Serotypic variation in turnip mosaic virus

A panel of 30 monoclonal antibodies (MAbs) was produced against four isolates of turnip mosaic virus (TuMV). The panel was tested in plate-trapped antigen ELISA tests against 41 TuMV isolates (with different host and geographical origins and of differing pathotypes). The antibodies were also tested against four other potyviruses (bean common mosaic virus, bean common mosaic necrosis virus, lettuce mosaic virus and zucchini yellow mosaic virus). The reactions were assessed quantitatively (using multivariate analysis) and qualitatively (using the standard deviation obtained against healthy leaf material). The MAbs recognized 16–17 TuMV epitopes that were not present in the other potyviruses and a further two potyvirus epitopes. The isolates were grouped into three serotypes. Only one isolate did not fit this grouping. The classification of seven isolates in coat protein amino acid sequence homology groups correlated with serotypes. There was no correlation between serotype and pathotype, or between reactions to individual MAbs and single lines. There was therefore no evidence that the epitopes recognized by the MAbs are elicitors for the resistance genes present in the Brassica napus lines. However, the sensitivity and specificity of the MAbs will be useful for both routine detection of TuMV and fundamental studies on plant–virus interactions.     

Variability among turnip mosaic potyvirus isolates

ABSTRACT Eight turnip mosaic potyvirus (TuMV) isolates from the Campania region of Italy were characterized. Experiments based on host range and symptomatology indicated that the isolates were biologically different. In addition, the isolates, with the exception of ITA1 and ITA3, were distinguished from each other by using a combination of monoclonal antibodies recognizing the coat protein. Single-strand conformation polymorphism (SSCP) analysis of the coat protein gene revealed that each isolate produced a specific SSCP profile, except for isolates ITA1 and ITA3. This study indicates that (i) even in a small geographical region, there is a great deal of variation in TuMV isolates; (ii) the use of a set of four differential hosts does not always specify the same pathotype in different environments; (iii) the TuMV isolates with the same pathotype on Brassica napus test lines can still differ in host range, symptoms, serology, and SSCP; and (iv) there was perfect correlation between the panel of antibodies and SSCP in differentiating among the isolates; ITA1 and ITA3 were indistinguishable by either assay.     

Serological variability among European isolates of radish mosaic virus

Serological variability of radish mosaic virus (RaMV) isolates from white mustard, winter turnip rape, Camelina sativa and Chinese cabbage, collected in the Czech Republic and Russia, was studied using antisera against the Czech isolate RaMV1. In contrast to previous studies, reasonable serological differences were found between isolates from different locations and hosts, and even between neighbouring mustard plants in the field. Serological variability of European isolates was confirmed in extended experiments involving an Italian isolate, the American Type Strain (ATS) and its homologous antiserum. The results indicate that, in Europe, RaMV isolates may occur which differ both serologically and in host plant response, but no typical strains can be defined with the methods and isolates employed so far. Camelina sativa is reported as a new host of the virus.     

Biological and molecular variation amongst Australian Turnip mosaic virus isolates

Turnip mosaic virus (TuMV) causes crop losses worldwide. Eight Australian TuMV isolates originally obtained from five different species in two plant families were inoculated to 14 plant species belonging to four families to compare their host reactions. They differed considerably in virulence in Brassicaceae crop species and virus indicator hosts belonging to three other families. The isolates infected most Brassica species inoculated, but not Raphanus sativus, usually causing systemic mosaic symptoms, so they resembled TuMV biological host type [B]. Whole genome sequences of seven of the Australian isolates were obtained and had lengths of 9834 nucleotides (nt). When they were compared with 37 non‐recombinant TuMV genomes from other continents and another whole genome from Australia, six of them formed an Australian group within the overall world‐B phylogenetic grouping, while the remaining new genome sequence and the additional whole genome from Australia were part of the basal‐B grouping. When the seven new Australian genomes and the additional whole genome from Australia were subjected to recombination analysis, six different recombination events were found. Six genomes contained one or two recombination events each, but one was non‐recombinant. The non‐recombinant isolate was in the Australian grouping within the overall world‐B group while the remaining recombinant isolates were in the basal‐B and world‐B phylogenetic groups.     

