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Field survey study was conducted season (2017). Soybeans and weeds were weekly sampled randomly. Thrips adults were identified and counted. Detection of the virus isolate and the natural incidence was determined using; Mechanical transmission, host range, DAS-ELISA, RT-PCR. The natural incidence thrips individuals was detected depending on the SVNV% in thrips individuals and weeds hosts. Ten thrips species were associated with soybean plants in the field. The most abundant species was T. tabaci, average 256.5 average no.of individuals, followed by F. occidentalis (142.5 average no. of individuals), then N. variabilis (86.6/ average no. of individuals). Fourteen thrips species occurred on 5 legumes field crops and 41 weed plant species within soybean field. The highest average number 40.6.of individuals were recorded on Ammi majus. While the lowest one 3.3 average no. of individuals were on Urtica urens. Only 21diagnostic plant species were susceptible to infection with SVNV. G. max and Vigna radiate, were the highest percentage of infection 80% followed by V. unguilata & N. benthamiana, 75%. Egyptian isolate of Soybean vein necrosis virus (SVNV) in this study showed a high degree of similarity and it is closely related to TSWV from Egypt (DQ479968) and TCSV from USA (KY820965) with nucleotide sequence identity of 78%. Four thrips species transmitted SVNV (F. fusca 4.0%, F. schultzei 4.3%, F. tritici 3.3% and N. variabilis 68.0% transmission). Both C. phaseoli and M. sjostedti can acquire the virus but unable to transmit it. The following species; T. tabaci, F. occidentalis, S. dorsallis and T. palmi cannot acquire or transmit SVNV. The incidence of SVNV in the field started by the end of July then increased gradualy from 12.7 to 71.3% by the end of the season. In conclusion, few thrips individuals invaded soybean crops are enough to transmit high rate of SVNV within the crop. Furthermore, several vector species are also abundant on weeds, which are the major sources of soybean viruses transmitted to the crops. This information might be important for control and reduce the incidence of SVNV infection.

Few diseases have emerged in such a short period of time as soybean vein necrosis. The disease is present in all major producing areas in North America, affecting one of the major row field instead of row crops for the United States. Because of the significance of soybean in the agricultural economy and the widespread presence of the disease, the causal agent, soybean vein necrosis virus has been studied by several research groups. Research in the past 10 years has focused on virus epidemiology, management, and effects on yield and seed quality. This communication provides a review of the current knowledge on the virus and the disease.

Soybean thrips (Neohydatothrips variabilis) are one of the most efficient vectors of soybean vein necrosis virus, which can cause severe necrotic symptoms in sensitive soybean plants. To determine which other viruses are associated with soybean thrips, the metatranscriptome of soybean thrips, collected by the Midwest Suction Trap Network during 2018, was analyzed. Contigs assembled from the data revealed a remarkable diversity of virus-like sequences. Of the 181 virus-like sequences identified, 155 were novel and associated primarily with taxa of arthropod-infecting viruses, but sequences similar to plant and fungus-infecting viruses were also identified. The novel viruses were predicted to have positive-sense RNA, negative-stranded RNA, double-stranded RNA, and single-stranded DNA genomes. The assembled sequences included 100 contigs that represented at least 95% coverage of a virus genome or genome segment. Sequences represented 12 previously described arthropod viruses including eight viruses reported from Hubei Province in China, and 12 plant virus sequences of which six have been previously described. The presence of diverse populations of plant viruses within soybean thrips suggests they feed on and acquire viruses from multiple host plant species that could be transmitted to soybean. Assessment of the virome of soybean thrips provides, for the first time, information on the diversity of viruses present in thrips.

