Bean Leafroll Virus Research Articles

Incidence and transmission of Faba bean necrotic yellows virus (FBNYV) in Spain

Information on the distribution of Faba bean necrotic yellows virus (FBNYV) in Spain was gathered by sampling different legume crops (faba bean "Muchamiel", forage faba bean, pea and chickpea) in four regions (Murcia, Andalucía, Castilla y León, and Extremadura). The virus was detected by TAS-ELISA in faba bean "Muchamiel" and peas only in the Murcia region. A portion of 272 bp within the C5 component of a FBNYV from Murcia was amplified by IC-PCR and directly sequenced. The Spanish FBNYV was 93.75% identical to two previously sequenced isolates of FBNYV from Syria and Egypt. Periodic samplings of faba bean "Muchamiel" over one growing season (Oct. 1999 to Jan. 2000) in Murcia provided no clear evidence of any spread of the disease either within or beyond the affected fields. Mixed infections of FBNYV and Tomato spotted wilt virus (TSWV), Bean leaf roll virus (BLRV) and Bean yellow mosaic virus (BYMV) were commonly observed. The necrotic symptoms developed on the leaf borders were more pronounced in these mixed infections. Transmission experiments using a Spanish isolate as inoculum source and the aphid species Acyrthosiphon pisum and Aphis craccivora showed that both are efficient FBNYV vectors. In these experiments, the faba bean cvs. "Aguadulce", "Muchamiel" and "Valenciana"were all susceptible to FBNYV.

A Survey of Viruses Affecting French bean (Phaseolus vulgaris) in Iran Includes a First Report of Southern bean mosaic virus and Bean pod mottle virus.

A survey was conducted from 2003 to 2004 to identify viruses infecting common bean (Phaseolus vulgaris L.) in different growing areas of East Azarbaejan Province of Iran. A total of 300 French bean samples with symptoms of viral infection (mosaic, vein clearing, leaf rolling, yellowing, and leaf distortion) were collected. The samples were tested for eight viruses using the tissue-blot immunoassay procedures (TBIA) (2) and double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) according to the manufacturer's instructions (DSMZ, Braun-schweig, Germany). ELISA tests for Alfalfa mosaic virus (AMV), Bean yellow mosaic virus (BYMV), Bean common mosaic virus (BCMV), Bean common mosaic necrosis virus (BCMNV), Cucumber mosaic virus (CMV), Bean leaf roll virus (BLRV), and Southern bean mosaic virus (SBMV) were used. In addition, antiserum was provided by S. A. Ghabrial (University of Kentucky, Lexington) to test for Bean pod mottle virus (BPMV). Serological tests showed that SBMV and BPMV were present in 12% (35 samples) and 5% (15 samples) of samples, respectively. BCMV, BCMNV, BYMV, BLRV, CMV, and AMV were more common and were detected in 155, 105, 80, 46, 30, and 10 samples of 300 samples, respectively. These six viruses were previously reported in other pulses and in French bean in Iran (1). The presence of SBMV and BPMV were verified in samples by transmission to French bean (Phaseolus vulgaris), cowpea (Vigna unguiculata), and soybean (Glycine max) indicator test plants (3,4). Inoculation with extracts from SBMV-positive plants produced systemic mottle and mosaic symptoms in soybean (cv. Gorgan-3) and French bean (cvs. Dubbele Witte and Cheete). In cowpea (cv. Mashad) and French bean (cv. Pinto), inoculation produced necrotic local lesions. Inoculation with extracts from BPMV-positive plants produced severe mosaic, leaf distortion, and puckering in soybean (cv. Gorgan-3) and French bean (cv. Ten-dergreen). No symptoms were observed in cowpea (cv. Mashad). Cvs. Pinto and Bountiful bean reacted with necrotic local lesions. All indicator test plants tested positive for the presence of SBMV or BPMV as expected using DAS-ELISA. To our knowledge, this is the first report of BPMV and SBMV naturally infecting French bean in Iran. These viruses can cause a serious problem to other leguminous crops grown in Iran.

