Soybean Yellow Mottle Mosaic Virus Research Articles

Complete genome sequence of seed-transmitted soybean yellow mottle mosaic virus from soybeans in Korea

ABSTRACT Soybean yellow mottle mosaic virus (SYMMV), a member of the genus Gammacarmovirus , remains poorly understood in terms of its transmission pathway. This study reveals the complete genome sequence of a seed-transmitted isolate, ST-HB56, contributing to the understanding of SYMMV’s ecological dynamics.

Correlation of Weather Variables on Emergence of a Virus Disease Bud Necrosis Disease of Greengram Incited by Soybean Yellow Mottle Mosaic Virus at Raichur, Karnataka

Greengram [(Vigna radiata (L.) Wilczek] is the important pulse crop after chickpea and pigeonpea cultivated in India which is called as “Queen of pulses”, the crop is proned to be infected by many fungal and bacterial diseases. In recent years emergence of a virus disease bud necrosis of greengram was noticed in Raichur and the incidence of disease gradually increased in greengram growing areas of Karnataka. Incidence of bud necrosis disease of greengram and correlation with weather factors was studied during Kharif 2021 at research plot and MARS, UAS, Raichur, Karnataka. The study reveals that, on all four dates of sowing (25th June, 1st July, 9th July and 23rd July 2021), disease was initiated at 25 DAS and highest disease incidence was observed at 75 DAS. The peak activity of thrips was noticed during August month. The weather variables viz., maximum temperature was more than 32 °C, minimum temperature was more than 22°C, rainfall was less than 19 mm/day, morning relative humidity was less than 91 per cent, evening relative humidity more than 44 per cent, evaporation 4.3 mm/day and sunshine hours less than 6 hr/day was favorable for bud necrosis disease in four dates of sowing. Whereas, morning relative humidity, evening relative humidity and age of the crops were having positive relationship with progress of bud necrosis on all four dates of sowing. Thrips and rainfall showed a positive correlation with disease incidence in all dates of sowing except the fourth date of sowing.

Molecular and biological characterization of soybean yellow mottle mosaic virus severe strain infecting soybean in India.

The online version contains supplementary material available at 10.1007/s13205-021-02925-2.

First Report of Soybean Yellow Mottle Mosaic Virus Infecting Soybean in China

First Report of Soybean Yellow Mottle Mosaic Virus Infecting Soybean in China

Effect of temperature on systemic infection and symptom expression induced by Soybean yellow mottle mosaic virus in leguminous hosts

Temperature is one of the key factors influencing the viral disease development in plants. In this study effect of temperature on SYMMV accumulation and systemic movement was studied in French bean, mungbean and soybean cultivars by keeping them at temperatures range 22-25 °C, 26-29 °C and 30-33 °C. The proliferation of the virus under these conditions was confirmed through symptomatology, DAC-ELISA, RT-PCR with coat protein specific primers and RT-qPCR. French bean plants displayed symptoms by 12dpi at low temperature (22-25 °C) and by 3dpi at medium temperatures (26-29 °C) with continuous increase in viral accumulation from 0 to 24dpi. At high temperatures (30-33 °C), French bean did not show symptoms up to 12dpi but the virus accumulated and moved systemically. However, there was a decline in viral copy number after 12dpi. Mungbean plants showed mottling, mosaic and puckering symptoms at 22-25 °C and 26-29 °C and necrotic symptoms at 30-33 °C. Irrespective of temperature there was an increase in viral accumulation in mungbean from 0 days to 24dpi. Soybean plants showed veinal mild mottling at low and medium temperatures where as no peculiar symptom expression observed at high temperatures. Soybean also showed the reduction of viral copy number from 12 days to 24dpi at low and medium temperatures and from 6 days to 24dpi at high temperatures. These results indicate that temperature played an important role in SYMMV accumulation, movement and symptom expression in these three leguminous plant species. This study also demonstrates that SYMMV can replicate and spread in mungbean plants irrespective of the temperature.

Seed transmission of a distinct soybean yellow mottle mosaic virus strain identified from India in natural and experimental hosts

Soybean yellow mottle mosaic virus (SYMMV) is a newly identified member of the genus Gammacarmovirus from grain legumes in India. As the modes of transmission of this virus have not been described, we assessed the possibility of SYMMV to be transmitted through seed collected from field infected mungbean plants and mechanically sap inoculated French bean plants using serological and molecular techniques followed by progeny assays. Direct antigen coated enzyme linked immunosorbent assay (DAC-ELISA) and reverse transcription polymerase chain reaction (RT-PCR) results are inconsistent with field infected mungbean seed tissues to ensure seed transmissibility irrespective of seed number used. Seed from mechanical sap inoculated French bean showed higher absorbance values in DAC-ELISA and amplification corresponding to replicase, movement and coat protein regions of SYMMV genome. The relative accumulation of SYMMV was higher in pod walls, immature seed and stamens and stigma of mechanical sap inoculated French bean. Progeny assays with infected seed revealed the seed transmissibility of SYMMV at the rate of 63.33% in mungbeanand 73.33% in French bean. Mechanical sap inoculation of mungbean progeny seedlings on French bean cv. Pusa Parvati produced characteristic symptoms of SYMMV. The results obtained from this study demonstrate that SYMMV is seed borne in nature and can be transmitted to next generation seedlings. This is the first report of seed transmission of SYMMV in mungbean and French bean.