Thrips-infesting soybeans were considered of minor economic importance, but recent evidence of their ability to transmit a newly identified soybean virus, Soybean vein necrosis virus (SVNV), has raised their profile as pests. Season-long surveys were conducted using suction traps to determine the effects of temperature and precipitation on the spatiotemporal patterns of three vector species of SVNV, Neohydatothrips variabilis (Beach) (Thysanoptera: Thripidae) (soybean thrips), Frankliniella tritici (Fitch) (Thysanoptera: Thripidae) (eastern flower thrips), and Frankliniella fusca (Hinds) (Thysanoptera: Thripidae) (tobacco thrips) in soybean fields in Indiana in 2013 and 2014. In addition, soybean fields were surveyed for presence of SVNV in both years. We found that the magnitude and timing of thrips activity varied greatly for the three species. N. variabilis activity peaked in mid-August each year. The peak activity for F. tritici occurred between late-June, and a second peak in activity was observed in early-August, while F. fusca activity remained more or less the same with no peak. There was no gradient in thrips populations from southern to northern locations. This suggests that these insects are not migratory and may overwinter in soil or perennial noncrop host plants and other weed hosts in Indiana. The capture rates of N. variabilis and F. tritici were only related to temperature, and capture rates of F. fusca were not related to either variable. SVNV was first detected in mid-late August, which coincided with the peak of the primary vector, N. variabilis. The virus was not detected earlier in the season despite peaks in F. tritici activity. Our results may be used in weather-based models to predict both thrips dynamics as well as SVNV outbreaks.

Soybean vein necrosis virus (SVNV) was first reported in the United States during 2008 and has since rapidly spread to all major soybean-producing regions of North America. In 2013, a 4-year study was initiated to determine the distribution and incidence of the virus in Alabama soybean fields and potential weed hosts in the state. The weed host survey focused on populations of morning glory growing adjacent to maturing soybeans fields, along with additional commonly occurring weed species found in Alabama. SVNV was detected throughout Alabama (27 of 28 counties tested) and was most common in the northern region of the state. The average incidence of SVNV in fields in northern Alabama increased from 31.8% in 2013 to 82.6% in 2016. Average incidence of the virus in central Alabama soybean fields ranged from 5.1 to 14.8%, and southern Alabama fields ranged from 0 to 8.8% over the 3-year period. Only one population of morning glory tested positive for SVNV during the 3-year survey of this potential weed host. None of the 15 additional weed species screened tested positive for SVNV. This study has demonstrated that SVNV is found in Alabama soybean fields throughout the state and that soybeans grown in northern Alabama are at greater risk for infection.

Soybean vein necrosis virus (SVNV), a tospovirus and one of the most widespread soybean viruses in North America, is primarily transmitted by soybean thrips (Neohydatothrips variabilis). Although soybean is not considered the primary plant host for SVNV, there is a dearth of knowledge about alternative host plants for SVNV. We therefore investigated whether commonly present specialty and cover crops in Iowa can serve as alternative hosts for SVNV. Seventeen cover crops and seven specialty crops were tested using mechanical and thrips inoculations. Clear symptoms of SVNV and systemic infection in buckwheat and clear local infection with possible systemic infection on melon were shown. Additionally, we compared soybean thrips feeding on 18 cover crops and determined that they preferred alfalfa, buckwheat, crimson clover, and red clover. Our results suggested that alternative host crops may harbor SVNV and be a possible source of inoculum for soybean.

Orthotospoviruses are acquired by thrips during feeding on infected tissue. Virions travel through the foregut and enter midgut epithelial cells through the interaction between the viral glycoproteins and cellular receptors. Glycoprotein RGD motifs and N-linked glycosylation sites have been predicted to mediate receptor binding or play important roles in virus entry into host cells, yet their function needs to be validated. In this study, peptides derived from the soybean vein necrosis virus N glycoprotein were utilized to identify critical regions in virus-vector interactions. Transmission mediated by single Neohydatothrips variabilis dropped by more than 2/3 when thrips were fed on peptide NASIAAAHEVSQE or the combination of NASIRGDHEVSQE and RLTGECNITKVSLTN when compared to the controls; indicating that this strategy could significantly reduce transmission efficiency, opening new avenues in the control of diseases caused by orthotospoviruses.

