Secoviridae: a proposed family of plant viruses within the order Picornavirales that combines the families Sequiviridae and Comoviridae, the unassigned genera Cheravirus and Sadwavirus, and the proposed genus Torradovirus

The order Picornavirales includes several plant viruses that are currently classified into the families Comoviridae (genera Comovirus, Fabavirus and Nepovirus) and Sequiviridae (genera Sequivirus and Waikavirus) and into the unassigned genera Cheravirus and Sadwavirus. These viruses share properties in common with other picornavirales (particle structure, positive-strand RNA genome with a polyprotein expression strategy, a common replication block including type III helicase, a 3C-like cysteine proteinase and type I RNA-dependent RNA polymerase). However, they also share unique properties that distinguish them from other picornavirales. They infect plants and use specialized proteins or protein domains to move through their host. In phylogenetic analysis based on their replication proteins, these viruses form a separate distinct lineage within the picornavirales branch. To recognize these common properties at the taxonomic level, we propose to create a new family termed “Secoviridae” to include the genera Comovirus, Fabavirus, Nepovirus, Cheravirus, Sadwavirus, Sequivirus and Waikavirus. Two newly discovered plant viruses share common properties with members of the proposed family Secoviridae but have distinct specific genomic organizations. In phylogenetic reconstructions, they form a separate sub-branch within the Secoviridae lineage. We propose to create a new genus termed Torradovirus (type species, Tomato torrado virus) and to assign this genus to the proposed family Secoviridae

Differential transmission of cherry rosette nepovirus by populations of Longidorus arthensis (Nematoda : Longidoridae) with a description of the association of the virus with the odontostyle of its vector

#Longidorus arthensis provenant de la rhizosphère de cerisiers à Maiberg, Baselland, après contact avec le nepovirus de la rosette du cerisier (CRV) ne transmet pas le virus, tandis que des spécimens provenant de la rhizosphère de cerisiers infestés par le CRV à Talmatte, Arth et à Rossberg, Steinerberg, le transmettent. De faibles différences morphométriques ont été relevées entre les nématodes du Baselland et ceux de la région de l'Arth, mais elles sont considérées comme intraspécifiques et non interspécifiques. L'examen en microscopie électronique de fine sections de spécimens femelles ayant transmis le CRV révèle la présence de quelques particules de virus seulement adsorbées à la surface de la lumière de l'odontostyle tandis que nombre de particules sont adsorbées, fréquemment en plusieurs couches, à la surface du fourreau-guide. Il est donc suggéré que les sites actifs de rétention des nepovirus transmis par les espèces de #Longidorus soient considérés comme étant la lumière de l'odontostyle et l'espace situé entre ce dernier et le fourreau-guide de l'odontostyle. (Résumé d'auteur

Complete nucleotide sequences and genome organization of a cherry isolate of cherry leaf roll virus

The complete nucleotide sequence of cherry leaf roll virus (CLRV, genus Nepovirus) from a naturally infected cherry tree (Prunus avium cv. Bing) in North America was determined. RNA1 and RNA2 consist of 7,893 and 6,492 nucleotides, respectively, plus a poly-(A) tail. Each RNA encodes a single potential open reading frame. The first 657 nucleotides of RNA1 and RNA2 are 99% identical and include the 5′-UTR and the first 214 deduced amino acids of the polyproteins following the first of two in-frame start codons. Phylogenetic analysis reveals close relationships between CLRV and members of subgroup C of the genus Nepovirus

Specificity, exclusivity and complementarity in the transmission of plant viruses by plant parasitic nematodes : an annotated terminology

Dix-huit espèces de nématodes phytoparasites appartenant aux genres #Longidorus, #Paralongidorus et #Xiphinema sont vectrices de douze nepovirus, tandis que treize espèces des genres #Paratrichodorus et #Trichodorus$ sont vectrices de trois tobravirus. Une caractéristique de ces nématodes vecteurs et de leurs associations avec les virus avait été rapidement reconnue lorsque des nepovirus sérologiquement distincts et des souches différentes de virus avaient été reconnus transmis par des espèces de Longidorides différentes, mais proches. Les virus avaient donc été considérés comme ayant des espèces vectrices "spécifiques", ce qui avait conduit à adopter une terminologie suivant laquelle les chercheurs faisaient référence à la "spécificité" de la transmission des virus par les nématodes vecteurs. En outre, la spécificité de la transmission avait été confirmée par des recherches ultérieures et démontrée s'étendre au niveau des populations des espèces vectrices et à celui de variants sérologiques mineurs des nepovirus. Il a été également démontré que ce phénomène s'applique aux tobravirus et à leurs vecteurs. Sont décrits dans cet article les mécanismes qui pourraient déterminer l'association entre les nématodes vecteurs et leurs virus. Sont également données et expliquées les définitions d'un certain nombre de termes et concepts utilisés lors des recherches sur les vections par les nématodes. (Résumé d'auteur

Subcellular localization and expression of bamboo mosaic virus satellite RNA-encoded protein