Molecular characterization and detection of European isolates of Soil-borne wheat mosaic virus

Sequencing of a recently identified isolate of Soil-borne wheat mosaic virus (SBWMV) from the UK confirmed its identity as a European strain of the species and provided further evidence for taxonomic divisions in the group. Two RT–PCR protocols were developed for the detection of all SBWMV strains and for the specific detection of the European SBWMV strain, and were tested successfully on 21 isolates of SBWMV from a range of countries. Both protocols worked well using either purified total RNA in one- or two-step RT-PCR, or immunocapture (IC) RT–PCR. The sensitivity of IC RT-PCR was 100 times greater than ELISA. Neither set of primers produced any PCR product with either Wheat spindle streak mosaic virus or Wheat yellow mosaic virus which are frequently associated with SBWMV, or with the related viruses Indian peanut clump virus , Potato mop-top virus , Beet soil-borne virus and Beet necrotic yellow vein virus . This new diagnostic protocol will improve disease management by enabling correct identification of the causal pathogen and earlier detection than is possible serologically.     

Purification and characterization of turnip mosaic virus helper component protein

ABSTRACT The helper component (HC) protein of turnip mosaic virus (TuMV) was concentrated by differential centrifugation followed by ammonium sulfate precipitation. The partially purified HC was then loaded onto a Ni(2+)-resin column that bound the HC; a histidine tag was not required for binding. The HC eluted from the column migrated as a band of about 50 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In its native state, the HC did not pass through an ultrafiltration membrane with a molecular mass cutoff of 100 kDa, which suggested that the HC is in a multimeric form when it is biologically active. The molecular mass of the multimeric form was determined by gel filtration to be approximately 145 kDa. Purified HC retained its activity for several months at -20 degrees C. Using a protein blotting-overlay protocol, purified HC interacted in vitro with an aphid-transmissible TuMV isolate, but not with a non-aphid-transmissible isolate.     

Further studies on turnip yellow mosaic tymovirus isolates from an endemic Australian Cardamine

Native and introduced species of Cardamine and other brassicas were collected from various parts of south-eastern Australia and tested for sap-transmitted viruses. Isolates of turnip yellow mosaic virus (TYMV-Cd) were obtained from a robust sward-forming (SF) species, C. lilacina , that is an endemic species and restricted to the high glacial cirques of the Kosciusko alpine area. At two sites (Blue Lake and Club Lake) 22% of the plants were infected. An undescribed species of flightless pill beetle, Pedilophorus (Byrrhidae), was found on the C. lilacina SF plants. They preferred feeding on leaf discs infected with TYMV-Cd rather than on virus-free leaf discs and transmitted the virus for 48 h to seedlings of C. lilacina SF (2.5%) or Chinese cabbage (10%).
The pattern of distribution of TYMV-Cd and its close association with Pedilophorus suggested that it is not a recent migrant to the area. The possible time of its arrival is discussed.
A carlavirus was isolated from up to 4% of three other native highland Cardamine species.     

Host range and some properties of Physalis mosaic virus,a new virus of the turnip yellow mosaic virus group

An apparently undescribed virus was isolated fromPhysalis subglabrata in Illinois, USA, and its properties were studied. The virus was namedPhysalis mosaic virus (PMV). It was readily transmitted by sap inoculation to 23 out of 34 Solanaceae tested, toChenopodium foetidum andSonchus oleraceus but not to 28 other non-solanaceous species inoculated. Purified preparations of PMV contained isometric particles of 27 nm in diameter, which sedimented as two components with sedimentation coefficients of 50 and 112 S. The 112 S component was infectious, the 52 S component was not. The virus contained 38% ribonucleic acid with a molar base content of G 14.4%, A 22.9%, C 37,2% and U 25.5%.Purified preparations were highly infectious; a concentration of about 6000 particles per ml was infectious on plants.PMV is a member of the Andean potato latent virus subgroup of the turnip yellow mosaic virus group. The virus was closely related to the viruses: Andean potato latent, belladonna mottle, dulcamara mottle and egg-plant mosaic.Samenvatting Een nog niet eerder beschreven virus, dat in de staat Illinois (V.S. van Amerika) opPhysalis subglabrata was gevonden, werd in Wageningen bestudeerd. Het virus dat Physalis mosaic virus (PMV) (in het Nederlands:Physalis-mozaïekvirus) werd genoemd, kon met sap worden overgebracht.BehalveChenopodium foetidum enSonchus oleraceus bleken ook 23 van de 34 getoetste soorten uit de familie Solanaceae vatbaar voor dit virus te zijn. Gezuiverde virus preparaten bevatten isometrische deeltjes met een diameter van 27 nm (Fig. 2) Het virus bestaat uit twee deeltjes met sedimentatie-coëfficiënten van 112 en 50 S. Het 112 S deeltje bleek infectieus te zijn, het andere niet. Op grond van de sedimentatiecoëfficiënten kan worden berekend dat het 112 S deeltje 38% nucleïnezuur bevat. Voor de basenverhouding in het nucleïnezuur werd 22,9% adenine, 14,4% guanine, 37,2% cytosine en 25,5% uracil gevonden (Tabel 1). Het hoge gehalte van cytosine kwam ook tot uiting in de U.V. absorptiekromme van het virus en het nucleïnezuur (Fig. 1). Het gezuiverde virus bleek zeer infectieus te zijn; 6000 deeltjes/ml waren in staat een plant van de soortNicotiana clevelandii ziek te maken.Op grond van serologisch onderzoek kon het virus tot de turnip yellow mosaic virus groep worden gerekend. Het vertoonde serologische verwantschap met de Andean potato latent virus (APLV) subgroep (Tabel 2). In premunitieproeven bood het slechts een geringe bescherming tegen APLV en dulcamara mottle virus. Het omgekeerde werd eveneens geconstateerd. De leden van de APLV-subgroep kunnen op grond van hun waardplantenreeks van elkaar onderscheiden worden (Tabel 3).     