Survey of viruses affecting legume crops in the Amhara and Oromia Regions of Ethiopia

Field surveys were undertaken to identify the viral diseases affecting lentil, faba bean, chickpea, pea, fenugreek and grass pea in two regions of Ethiopia. The surveys were conducted in the regions of Amhara (Gonder and Gojam administrative zones) and Oromia (Bale administrative zone) during the 2003/2004 and 2004/2005 growing seasons, respectively. The survey covered 138 randomly selected fields (48 faba bean, 10 pea, 38 grass pea, 34 chickpea, 8 lentil) in the Amhara region, and 51 legume fields (29 faba bean, 12 pea, 3 lentil, 5 fenugreek, 2 chickpea) in the Oromia region. Virus disease incidence was determined by laboratory testing of 100–200 randomly-collected samples from each field against the antisera of 12 legume viruses. Of the 189 fields surveyed, 121 and 7 had, at the time of the survey, a virus disease incidence of 1% or less and more than 6%, respectively, based on visual inspection in the field; later laboratory testing showed that the number of fields in these two categories was in fact 99 and 56, respectively. Serological tests indicated that the most important viruses in the Amhara region were Faba bean necrotic yellows virus (FBNYV), Bean yellow mosaic virus (BYMV), Pea seed-borne mosaic virus (PSbMV) and the luteoviruses [e.g. Beet western yellows virus (BWYV), Bean leaf roll virus (BLRV), Soybean dwarf virus (SbDV)]. By contrast, only FBNYV and the luteoviruses were detected in the Oromia region. Other viruses, such as Broad bean mottle virus (BBMV) and Alfalfa mosaic virus (AMV), were rarely detected in the Amhara region. This is the first report in Ethiopia of natural infection of faba bean, pea and fenugreek with SbDV, of fenugreek with BWYV, and of grass pea with BYMV, PSbMV and BWYV, and it is also the first recorded instance of BBMV infecting legume crops in Ethiopia.

Optimization of RT–PCR for the Detection of Bean leaf roll virus in Plant Hosts and Insect Vectors

AbstractThe detection of luteoviruses by reverse transcription polymerase chain reaction (RT–PCR) depends on the adequate quality and quantity of extracted viral nucleic acids. We have optimized the detection of Bean leaf roll virus (BLRV) using selective precipitation by LiCl of viral RNA from a small quantity of infected plant tissues and insect vectors. The optimal template for PCR was 15 μl of RT reaction mixture. BLRV was detected in different plant hosts and aphid vectors and Aphis fabae, previously considered to be a non‐vector of BLRV, was found to acquire the virus from infected plants.

Occurrence of virus infection in seed stocks and 3-year-old pastures of lucerne (Medicago sativa)

In tests on seed samples from 26 commercial seed stocks of lucerne (Medicago sativa) to be sown in south-western Australia in 2001, infection with Alfalfa mosaic virus (AMV) was found in 21 and Cucumber mosaic virus (CMV) in 3 of them. Bean yellow mosaic virus (BYMV) and Pea seed-borne mosaic virus (PSbMV) were not detected in any. Incidences of infection within individual affected seed samples were 0.1–4% (AMV) and 0.1–0.3% (CMV), and the infected seed stocks were from 3 (CMV) and at least 11 (AMV) different lucerne cultivars. In a survey of 31 three-year-old lucerne pastures in the same region in 2001, in randomly collected samples, AMV was found in 30 and luteovirus infection in 11 pastures. Pastures in high, medium, and low rainfall zones were all infected. Incidences of AMV within individual infected pastures were high, with 50–98% of plants infected in 20 of them and only 3 having <10% infection, but luteovirus incidences were only 1–5%. In addition to various cultivar mixtures, at least 8 (AMV) and 3 (luteoviruses) different individual lucerne cultivars were infected. When the species of luteovirus present were identified, they were Bean leaf roll virus, Beet western yellows virus ( = Turnip yellows virus), or Subterranean clover red leaf virus ( = Soybean dwarf virus). CMV and legume-infecting potyviruses (BYMV, PSbMV, and Clover yellow vein virus) were not detected in any of the lucerne samples. Acyrthosiphon kondoi infestation was common in the samples collected, and A. pisum and Aphis craccivora were also found. Widespread infection in lucerne stands, and their frequent colonisation by aphid vectors, are cause for concern not only because of virus-induced production losses in lucerne itself but also because they provide virus infection reservoirs for spread to nearby grain legume crops and annual legume pastures.