Soybean vein necrosis virus (SVNV), the causal agent of the homonymous disease, is a ubiquitous virus in North America. The widespread presence of the virus has led to the hypothesis that mixed infections with other viruses could alter disease symptoms, localization in the plant and even epidemiology. The potential interaction between bean pod mottle virus (BPMV), soybean mosaic virus (SMV), the most economically important soybean viruses in the U.S., and SVNV was assessed in the work presented here. Results revealed that soybean, a local lesion host for SVNV, becomes permissive in the presence of BPMV; whereas there where no obvious interactions observed in mixed infections with SMV.

Soybean vein necrosis virus (SVNV) was first identified in Arkansas and Tennessee in 2008 and is now known to be widespread in the United States and Canada. Multiple species of thrips transmit this and other tospoviruses with Neohydatothrips variabilis (Beach) (soybean thrips) cited as the most efficient vector for SVNV. In this study, 18 soybean, Glycine max (L.) Merr., genotypes were evaluated in four experiments by infesting plants with noninfected and SVNV-infected thrips using choice and no-choice assays. In both choice experiments with noninfected and SVNV-infected thrips, the lowest number of immature soybean thrips occurred on plant introductions (PIs) 229358 and 604464 while cultivars Williams 82 and Williamsfield Illini 3590N supported higher counts of mature thrips. The counts between the two assays (noninfected and SVNV-infected thrips) were positively correlated. In both no-choice experiments with noninfected and SVNV-infected thrips, counts of thrips did not differ by soybean genotypes. Further studies are needed to characterize the inheritance and mechanisms involved in the resistance found in the choice assay.

Soybean vein necrosis virus (SVNV) is a newly discovered species of tospovirus infecting soybean plants that is transmitted by the primary vector, soybean thrips (Neohydatothrips variabilis), and two additional secondary vectors, tobacco thrips (Frankliniella fusca) and eastern flower thrips (F. tritici). This study was undertaken to elucidate the association between virus acquisition [6, 12, 24, and 48 h acquisition access period (AAP)] and transmission efficiency [12, 24, and 48 h inoculation access period (IAP)] in the primary vector, N. variabilis, and to examine the mechanisms of vector competence by analyzing the effect of AAP (6, 12, and 24 h) on virus infection in various tissues. In addition, we examined virus infection in tissues of the two secondary vectors. We found a significant effect of virus acquisition on transmission efficiency, transmission rate post 6 and 48 h AAP was significantly lower than 12 and 24 h AAP. Our analysis did not reveal a correlation between virus transmission rate and virus RNA in corresponding N. variabilis adults. On the contrary, N. variabilis adults harboring higher accumulation of the virus (>104) resulted in lower transmission rates. Analysis of SVNV infection in the tissues revealed the presence of the virus in the foregut, midgut (region 1, 2, and 3), tubular salivary glands and principal salivary glands (PSG) of adults of all three vector species, however, the frequency of infected tissues was highest in N. variabilis followed by F. fusca and F. tritici. The frequency of SVNV infection in individual tissues specifically the salivary glands was lowest after 6 h AAP compared to 12 and 24 h AAP. This finding is in agreement with the transmission assays, where significantly lower virus transmission rate was observed post 6 h AAP. In addition, N. variabilis adults with high PSG infection (12 and 24 h AAP) were likely to have high percentage of foregut and midgut region 2 infection. Overall, results from the transmission assays and immunolabeling experiments suggest that shorter AAP results in reduced virus infection in the various tissues especially PSG, which are important determinants of vector competence in SVNV-thrips interaction.