Changes in the glucosinolate content of oilseed rape plants following infection with turnip mosaic virus

Low and high glucosinolate cultivars of oilseed rape were analysed for variation in both individual and total glucosinolate content up to 27 days after inoculation with turnip mosaic virus. Both infected and control plants of the two cultivars differed in the concentration of aliphatic, aromatic and indole glucosinolates. The biggest differences in glucosinolate content between the cultivars were found in the aliphatic and aromatic glucosinolate groups. Infected plants of the high glucosinolate cultivar, Solida, possessed lower amounts of glucosinolates, than did healthy control plants. Similar results were obtained with a low glucosinolate cultivar, S1. No significant difference was found between the two cultivars in resistance to turnip mosaic virus, using qualitative and quantitative ELISA to determine virus content in their tissues.     

Advances and prospects in potato virology with special reference to virus resistance

Knowledge of the nucleotide sequences in the genomic nucleic acid of several potato viruses has enabled the open reading frames to be identified. These open reading frames are expressed by a variety of strategies, to produce proteins with functions in virus nucleic acid replication, virus particle production, cell-to-cell transport of virus and virus transmission by vectors. The activity of such proteins depends on their interactions with other viral or non-viral materials.Several other biological properties of plant viruses can also be related to individual viral gene products. For example, in plants co-infected with a specific pair of unrelated viruses, one virus can benefit from an ability to use the gene product of the second virus in replication, cell-to-cell transport or transmission by vectors. Similarly, different host resistance genes are targeted against viral replicase, movement protein or coat protein. Thus it is becoming possible to relate gene-for-gene (or more accurately, viral gene domain-host gene) interactions to events at the molecular level. Genetically engineered resistance to plant viruses likewise can be targeted against individual viral genes, and probably also against viral regulatory sequences. Such transgenic resistance seems likely to be as durable as conventional host resistance but durability should be improved by producing plants with combinations of resistances of different kinds, either conventional or genetically engineered, or both.     

Pepino mosaic virus isolates and differential symptomatology in tomato

Based on a survey conducted in commercial tomato production in Belgium in 2006, four Pepino mosaic virus (PepMV) isolates that differed in symptom expression in the crop of origin were selected for greenhouse trials. The selected isolates were inoculated onto tomato plants grown in four separate plastic tunnels. PepMV symptom development was assessed regularly and extensive sampling followed by ELISA analyses, genotyping and sequencing was performed to study viral presence and variation in PepMV sequences throughout the trial period. Two isolates (EU-mild and CH2-mild) that were selected based on mild symptom expression in the crop of origin caused only mild symptoms in the trial, while two other isolates (CH2-aggressive and EU + CH2) that were selected for severe symptom display, caused considerably more severe symptoms. Sequence homology between CH2-mild and CH2-aggressive was as high as 99·4%. Results of this study show that differential symptom expression can, at least partially, be attributed to the PepMV isolate, which may be related to minor differences at the nucleotide level between isolates.     