A Survey of Viruses Affecting Faba Bean (Vicia faba) in Tunisia Includes First Record of Soybean dwarf virus.

A survey was conducted in April 2003 to identify viruses infecting faba bean (Vicia faba L.) in six regions (Beja, Bizerte, Cap-bon, Le Kef, Siliana, and Zaghouan) in Tunisia. A total of 292 faba bean samples with symptoms of viral infection (leaf rolling, yellowing, and mosaic) were collected. The samples were tested at the virology laboratory of the International Center for Agricultural Research in the Dry Areas (ICARDA), Syria, for 11 viruses using the tissue-blot immunoassay procedure (3). Specific rabbit polyclonal antisera were used to test for Chickpea chlorotic dwarf virus (CpCDV) (provided by H. J. Vetten, BBA, Braunschweig, Germany), Alfalfa mosaic virus (AMV), Bean yellow mosaic virus (BYMV), Broad bean mottle virus (BBMV), Broad bean stain virus (BBSV), Cucumber mosaic virus (CMV), and Pea seedborne mosaic virus (PSbMV) (ICARDA, Aleppo, Syria). In addition, four specific monoclonal antibodies were used to detect Bean leaf roll virus (BLRV) (4B10) (2), Beet western yellows virus (BWYV) (ATCC PVAS-647; American Type Culture Collection, Manassas, VA), Faba bean necrotic yellows virus (FBNYV) (3-2E9) (1), and Soybean dwarf virus (SbDV) (ATCC PVAS-650). Serological tests showed that BBMV, a beetle-transmitted and seedborne virus identified in 23.3% (68 samples) of the samples tested, was the most common. BLRV, FBNYV, BWYV, BYMV, SbDV, and PSbMV were detected in 56, 33, 31, 10, 5, and 1 sample(s) of 292 samples tested, respectively. AMV, BBSV, CMV, and CpCDV were not detected in any samples tested. In Tunisia, BLRV, BWYV, BYMV, FBNYV, and PSbMV have previously been reported in faba bean (4), but to our knowledge, this is the first record of SbDV affecting faba bean in Tunisia, where it was detected in two fields in the Cap-bon Region. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by western blots, extracts from SbDV-infected plants were observed to contain 23-kDa structural proteins, which reacted strongly with SbDV monoclonal antibodies. Transmission tests showed that the samples, which reacted with SbDV monoclonal antibodies, were transmitted to faba bean plants by the pea aphid (Acyrthosiphon pisum Harris) in a persistent manner. To our knowledge, this is the first report of SbDV naturally infecting faba bean in Tunisia and it could cause a serious problem to other leguminous crops grown in Tunisia, such as French bean and peas, which are hosts for the virus.

First record of Chickpea chlorotic dwarf virus (CpCDV) affecting faba bean (Vicia faba) crops in Egypt