The satellite RNA of bamboo mosaic virus (satBaMV) has a single open reading frame encoding a non-structural protein, P20, which facilitates long-distance movement of satBaMV in BaMV and satBaMV co-infected plants. Immunohistochemistry and immunoelectron microscopy revealed that the P20 protein accumulated in the cytoplasm and nuclei in co-infected cells. P20 and the helper virus coat protein (CP) were highly similar in their subcellular localization, except that aggregates of BaMV virions were not labelled with anti-P20 serum. The BaMV CP protein was fairly abundant in mesophyll cells, whilst P20 was more frequently detected in mesophyll cells and vascular tissues. The expression kinetics of the P20 protein was similar to but slightly earlier than that of CP in co-infected Bambusa oldhamii protoplasts and Nicotiana benthamiana leaves. However, satBaMV-encoded protein levels declined rapidly in the late phase of co-infection. During co-infection, in addition to the intact P20, a low-molecular-mass polypeptide of 16 kDa was identified as a P20 C-terminally truncated product; the possible method of generation of the truncated protein is discussed

Tomato chocolàte virus: a new plant virus infecting tomato and a proposed member of the genus Torradovirus

A new virus was isolated from a tomato plant from Guatemala showing necrotic spots on the bases of the leaves and chocolate-brown patches on the fruits. Structural and molecular analysis showed the virus to be clearly related to but distinct from the recently described Tomato torrado virus (ToTV) and Tomato marchitez virus (ToMarV), both members of the genus Torradovirus. The name tomato chocolàte virus is proposed for this new torradovirus

Determinacion de generos de nematodos asociados a uva vinifera, en zonas regadas, productoras de vino en Chile.

Resumen (Spanish, English)71 p.Se tomaron muestras de suelo desde plantas con síntomas atribuibles a enfermedades virales, en las temporadas 1996/97 y 1997/98 realizando un muestreo dirigido a plantas de vid (Vitis vinifera), para determinar los géneros de nemátodos presentes. Este muestreo fue realizado en viñedos de la Zona Central de Chile, abarcando desde la V región (Valle de Casablanca) hasta la VII región (Valle del Maule). Se prospectaron un total de 31 viñedos, abarcando una superficie de 2.205 ha, colectando un total de 151 muestras de suelo utilizando dos métodos de extracción de nemátodos, el método del Embudo de Baermann y el de Tamizado de Cobb, en el Laboratorio de Fitopatología de la Universidad de Talca, VII región de Chile. Los géneros de nemátodos más importantes encontrados fueron Xiphinema index, Xiphinema americanum, Trichodorus sp y Meloidogyne sp. Los resultados de incidencia de los nemátodos fitopatógenos más importantes en plantas de vid, fueron obtenidos de acuerdo al número total de muestras colectadas, con un 37,8 % para Meloidogyne sp, luego tenemos a Xiphinema americanum con un 22,5 %, seguido por Xiphinema index con un 8,6% y por último encontramos a Trichodorus sp con un 1,3 %. Los resultados anteriores fueron complementados con los obtenidos en estudios paralelos, destinados a la determinación de nepovirus presentes en muestras de hojas y brotes, mediante la técnica serológia DAS - ELISA. Esto con la finalidad de asociar nemátodos transmisores de virus del género Xiphinema sp a los nepovirus TomRSV, TRSV, RRV, SLRSV, ArMV y GFLV. Encontrándose una asociación directa entre Xiphinema sp y la transmisión de los nepovirus ArMV, TRSV, TomRSV y RRV

Tomato ringspot nepovirus (ToRSV) in wild blackberry (Rubus fruticosus L.) in Hatay province of Turkey

During observations of virus-like symptoms in wild blackberry (Rubus fruticosus L., Rosaceae) some stunted plants growing in the border of stone-fruit orchards in Hatay were found showing severe yellow blotching and deformity of the leaves. Samples (shoots and leaves) were collected in September 2008 and May 2009 from wild blackberry plants growing at the border of apricot orchards and neighboring stone fruit nurseries in Hatay province in Eastern Mediterranean Region of Turkey. Each of 12 wild blackberry samples taken from 7 symptomatic and 5 symptomless plants were tested for virus by mechanical inoculation of sap to herbaceous plants. Sap was inoculated on Chenopodium amaranthicolor, C. quinoa, Cucumis sativus, Gombhrena globosa L., Nicotiana benthamiana, N. clevelandii, N. glutinosa, Phaseolus vulgaris L. and Vigna unguiculata L. Sap from six symptomatic plants induced symptoms of necrotic or chlorotic lesions, and ringspot on test plants. No symptoms were induced in the test plants inoculated by sap from symptomless blackberry plants. A sap-transmissible virus was obtained from all symptomatic plants and later identified as Tomato ringspot nepovirus (ToRSV) by enzyme-linked immunosorbent assay-ELISA. Thus, results of biological indexing were also confirmed by serological assays (ELISA). Cuttings of symptomatic plants were rooted in pots and kept in an insect-proof growing room for symptom observations and testing. Investigations on the other viruses in wild and cultivated Rubus spp. and its vector/s are still in progress. Further studies are necessary to investigate the distribution and natural transmission of the main virus diseases in cultivated Rubus spp. in particular because of the economic importance of Rubus cultivation and the recent increase in new commercial plantings in Hatay. This work represents the first report of ToRSV in wild blackberry (R. fruticosus) in Turkey. Keywords: Bioassay, Blackberry, ELISA, Rubus, ToRSV, viru