Soybean vein necrosis virus (SVNV) causes a new emerging disease of soybean that has been recorded in more than 10 states (1,2,3,4) of the United States, but so far no information is available about its presence in soybean crops of Oklahoma. Surveys of commercial soybean fields were conducted for soybean viruses during summer of 2012. A total of 327 samples were randomly collected from soybean fields in 11 counties. Symptoms typical of SVNV infections including leaf chlorosis and leaf-vein necrosis were observed on some soybean plants in the field (4). All soybean leaf samples were tested against SVNV polyclonal antisera obtained from AC Diagnostics, Inc. (Fayetteville, AR) by dot-immunobinding assay (DIBA) (1). Fifty-three samples reacted positively with SVNV antisera. Total RNA was extracted from three DIBA-positive samples collected from soybean plants in Choctaw County and tested by reverse transcription (RT)-PCR using SVNV-specific primers (forward primer 5′-ATGTTCTCTCTATAATAGCCA and reverse primer 5′-ACCCATAACAATTGATCAAGA-3′) that were designed from the available sequence in the GenBank (Accession No. GU722317.1) to amplify a fragment from RNA1. A band of the expected size of 344 bp was observed on a 1% agarose gel in all three samples. The PCR products were purified using QIAquick PCR Purification Kit (QIAGEN, Valencia, CA), cloned (pGEM-T Easy Vector, Promega, Madison, WI) and sequenced in both directions. The consensus sequence of the 344-bp fragment was 99% identical with the corresponding region of RNA 1 of SVNV isolate ‘Milan_TN’ (Accession No. GU722317.1). These results confirmed the presence of SVNV in soybean fields, which are mostly located in Criage, Choctaw, Hughes, LeFlore, Mayes, Muskogee, McCurtain, Okmulgee, Ottawa, Rogers, and Sequoyah counties of Oklahoma. None of the samples collected from north central or western parts of the state were positive against SVNV. To our knowledge, this is the first report of SVNV in soybean crops in Oklahoma. Soybean is one of the major oil seed crops cultivated on approximately 200,000 hectares annually in Oklahoma and the presence of SVNV could pose a potential threat to the production of soybean in the future. References: (1) J. L. Jacobs and M. I. Chilvers. Plant Dis. 97:1387, 2013. (2) J. Han et al. Plant Dis. 97:693, 2013. (3) D. L. Smith et al. Plant Dis. 97:693, 2013. (4) J. Zhou et al. Virus Genes 43:289, 2011.

The prevalence of soybean vein necrosis virus (SVNV) in soybean (Glycine max (L.), Merr.) across major producing areas in North America and its negative impact on seed oil content demonstrate the need for effective control strategies against the virus. Varieties with resistance to vectors could modify their behavior, reduce transmission and consequently disease incidence. In this study we evaluated feeding preference of viruliferous Neohydatothrips variabilis (Beach), the primary vector of SVNV on selected genotypes with different leaf pubescence. Low feeding genotypes were studied in-depth using imaging software to assess thrips injury in high resolution. We found that damage was reduced among genotypes with low pubescence levels. Given that there is no known SVNV-resistant germplasm, identifying resistance to vectors is a promising alternative strategy. The genotypes identified in this study could be the basis for breeding N. variabilis-resistant cultivars.

Soybean vein necrosis virus (SVNV), a new virus in the genus Orthotospovirus, has been found in all soybean-growing regions in the United States and Ontario, Canada. Soybean thrips, Neohydatothrips variabilis (Beach) (Thysanoptera: Thripidae), tobacco thrips, Frankliniella fusca (Hinds) (Thysanoptera: Thripidae), and eastern flower thrips, Frankliniella tritici (Fitch) (Thysanoptera: Thripidae) are reported vectors of this virus, but there are no reports on their distribution in Alabama. A monitoring study was conducted in 2015 and 2016 to determine thrips species composition and abundance in Alabama soybean agroecosystems. Thrips were monitored weekly by collecting them on yellow sticky traps and soybean plant parts including foliage and reproductive structures. All three reported vectors of SVNV were identified in Alabama, with N. variabilis and F. tritici as the predominant species, while F. fusca was not consistently collected from soybean plants. Four additional thrips species were collected, of which Echinothrips americanus (Morgan) (Thysanoptera: Thripidae) was commonly found on soybean at all three locations. Results presented in this study provide new information about seasonal thrips species abundance in soybean agroecosystems in Alabama, and is an important first step to understanding thrips vector species of epidemiological importance in the Southern United States.

A new distribution map is provided for Soybean vein necrosis virus. Tymovirales: Bunyaviridae: Tospovirus. Hosts: soyabean ( Glycine max ). Information is given on the geographical distribution in North America (Canada, Ontario, USA, Alabama, Arkansas, Delaware, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Michigan, Mississippi, Missouri, New York, Ohio, Oklahoma, Pennsylvania, Tennessee, Virginia and Wisconsin).