A field visit was conducted in March 2002 to identify viruses infecting the faba bean ( Vicia faba ) crop in four governorates (Fayoum, Beni Suef, El-Nobareia and Bihera) in Egypt. A total of 71 faba bean samples with symptoms of viral infection (leaf rolling, yellowing and mosaic) were collected. These were tested at the Virology Laboratory of ICARDA, Syria, for seven viruses using the tissue-blot immunoassay procedure (Makkouk & Comeau, 1994). Specific rabbit polyclonal antisera were used to test for Chickpea chlorotic dwarf virus (CpCDV, genus Mastrevirus , family Geminiviridae ; provided by H. J. Vetten, BBA, Braunschweig, Germany); for Broad bean stain virus (BBSV, genus Comovirus , family Comoviridae ); for Bean yellow mosaic virus (BYMV, genus Potyvirus , family Potyviridae ) and for Pea seed borne mosaic virus (PSbMV, genus Potyvirus , family Potyviridae ). In addition, three specific monoclonal antibodies were used to detect Faba bean necrotic yellows virus (FBNYV, genus Nanovirus , family Nanoviridae ) (Franz et al ., 1996); Bean leaf roll virus (BLRV, family Luteoviridae ) (4B10; Katul, 1992) and Beet western yellows virus (BWYV, genus Polerovirus , family Luteoviridae ) (ATCC PVAS-647; American Type Culture Collection, Manassas, VA, USA). Serological tests showed that BYMV, an aphid-transmitted and seedborne virus that was identified in 89% of samples tested, was the most common virus. In most of the fields surveyed, BYMV symptoms were noted to occur at high levels (80–100% infection). PSbMV was detected in nine samples (one from Fayoum and eight from Beni Suef); FBNYV was detected in 11 samples (all from Beni Suef). CpCDV, a leafhopper-transmitted virus, was, by contrast, detected in only two samples collected from the El-Nobareia governorate showing leaf rolling, yellowing and stunting. BWYV, BLRV and BBSV were not detected in any of the samples tested. In Egypt, FBNYV, BYMV and PSbMV have previously been reported in faba bean (Makkouk et al ., 1994), but this is the first record of CpCDV affecting faba bean in Egypt. CpCDV is the only member of the Geminivirus that is reported to naturally infect faba bean.

First report of Faba bean necrotic yellows virus (FBNYV) infecting chickpea (Cicer arietinum) and faba bean (Vicia faba) crops in Sudan

A total of 45 faba bean samples ( Vicia faba ) and 130 chickpea samples ( Cicer arietinum ) were collected from plants with symptoms that suggested a viral infection (leaf rolling, yellowing and stunting) during the period 1999– 2001 at the Shambat and Hudeiba Research Stations, Sudan. These samples were tested, using the tissue-blot immunoassay procedure (Makkouk & Comeau, 1994), at the Virology Laboratory of ICARDA, Syria. The antisera used included both monoclonal and polyclonal antibodies. The monoclonal antibodies were ATCC PVAS647 (American Type Culture Collection, Manassas, VA, USA), used to test for Beet western yellows virus (BWYV, genus Polerovirus , family Luteoviridae ); ATCC PVAS650, used to test for Soybean dwarf virus (SbDV, family Luteoviridae ); 4B10, used to test for Bean leaf roll virus (BLRV, family Luteoviridae ; Katul, 1992); and 3-2E9 and 2-5H9, used to test for Faba bean necrotic yellows virus (FBNYV, genus Nanovirus , family Nanoviridae ) – the latter monoclonal is FBNYV-specific (Franz et al ., 1996). A polyclonal antibody (provided by H.J. Vetten, BBA, Braunschweig, Germany) was used to test for Chickpea chlorotic dwarf virus (CpCDV, genus Mastrevirus , family Geminiviridae ). Laboratory tests showed that CpCDV, a leafhopper-transmitted virus, was the most abundant virus in chickpea; however, FBNYV, an aphid-transmitted virus, was the most common virus in faba bean samples. FBNYV has been reported to infect food legumes in many countries in western Asia and North Africa, and reaches epidemic levels in some countries, including Egypt (Makkouk et al ., 1994). CpCDV was detected in 77·0% of chickpea and 15·5% of faba bean samples tested, whereas FBNYV was detected in 95·5% of faba bean and 6·2% of chickpea samples tested. Only two chickpea samples tested positive for BWYV, while SbDV and BLRV were not detected in any of the samples. Based on the reaction with the FBNYV-specific monoclonal (2-5H9) and the characteristic symptoms of leaf rolling, stunting and yellowing of leaves, with necrosis of the leaf periphery in faba bean and yellowing and stunting in chickpea, this is the first record of FBNYV affecting faba bean and chickpea in Sudan.