Cassava virus diseases and their control with special reference to southern Tanzania

Cassava is a major smallholder crop in much of Africa where it is attacked by two main virus diseases. African cassava mosaic disease (ACMD) occurs almost everywhere that the crop is grown causing severe losses in some countries. Cassava brown streak disease (CBSD) is of more restricted distribution being prevalent mainly on the east African coast and shores of Lake Malawi. Although both diseases have been known for many decades and much is known about ACMD, the aetiology and epidemiology of CBSD remain poorly understood. Control measures for African cassava mosaic virus (ACMV) have been recommended and in some cases implemented in a number of countries. Resistant varieties have been developed and national research programmes and international agencies are supporting phytosanitation programmes, based mainly on the distribution of ACMV-free planting material. It may be possible to use the same control measures against CBSD but the lack of basic information on the disease and difficulties of disease diagnosis are obstacles to the design of control strategies. ACMD is found in most areas where CBSD occurs and control measures must con sider the disease complex. This paper reviews the current knowledge about the two diseases in the context of possible integrated control     

Serological relationship of some European,American, and Canadian isolates of the white clover mosaic virus

Summary By means of the exchange of antisera a qualitative relationship could be established among a Dutch, some American, a Canadian and a German isolate of the white clover mosaic virus (fig. 1). An exact comparison of two isolates, viz. the Dutch W.K.V. and the American W.C.M.V. (ofBancroft), with a number of different antisera (table 1), and in a cross-absorption test (table 2), revealed no quantitative differences between these isolates. For such quantitative tests the exchange of virus isolates is inevitable.Samenvatting Door middel van de uitwisseling van antisera kon een kwalitatieve verwantschap worden aangetoond tussen een Nederlandse, enige Amerikaanse, een Canadese en een Duitse isolatie van het witte-klavermozaïekvirus. Een nauwkeurige vergelijking van twee isolaties, te weten het Nederlandse W.K.V. en het Amerikaanse W.C.M.V. (vanBancroft), met behulp van een aantal verschillende antisera (tabel 1) en in een proef, waarbij de antisera met wederzijdse virussen werden verzadigd (tabel 2), bracht geen kwantitatieve verschillen (stam-verschillen) aan het licht. Voor dergelijke kwantitatieve proeven is de uitwisseling van virusisolaties onvermijdelijk.Journal Paper No. 1559 of the Purdue University Agricultural Experiment Station.     

Characterization of Apple mosaic virus isolates detected in hazelnut in Poland

Journal of Plant Diseases and Protection - Apple mosaic virus (ApMV) infects over 65 plants species of Rosaceae family including hazelnut. The virus causes chlorotic or yellow patterns, rings and...     

Characterization of two distinct Polish isolates of Pepino mosaic virus

In Poland in 2002 and 2005 two different isolates of Pepino mosaic virus signed PepMV-SW and PepMV-PK were obtained. Both isolates were compared on the basis of their symptomatology on a series of plant species. In addition, the isolates were characterized by the nucleotide sequence analysis of the triple gene block, coat protein and a part of the polymerase genes. The studies showed that the Polish isolates differ from each other and belong to two strains. PepMV-SW was highly similar to European isolates, showing extensive sequence identity, ca. 99%. Pairwise comparisons of PepMV-PK with other PepMV isolates from the GenBank database showed that the highest nucleotide sequence identity was with two isolates: Ch2 from Chile and US2 from the USA.     

A viral disease of broad bean caused by a non-aphid-transmissible strain of turnip mosaic virus

A viral disease of broad bean ( Vicia faba ) was observed in Jiangsu, Zhejiang and Sichuan Province, the People's Republic of China. Its typical symptom on infected leaves was a white mottle, and, rarely, red necrotic lesions on several broad bean cultivars. A non-aphid-transmissible strain of turnip mosaic virus (TuMV) was identified as the causal agent of the disease on the basis of biological properties, particle morphology, seed and aphid transmission and serological tests. The virus could not be transmitted by aphids in the non-persistent manner.     

Electron microscope observations on the structure of the protein shell of turnip yellow mosaic virus

High resolution and high magnification electron micrographs of turnip yellow mosaic virus particles prepared by the negative staining procedure and the rotation technique are presented. Excellent agreement is found between these micrographs and a rhombic triacontahedron model with 32 subunits arranged in an icosahedral pattern with 532 symmetry. The protein shell of the virus is constructed of 32 morphological subunits. A discussion and interpretation of the electron microscope observations and the physico-chemical data is provided. All the evidence so far is strongly suggestive of 180 structural units representing possibly the total number of peptides in the virus protein shell. Some of the artifacts of the roration technique are also discussed.