Soybean vein necrosis virus (SVNV) is a virus originally discovered in Arkansas and Tennessee and is currently present in all major soybean-producing states in the United States and Canada (Zhou and Tzanetakis 2013). Studies were carried out to investigate the role of kudzu (Pueraria montana) in SVNV epidemiology. Kudzu is present in millions of acres in the southeastern United States and is known to host at least another soybean-infecting virus, tobacco ringspot virus (TRSV) (Aboughanem-Sabanadzovic et al. 2014; Khankum et al. 2013). Eighty-five samples collected from 15 Mississippi counties during September 2015 were tested for SVNV infections using DAS-ELISA (Agdia Inc, U.S.A.) and three were infected by the virus. Two of the samples displayed mild deformation of young leaves, whereas the third was symptomless. In order to verify the results, virus-specific RT-PCR tests were performed on nucleic acid extracts from all ELISA-positive samples along with three SVNV-free kudzu plants and controls, represented by SVNV-infected and healthy soybeans. A DNA band of 236 bp corresponding to the NSs gene (Zhou and Tzanetakis 2013) was amplified only from the three ELISA-positive kudzu samples and positive controls. The products were directly sequenced in both directions and confirmed to be SVNV-specific as they shared 96 to 99% nt identity with corresponding region of the SVNV reference isolate (GenBank accession no. GU722319). In a greenhouse-based study, first instar larvae of soybean thrips (Neohydatothrips variabilis Beach) were fed on symptomatic soybean for virus acquisition and transferred to eight SVNV-free kudzu seedlings as described (Zhou and Tzanetakis 2013). Leaf and root tissues were randomly collected from virus-inoculated and mock-inoculated kudzu, respectively, at 6 weeks post inoculation. Total nucleic acids were isolated and RT-PCR was performed using primer set SdetF/SdetR (Zhou et al. 2011). Amplification products corresponding to the complete NP gene (834 bp) were obtained in both leaf and root tissues from five inoculated plants and shared 97 to 99% identity with the reference isolate (GenBank accession no. GU722319), whereas there was no amplification from mock-inoculated controls. Those results were further confirmed by dot blot immunoassay with infected plants remaining asymptomatic for at least a month post inoculation. Our findings represent the first report of SVNV infections of kudzu in the U.S.A. and the world. Kudzu is likely to play a role in the epidemiology of virus and disease. Furthermore, our results expand the range of pathogens (Asian soybean rust, TRSV) and insects (kudzu bug) that kudzu can sustain, indicating its ecological impact as an invasive species.

Soybean (Glycine max) is one of the most important crops as a source of high-quality protein and oil. In India, soybean area has expanded with the introduction of high-yielding varieties with wide adaptability, which also favored the development of new diseases with increased incidence. During 2016, 38 samples from initial varietal trials of soybean cultivars from India exhibiting symptoms such as mosaic, mottling, necrosis, and puckering were collected from the fields of the Indian Agricultural Research Institute, New Delhi, India, and tested for the presence of viruses, namely, Cowpea mild mottle virus, Groundnut bud necrosis virus, Soybean mosaic virus, Soybean vein necrosis virus, Soybean yellow mottle mosaic virus (SYMMV), and Tobacco streak virus. Crude sap from 3 of the 38 samples strongly reacted with the polyclonal antibodies raised against SYMMV in direct antibody coating ELISA (A₄₀₅ₙₘ= 1.2 to 1.8) (Sandra et al. 2015). To confirm the SYMMV infection, total RNA was extracted from the ELISA-positive soybean leaf samples showing mosaic and mottling symptoms using the SV Total RNA isolation system (Promega, Madison, WI) followed by reverse-transcription polymerase chain reaction (RT-PCR) with coat protein (CP) gene specific primers (forward, 5′-ATGAATTCATGAATGGAACAATGCTCACCGT-3′; reverse, 5′-CAAAGCTTAGTGTGTGGGTTTTAACTGGCGTTGTTA-3′) (Sandra et al. 2015). The RT-PCR product of 1,065 base pairs was cloned into TA cloning vector (Real Biotech Corporation), and the clones were sequenced in both orientations and deposited in GenBank (accession no. MG768974). Sequence analysis of the CP gene showed 98 to 100% identity with Indian isolates (KR260903, KR260902, and KP259608) followed by 82 and 92% similarity with Korean isolates of SYMMV at nucleotide and amino acid levels, respectively. Identity at the nucleotide and amino acid level of 29 to 42% and 16 to 25% was observed with the corresponding CP region of other carmoviruses. For further confirmation, French bean seedlings (cv. Pusa Parvati) were mechanically sap inoculated with an extract from an ELISA-positive soybean leaf sample, and these seedlings showed systemic chlorotic blotches after 10 to 12 days postinoculation, which were then confirmed by ELISA and RT-PCR as above. Previously, SYMMV was reported on soybean from South Korea and North America (Li et al. 2009; Nam et al. 2009). More recently, SYMMV was reported on mungbean and urdbean from India (Sandra et al. 2015). To our knowledge, this is the first report of natural infection of soybean by SYMMV in India and suggests that this newly identified SYMMV may be adapting to other leguminous host plant species.