Differentiation Among Bean Leafroll Virus Susceptible and Resistant Lentil and Faba Bean Genotypes on the Basis of Virus Movement and Multiplication

AbstractSystemic movement of Bean leafroll virus (BLRV) in susceptible and resistant lentil and faba bean genotypes was studied using plants grown in a plastic house. All the plants studied were inoculated with BLRV by viruliferous pea aphids (Acyrthosiphon pisum). Five plants/genotype of lentil and faba bean were harvested, respectively, at 3, 6, 9, 12 and 18 days and 1, 2, 3, 4 and 5 weeks after inoculation. Each plant was split into growing point, stem, stem base and root, and each was tested using tissue blot immunoassays (TBIA). Virus concentration in each section was estimated using a 0–3 score and a relative TBIA value was estimated accordingly for each genotype. In susceptible lentil genotypes (ILL 8063 and ILL 2581), BLRV was present in low concentrations in the growing point 3 days after inoculation and in high concentrations in all parts of the plant after 6 days. By contrast, the virus was not detected in the highly resistant genotype (ILL 74) until 18 days after inoculation. In the faba bean genotypes studied, BLRV was detected in high concentrations in all parts of the highly susceptible genotype (Fiord) 1 week after inoculation but only after 3 weeks in resistant genotypes (e.g. BPL 5274), but was not detected in the highly resistant genotypes (BPL 5278 and BPL 5279) 5 weeks after inoculation. The replication and systemic movement of BLRV was thus slower in resistant genotypes than in susceptible genotypes. Moreover, the use of TBIA scores clearly and easily differentiated resistant and susceptible genotypes. Our results suggest that BLRV movement and multiplication can be useful criteria when differentiating resistant from susceptible genotypes. In addition, undertaking the preliminary screening in a plastic house requires less space than direct planting in the field.

Low-cost paper can be used in tissue-blot immunoassay for detection of cereal and legume viruses

In an effort to reduce the cost of virus assays, different types of regular paper were evaluated as possible replacements for the commonly used nitrocellulose membrane (NCM) as the solid phase in the tissue-blot immunoassay (TBIA) used to detect Alfalfa mosaic virus, Bean yellow mosaic virus and Broad bean stain virus (BBSV) in faba bean tissue, and Barley yellow striate mosaic virus in barley tissue. Among the many types of paper evaluated, Hewlett-Packard (HP) non-glossy plotter paper proved to be adequate for detection of all the above viruses. After printing (blotting) of the samples to be tested and blocking with either 2% gelatin (for one hour at 37oC) or using 0.1% Roche blocking reagent (for one hour at room temperature), satisfactory results were produced. This paper could also be used to detect BBSV in groups consisting of 15 young lentil seedlings. HP non-glossy plotter paper was not as effective when testing for phloem-limited legume viruses such as Bean leaf roll virus (BLRV), Faba bean necrotic yellows virus (FBNYV) and Barley yellow dwarf virus (BYDV). White paper (manufactured by Soporcel, Portugal) was slightly more sensitive when used for BLRV and FBNYV detection in faba bean tissues and for BYDV in barley tissues. Since NCM represents 40–50% of the cost of test reagents, using ordinary paper reduced costs considerably.

Screening and selection of faba bean (Vicia faba L.) germplasm resistant to Bean leafroll virus

Three hundred and fifty-eight faba bean accessions, originating from 28 countries in 5 continents, were evaluated for their reaction to a Syrian isolate (SV64-95) of Bean leafroll virus (BLRV, family Luteoviridae). Selection for resistance was based on: (i) visual evaluation for symptom expression (disease severity); (ii) virus concentration in the plant tissues, based on the intensity of reaction in the tissue-blot immunoassay; and (iii) seed yield. A large variability in resistance to BLRV was found both between and within faba bean accessions. Progenies of single plants, selected for resistance under inbreeding conditions, were evaluated for another 2-year period. Repeated reselection of inoculated plants, in the absence of outcrossing, significantly increased the proportion of resistant plants. The most resistant selections were made from populations originating from Afghanistan, China, Colombia, Pakistan, Russia, Sudan, Switzerland, Tunisia, Turkey, and Yemen.

