undefined taxonomy of coconut foliar decay virus (CFDV), found associated with coconut foliar decay disease (CFD) in 1986, prompted analyses of old virus samples by modern methods. Rolling circle amplification and deep sequencing applied to nucleic acid extracts from virion preparations and CFD-affected palms identified twelve distinct circular DNAs, eleven of which had a size of about 1.3 kb and one of 641 nt.

Genome diversity and evidence of recombination and reassortment in nanoviruses from Europe.

The recent identification of a new nanovirus, pea necrotic yellow dwarf virus, from pea in Germany prompted us to survey wild and cultivated legumes for nanovirus infections in several European countries. This led to the identification of two new nanoviruses: black medic leaf roll virus (BMLRV) and pea yellow stunt virus (PYSV), each considered a putative new species. The complete genomes of a PYSV isolate from Austria and three BMLRV isolates from Austria, Azerbaijan and Sweden were sequenced.

Turnip mosaic potyvirus probably first spread to Eurasian brassica crops from wild orchids about 1000 years ago.

Turnip mosaic potyvirus (TuMV) is probably the most widespread and damaging virus that infects cultivated brassicas worldwide. Previous work has indicated that the virus originated in western Eurasia, with all of its closest relatives being viruses of monocotyledonous plants. Here we report that we have identified a sister lineage of TuMV-like potyviruses (TuMV-OM) from European orchids.

The complete genome sequences of a Peruvian and a Colombian isolate of Andean potato latent virus and partial sequences of further isolates suggest the existence of two distinct potato-infecting tymovirus species.

The complete genomic RNA sequences of the tymovirus isolates Hu and Col from potato which originally had been considered to be strains of the same virus species, i.e. Andean potato latent virus (APLV), were determined by siRNA sequencing and assembly, and found to share only c.

Virus species polemics: 14 senior virologists oppose a proposed change to the ICTV definition of virus species.

The Executive Committee of the International Committee on Taxonomy of Viruses (ICTV) has recently decided to modify the current definition of virus species (Code of Virus Classification and Nomenclature Rule 3.21) and will soon ask the full ICTV membership (189 voting members) to ratify the proposed controversial change. In this discussion paper, 14 senior virologists, including six Life members of the ICTV, compare the present and proposed new definition and recommend that the existing definition of virus species should be retained.

Viruses of asparagus.

The current knowledge on viruses infecting asparagus (Asparagus officinalis) is reviewed. Over half a century, nine virus species belonging to the genera Ilarvirus, Cucumovirus, Nepovirus, Tobamovirus, Potexvirus, and Potyvirus have been found in this crop. The potyvirus Asparagus virus 1 (AV1) and the ilarvirus Asparagus virus 2 (AV2) are widespread and negatively affect the economic life of asparagus crops reducing yield and increasing the susceptibility to biotic and abiotic stress.

Analysis of the tomato mild mottle virus genome indicates that it is the most divergent member of the genus Ipomovirus (family Potyviridae).

The complete genome of a tomato mild mottle virus (ToMMV) isolate was analysed, and some biological features were characterized. The ssRNA genome of ToMMV from Ethiopia encompasses 9283 nucleotides (excluding the 3' poly(A) tail) and encodes a polyprotein of 3011 amino acids. Phylogenetic and pairwise comparisons with other members of the family Potyviridae revealed that ToMMV is the most divergent member of the genus Ipomovirus, with a genome organization similar to that of members of the species Sweet potato mild mottle virus, the type species of the genus.

First Report of Beet mosaic virus Infecting Chickpea (Cicer arietinum) in Tunisia.

Chickpea plants with severe yellowing and tip wilting were observed in the Cap-Bon Region of Tunisia in 2006. The viral-like symptoms resulted in yield loss of approximately 25% in some fields. A total of 110 symptomatic chickpea plants was collected from nine chickpea fields and tested at the Virology Laboratory of ICARDA, Syria for eight legume viruses using tissue-blot immunoassay (TBIA) (3).

High variability and rapid evolution of a nanovirus.

Nanoviruses are multipartite single-stranded DNA (ssDNA) plant viruses that cause important diseases of leguminous crops and banana. Little has been known about the variability and molecular evolution of these viruses. Here we report on the variability of faba bean necrotic stunt virus (FBNSV), a nanovirus from Ethiopia.

Serological and Molecular Identification of Chickpea chlorotic stunt virus from Chickpea in Iran.

During a survey of chickpea (Cicer arietinum L.) crops in western Iran in July 2009, leaf samples from yellow and stunted plants were collected from fields in the provinces of Kermanshah (n = 30) and Lorestan (n = 16). Symptoms suggested infections by luteoviruses, such as viruses of the Beet western yellows virus (BWYV) subgroup (e.

First Report of a Nanovirus Disease of Pea in Germany.

During the growing season of 2009, a disease consisting of leaf rolling, top yellows, and plant stunting affected pea (Pisum sativum) in fields near Aschersleben, Saxony-Anhalt, Germany. Samples from symptomatic plants collected in July 2009 were analyzed at the JKI in Braunschweig for infections by various legume viruses by ELISA, immunoelectron microscopy, and transmission assays by sap and aphids. Of 23 samples, 9 were shown to contain Pea enation mosaic virus and three samples each contained Bean leafroll virus and Soybean dwarf virus.

First Report of Carrot red leaf virus and Carrot mottle virus, Causal Agents of Carrot Motley Dwarf, in Carrot in Mauritius.

Carrot motley dwarf (CMD) affects carrot and other apiaceous plants by causing leaf yellowing or reddening as well as plant stunting and leads often to serious economic losses wherever these crops are grown (2). CMD has been reported from Australia, Europe, Japan, Israel, and North America and is known to result from a mixed infection by at least two viruses, the polerovirus, Carrot red leaf virus (CtRLV), and one of the umbraviruses, Carrot mottle virus (CMoV) or Carrot mottle mimic virus (CMoMV). The viruses are transmitted in a circulative persistent manner by aphid species (Cavariella spp.

Reconstitution of authentic nanovirus from multiple cloned DNAs.

We describe a new plant single-stranded DNA (ssDNA) virus, a nanovirus isolate originating from the faba bean in Ethiopia. We applied rolling circle amplification (RCA) to extensively copy the individual circular DNAs of the nanovirus genome. By sequence analyses of more than 208 individually cloned genome components, we obtained a representative sample of eight polymorphic swarms of circular DNAs, each about 1 kb in size.

Molecular characterization of a closterovirus from carrot and its identification as a German isolate of Carrot yellow leaf virus.

A high-molecular-weight dsRNA (approximately 15 kbp) was isolated from chlorotic leaves of a carrot plant and used for determining the entire nucleotide sequence of a closterovirus. The complete genome of this carrot closterovirus (CCV) was 16.4 kb in length and contained ten open reading frames (ORFs).