Soybean vein necrosis virus (SVNV; genus Tospovirus; Family Bunyaviridae) is a negative-sense single-stranded RNA virus that has been detected across the United States and in Ontario, Canada. In 2013, a seed lot of a commercial soybean variety (Glycine max) with a high percentage of discolored, deformed and undersized seed was obtained. A random sample of this seed was planted in a growth room under standard conditions. Germination was greater than 90% and the resulting seedlings looked normal. Four composite samples of six plants each were tested by reverse transcription polymerase chain reaction (RT-PCR) using published primers complimentary to the S genomic segment of SVNV. Two composite leaflet samples retrieved from seedlings yielded amplicons with a size and sequence predictive of SVNV. Additional testing of twelve arbitrarily selected individual plants resulted in the identification of two SVNV positive plants. Experiments were repeated by growing seedlings from the same seed lot in an isolated room inside a thrips-proof cage to further eliminate any external source of infection. Also, increased care was taken to reduce any possible PCR contamination. Three positive plants out of forty-eight were found using these measures. Published and newly designed primers for the L and M RNAs of SVNV were also used to test the extracted RNA and strengthen the diagnosis of viral infection. In experiments, by three scientists, in two different labs all three genomic RNAs of SVNV were amplified in these plant materials. RNA-seq analysis was also conducted using RNA extracted from a composite seedling sample found to be SVNV-positive and a symptomatic sample collected from the field. This analysis revealed both sense and anti-sense reads from all three gene segments in both samples. We have shown that SVNV can be transmitted in seed to seedlings from an infected seed lot at a rate of 6%. To our knowledge this is the first report of seed-transmission of a Tospovirus.

Soybean, one of the world's most important sources of animal feed and vegetable oil, can be infected by numerous viruses. However, only a small number of the viruses that can potentially infect soybean are considered as major economic problems to soybean production. Therefore, we consider management options available to control diseases caused by eight viruses that cause, or have the potential to cause, significant economic loss to producers. We summarize management tactics in use and suggest direction for the future. Clearly, the most important tactic is disease resistance. Several resistance genes are available for three of the eight viruses discussed. Other options include use of virus-free seed and avoidance of alternative virus hosts when planting. Attempts at arthropod vector control have generally not provided consistent disease management. In the future, disease management will be considerably enhanced by knowledge of the interaction between soybean and viral proteins. Identification of genes required for soybean defense may represent key regulatory hubs that will enhance or broaden the spectrum of basal resistance to viruses. It may be possible to create new recessive or dominant negative alleles of host proteins that do not support viral functions but perform normal cellular function. The future approach to virus control based on gene editing or exploiting allelic diversity points to necessary research into soybean-virus interactions. This will help to generate the knowledge needed for rational design of durable resistance that will maximize global production.