First record of Beet western yellows virus, Chickpea chlorotic dwarf virus and Faba bean necrotic yellows virus affecting faba bean (Vicia faba) crops in Iraq

A survey to identify virus diseases affecting faba bean(Vicia faba) in Iraq was conducted during April 2000.Around 4400 samples were collected from 36 faba beanfields distributed in five governorates (ten in Baghdad,nine in Al-Anbar, three in Diyala, five in At-Tamim andnine in Ninawa). These samples were tested for thepresence of 12 different viruses by tissue-blot immu-noassay (Lin et al., 1990), using a battery of polyclonaland monoclonal antibodies. Rabbit polyclonal antiseraspecific for Chickpea chlorotic dwarf virus (CCDV)(Horn et al., 1993); Broad bean true mosaic virus(BBTMV) (from H. Rohloff, BBA, Braunschweig,Germany); Broad bean wilt virus (BBWV); Pea enationmosaic virus (PEMV) (from IPO, Wageningen, theNetherlands); Alfalfa mosaic virus (AMV); Bean yellowmosaic virus (BYMV); Broad bean mottle virus(BBMV); Broad bean stain virus (BBSV); Cucumbermosaic virus (CMV); and Pea seed-borne mosaic virus(PSbMV) (from Virology Laboratory, ICARDA,Aleppo, Syria) were used, in addition to a monoclonalspecific for Faba bean necrotic yellows virus (FBNYV)(Franz et al., 1996) and a broad-spectrum legumeluteovirus monoclonal (5G4) (Katul, 1992). To identifyspecific luteoviruses, samples that tested positive usingmonoclonal 5G4 were tested against five furthermonoclonals: Beet western yellows virus (BWYV)(ATCC PVAS-647); Soybean dwarf virus (SbDV) (ATCCPVAS-650); Potato leaf roll virus (PLRV) (ATCC PVAS-649); and Bean leaf roll virus (BLRV) (4B10) and 6F9,which reacts with either BLRV or SbDV (Katul, 1992).BYMV was the most abundant virus in faba bean inIraq, identified in 68% of test samples. In 50% of thefields surveyed, BYMV was identified at extremely highlevels (80–100% infection). BWYV was detected in 135samples collected from 15 fields from all five governor-ates. Two fields in the Ninawa governorate were highlyinfected with BWYV (62 and 96%). CCDV wasdetected in eight samples collected from three fields(two in El-Anbar and one in Ninawa), and FBNYV wasdetected in seven samples collected from two fields inNinawa governorate.This is the first record of BWYV, CCDV and FBNYVaffecting faba bean in Iraq. Other viruses such as AMV,BBWVand CMV were detected in fewer than 1% of thesamples tested. BBMV, BBSV, BBTMV, PEMV andPSbMV were not detected in any of the samples.

Reduction of incidence of three persistently transmitted aphid-borne viruses affecting legume crops by seed-treatment with the insecticide imidacloprid (Gaucho ®)

The effectiveness of using seed treatment with imidacloprid (Gaucho ®) to reduce the incidence of Bean leaf roll virus (BLRV, family Luteoviridae), Faba bean necrotic yellows virus (FBNYV, genus Nanovirus) and Soybean dwarf virus (SbDV, family Luteoviridae) in faba bean and lentil was investigated, using artificial inoculation with an aphid vector, Acyrthosiphon pisum (Harris). Imidacloprid was applied as a seed dressing at the rate of 0.0, 0.35, 0.7, 1.4 and 2.8 g a.i./kg of seeds. Incidence of BLRV, FBNYV and SbDV in faba bean was reduced from 92, 28 and 98% in untreated plots to 23, 2 and 85% in plots treated with 1.4 g a.i./kg and 13, 1 and 85% in plots treated with 2.8 g a.i./kg, respectively. Moreover, the yield loss was reduced from 80, 37 and 56% in untreated plots to 14, 0 and 39% in plots treated with 1.4 g a.i./kg, and to 14, 0 and 34% in plots treated with 2.8 g a.i./kg, for the above three viruses, respectively. Results indicated that imidacloprid at 2.8 g a.i./kg reduced virus incidence in faba bean plants when they were inoculated with BLRV two months after sowing from 91.6% in untreated plots to 0%, but no effect was detected when virus inoculation was done three months after sowing. Moreover, imidacloprid seed treatment significantly improved lentil yields of moderately resistant and susceptible lentil genotypes, but had no effect on the yield of resistant genotypes. In addition, seed treatment was more effective in increasing seed yield of BLRV and FBNYV-inoculated plots compared to SbDV-inoculated plots. Based on these results, seed treatment with imidacloprid at 1.4 g a.i./kg of seeds can effectively reduce the incidence of two persistently transmitted aphid-borne viruses, BLRV and FBNYV, affecting faba bean and lentil crops.

Viral Diseases of Cultivated Legume and Cereal Crops in Tunisia

A survey to identify virus diseases affecting legume (chickpea, faba bean and lentil) and cereal (bread and durum wheat and barley) crops at different locations in Tunisia was conducted in April, 2000. Thirty-eight legume fields (34 faba bean, 3 chickpea and one lentil) and 43 cereal fields (21 durum wheat, 7 bread wheat and 15 barley) were randomly selected. The identity of the viruses and virus disease incidence was determined on 100-200 randomly collected samples and 20-25 symptomatic samples from each field by testing samples against antisera of 12 legume and 6 cereal viruses. In the faba bean fields, Broad bean mottle virus (BBMV) and Beet western yellows virus (BWYV) were the most common followed by Faba bean necrotic yellows virus (FBNYV). In cereal fields, Barley stripe mosaic virus (BSMV) was the most common followed by Barley yellow dwarf virus (BYDV) and Barley yellow striate mosaic virus (BYSMV). Two faba bean fields had a virus disease incidence of 21% or higher at the time of the survey and two cereal fields had a virus disease incidence of more than 6%. The highest incidences found were 24.5% (BWYV and/or FBNYV) in the Siliana region and 23% (BBMV and/or BWYV) in the Jendouba region, both in faba bean fields, and 10.5% (BSMV) in a barley field in the Cap-Bon region. Other viruses, such as Broad bean stain virus (BBSV), Bean leaf roll virus (BLRV) and Cucumber mosaic virus (CMV) in legumes, and Wheat dwarf virus (WDV) in cereals were rare.

First Report of Bean Leafroll Luteovirus Infecting Pea in Italy.

Approximately 5,000 ha of processing peas (Pisum sativum L) are cultivated annually in the Po River Valley of northern Italy. During the 1998 growing season, affected pea plants in this region were observed that exhibited mild chlorosis and mottling, leaf rolling, and stunting symptoms. High aphid populations and disease levels of nearly 100% were observed in susceptible varieties. Samples from affected fields were analyzed for the presence of bean leafroll virus (BLRV). Nonviruliferous pea aphids (Acyrthosiphon pisum Harris) received a 48-h acquisition access period on symptomatic leaves. Aphids were then transferred to Puget pea and Diana faba bean for a 72-h inoculation access period. Leaf samples were also macerated in 0.05 M potassium phosphate pH 7.4, and inoculated mechanically to pea, faba bean, chickpea (Cicer arietinum L.), Chenopodium quinoa Willd., and C. amaranticolor Coste & Reyn. Symptoms typical of those observed in the original field plants appeared 10 to 14 days after aphid transmissions in both pea and faba bean inoculated with pea aphids. No symptoms were observed in any of the hosts that were inoculated mechanically. Total nucleic acid extracts from the original pea samples, and from leaf tissue of pea and faba bean plants inoculated with aphids, served as templates in reverse-transcriptase polymerase chain reaction assays. Primers BLR-V157 and BLR-C546, which flanked a 400-bp fragment, were designed with available sequence data for the coat protein gene of BLRV (1). An amplification product of the expected size was generated from symptomatic plants but not from healthy controls. Sequence analysis of the cloned fragments revealed a 99% nucleic acid homology with the published sequence for BLRV and an isolate obtained from alfalfa in Washington State (R. Larsen, unpublished). This is the first report of BLRV in Italy. Reference: (1) B. Brill et al. Nucleic Acids Res. 18:5544, 1990.