With the discovery of Neohydatothrips variabilis (Beach) as a vector of Soybean vein necrosis virus (Family Bunyaviridae Genus Tospovirus), a relatively new pathogen of soybean, a multiyear study was initiated in Wisconsin (2013 and 2014) and Iowa (2014 and 2015) to determine the phenology and species composition of thrips in soybean fields. Yellow sticky card traps were used to sample thrips at regular intervals in five counties within each state's primary soybean-growing region. The assemblage of species present in Wisconsin was determined in all site-years, revealing that N. variabilis and other known vectors of tospoviruses were a relatively small percentage of the total thrips captures in 2013 (1.6%) and 2014 (3.6%). A repeated measures analysis was conducted on cumulative proportion thrips capture data within each state's sampling year to investigate differences in phenology, and standardized cumulative insect days were analyzed between sampling years within each state to determine differences in the relative magnitude of populations. Distinct seasonal trends were not detected based on location, as originally hypothesized, and thrips populations varied significantly among locations and between years. These results suggest that thrips populations may be overwintering in northern climates instead of relying solely on migrations to colonize northern soybean fields.

A new, widespread disease was recently observed in soybean in the United States. The disease, named Soybean vein necrosis, is manifested by intraveinal chlorosis and necrosis, and has been found in almost all of the 50 fields visited over a period of 3 years in the midwest and midsouth part of the United States. A virus was isolated from symptomatic material, and detection protocols were developed. More than 150 symptomatic specimens collected from seven US States were tested, and all were found positive for the virus unlike 75 asymptomatic samples, revealing the absolute association between virus and disease. Protein pairwise comparisons coupled with phylogenetic analyses indicate that the virus is a new member of the genus Tospovirus.

Soybean vein necrosis virus (SVNV) is associated with an emerging disease in soybean producing regions of the United States. Soybean leaves with necrotic vein symptoms were initially noted in 2008 or 2009 in fields across Arkansas, Kansas, Missouri, Illinois, Mississippi, Tennessee, and Kentucky and SVNV was determined to be the causal agent (2). In 2012, widespread reports of SVNV were made across most soybean (Glycine max) producing states including the recent confirmation of SVNV in Iowa and Wisconsin (1). Foliar symptoms similar to those reported for SVNV were observed at approximately 1 to 10% incidence in soybean fields across Michigan in late August and September of 2012, including fields located in Cass, Ingham, Midland, Saginaw, and Van Buren counties. Symptoms included chlorosis and necrosis which initiated on the veins with subsequent spread across the leaf. An initial sample collected from the East Lansing Agricultural Research Station was confirmed to have SVNV with a polyclonal antibody using double antibody sandwich (DAS)-ELISA at AC Diagnostics, Inc. (Fayetteville, AR) and with reverse transcription PCR by Ioannis Tzanetakis, University of Arkansas, Fayetteville. Additional samples from five fields were subsequently collected from Cass, Ingham, and Van Buren counties. Duplicate leaf tissue samples were tested with DAS-ELISA using the SVNV test kit (AC Diagnostics). All symptomatic leaf samples exhibited a strong positive reaction based on the optical density reading at 405 nm. Absorbance reading that exceeded the healthy soybean tissue by a standard deviation of +3× were considered positive. Total RNA was also extracted from each sample using the RNeasy Plant Mini Kit (Qiagen, Germantown, MD). Complementary DNA (cDNA) was generated using virus-specific LdetR and SdetR primers (2) with the High Capacity RT cDNA kit (Life Technologies; Carlsbad, CA). The cDNA was used as template for PCR with the SVNV-specific primers that amplify regions of the L (LdetF/LdetR) and the S (SdetF/SdetR) RNAs (1). Amplification products of the expected 297 and 861 bp size, respectively, were detected in all symptomatic samples while no amplification products were generated from healthy soybean plant tissues grown under greenhouse conditions. Significantly, this is the first documentation and confirmation of the widespread prevalence of SVNV across the state of Michigan in 2012. References: (1) D. L. Smith et al. Plant Dis. http://dx.doi.org/10.1094/PDIS-11-12-1096-PDN . (2) J. Zhou et al. Virus Genes 43:289, 2011.