Molecular evidence for the occurrence of beet western yellows virus on chickpea in Morocco

A luteovirus isolate infecting chickpea in Morocco was experimentally transmitted by Myzus persicae to Physalis floridana, on which it produced mild symptoms. When tested in western blots against antisera to known legume luteoviruses, this isolate reacted strongly to beet western yellows virus (BWYV) antiserum, moderately to bean leafroll virus antiserum, while no reaction was recorded with the antiserum against subterranean clover red leaf virus. In PCR, a fragment of ca. 950 bp was amplified, comprising the 3' end of the open reading frame (ORF) 3, the complete coat protein gene (ORF 4), and the non-translated region in between these ORFs. The nucleotide sequence of the amplified fragment showed high similarity with BWYV (approximately 96%), and lower (50–60%) with other luteoviruses reported to infect legumes. On the basis of these data, the Moroccan isolate was identified as BWYV. This is the first molecular evidence for the occurrence of BWYV on chickpea in Morocco, and on food legumes in general in North Africa.

Production and evaluation of monoclonal antibodies for the detection of beet mild yellowing luteovirus and related strains

A sugar-beet-infecting isolate of beet mild yellowing luteovirus (BMYV), and aBrassica-infecting isolate of beet western yellows luteovirus (BWYV) were used to produce monoclonal antibodies for epidemiological studies with BMYV and related field strains. Thirty-four monoclonal antibodies were tested for their reaction with 9 luteoviruses in triple-antibody-sandwich enzyme-linked immunosorbent assay. One (MAFF 24) is now routinely used in the UK for detecting BMYV and BWYV in plants and aphids, although it does not discriminate between them. Heterologous reactions were detected between some of the monoclonal antibodies and potato leafroll virus (PLRV), bean leafroll virus (BLRV) and barley yellow dwarf virus (BYDV-RPV). 38% of antibodies raised to BWYV reacted with PLRV compared with 4% of those raised to BMYV. Monoclonal antibodies were produced which distinguished a sugar-beet-infecting isolate of BMYV with differing host range and serological properties from the commonly-occurring field strain.

Soybean Dwarf, Bean Leaf Roll, and Beet Western Yellows Luteoviruses in Southeastern U.S. White Clover.

Leaf samples collected from white clover plants in several eastern and southeastern states between 1986 and 1991 were tested for the presence of soybean dwarf virus (SbDV), bean leaf roll virus (BLRV), and beet western yellows virus (BWYV) by aphid transmission and serologyThe majority of the 991 samples were from randomly selected, asymptomatic, white clover plants in or near established clover stands. We report here the widespread occurrence of SbDV and BLRV in the southeastern United States. Nearly 25% of all white clover samples contained SbDV, BLRV, or both, while less than 10% contained BWYV

Nucleotide sequence and E. coli expression of the coat protein gene of the yellowing strain of soybean dwarf luteovirus.

The nucleotide sequence of the coat protein gene of the yellowing (Y) strain of soybean dwarf virus (SbDV) was determined from cloned cDNA. The gene contains 600 nucleotides and encodes a protein of 200 amino acids with a calculated M(r) of 22,200. The identity of the open reading frame (ORF) encoding the coat protein was confirmed by expression of an Escherichia coli beta-galactosidase fusion protein and detection by a dot blot immunoassay. Sequence comparisons of the deduced coat protein amino acids to several luteoviruses demonstrated that the SbDV-Y coat protein ORF shares greatest similarity with bean leaf roll virus (BLRV) (65%).

Survey of faba bean (Vicia faba L.) for viruses in Morocco

A total of 52 faba-bean (Vicia faba L.) fields, located in the main growing areas in Morocco were surveyed for viruses. From 240 samples with symptoms suggestive of virus infection, the following viruses were detected using electron microscopy, serology, and biological indexing: Alfalfa mosaic virus (AMV), bean yellow mosaic virus (BYMV), broad bean mottle virus (BBMV), broad bean stain virus (BBSV), broad bean true mosaic virus (BBTMV), pea earlybrowning virus (PEBV), pea enation mosaic virus (PEMV), pea seed-borne mosaic virus (PSbMV), and a complex of luteoviruses including bean leafroll virus (BLRV). This is the first report of the occurrence of BBTMV, PEMV, PSbMV, and the luteoviruses (including BLRV) of faba bean in Morcco.