Development of Soybean Yellow Mottle Mosaic Virus-Based Expression Vector for Heterologous Protein Expression in French Bean.

Plant virus-based vectors provide attractive and valuable tools for rapid production of recombinant protein in large quantities as they produce systemic infections in differentiated plant tissues. In the present study, we engineered the Soybean yellow mottle mosaic virus (SYMMV) as a gene expression vector which is a promising candidate for systemic expression of foreign proteins in French bean plants. Full virus vector strategy was exploited for insertion of foreign gene by inserting MCS through PCR in the circular pJET-SYMMV clone. To examine the ability of the SYMMV vector system, GFP gene was cloned after the start codon of coat protein (CP) so that its expression was driven by the SYMMV-CP subgenomic promoter. When in vitro run off SYMMV-GFP transcript was mechanically inoculated to French bean leaves, good level of GFP expression was observed through confocal microscopy up to 40 dpi. Expression of heterologous protein was also confirmed through ISEM, DAC-ELISA and RT-PCR with specific primers at 20dpi. The recombinant SYMMV construct was stable in in vitro runoff transcript inoculated plants but the inserted GFP was lost in progeny virion inoculated plants. The system developed here will be useful for further studies of SYMMV gene functions and exploitation of SYMMV as a gene expression vector.

First Report of Soybean yellow mottle mosaic virus on Soybean (Glycine max) in India

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.

First Report of Soybean mosaic virus and Soybean yellow mottle mosaic virus in Vigna angularis

In 2015 and 2016, 203 samples of adzuki bean (Vigna angularis) exhibiting viral disease-like symptoms, such as mosaic, mottle, yellowing, dwarfing and leaf rolling, were collected from 18 cities/counties in Korea. Total RNA was prepared from a pooled sample using easy-spinTM Total RNA Extraction Kit (iNtRON Biotechnology, Seongnam, Korea) and used for high-throughput paired-end RNA sequencing. Raw data analysis was conducted by Illumina HiSeq 2500 System at the Theragen Etex Bio Institute (Suwon, Korea) and SG-VIPdb at SeqGenesis (Daejeon, Korea), respectively, as previously described (Lim et al. 2015). As expected, 239 and 10 contigs related to Bean common mosaic virus and Cucumber mosaic virus, which have been previously reported in adzuki bean, were obtained from the adzuki bean transcriptome, respectively. However, in addition to this, 143 and 8 contigs were attributed to two soybean viruses, Soybean mosaic virus (SMV) and Soybean yellow mottle mosaic virus (SYMMV), respectively. To confirm the presen...

Genome characterization, infectivity assays of in vitro and in vivo infectious transcripts of soybean yellow mottle mosaic virus from India reveals a novel short mild genotype

Nucleotide sequence of a distinct soybean yellow mottle mosaic virusisolate from Vignaradiata (mungbean isolate, SYMMV-Mb) from India was determined and compared with othermembers of the family Tombusviridae. The complete monopartite single-stranded RNA genome of SYMMV-Mb consisted of 3974nt with six putative open reading frames and includes 5′ and 3′ untranslated regions of 35 and 254nt, respectively. SYMMV-Mb genome shared 75% nt sequence identity at complete genome level and 67–92% identity at all ORFs level with SYMMV Korean and USA isolates (soybean isolates) followed by CPMoV, whereas it shared very low identity with other tombusviridae members (5–41%). A full-length infectious cDNA clone of the SYMMV-Mb placed under the control of the T7 RNA polymerase and the CaMV35S promoters was generated and French bean plants on mechanical inoculation with in vitro RNA transcripts, p35SSYMMV-O4 plasmid and agroinoculation with p35SSYMMV-O4 showed symptoms typical of SYMMV-Mb infection. The infection was confirmed by DAC-ELISA, ISEM, RT-PCR and mechanical transmission to new plant species. Further testing of different plant species with agroinoculation of p35SSYMMV-O4 showed delay in symptoms but indistinguishable from mechanical sap inoculation and the infection was confirmed by DAC-ELISA, RT-PCR and mechanical transmission to new plants. The system developed here will be useful for further studies on pathogenecity, viral gene functions, plant-virus-vector interactions of SYMMV-Mb and to utilize it as a gene expression and silencing vector.

Diagnosis of a new variant of soybean yellow mottle mosaic virus with extended host-range in India.

Soybean yellow mottle mosaic virus (SYMMV, genus Carmovirus) was previously known to occur in South Korea and USA causing bright yellow mosaic in soybean. In this study, SYMMV (Car-Mb14 isolate) was isolated from mungbean (Vigna radiata) exhibiting mild mottling and puckering symptoms in the experimental field at Indian Agricultural Research Institute, New Delhi during 2012. The virus isolate, Car-Mb14 induced veinal mottling, mild mottling, chlorotic blotching, local and systemic necrosis in soybean, mungbean, blackgram, French bean and guar bean, respectively. The symptomatology of the present isolate of SYMMV was different from the previously reported South Korean isolate, as the later did not induce symptoms in any of the above legumes other than soybean. The present isolate was phylogenetically distinct and shared 90-93% sequence identity in coat protein (CP) of 52 SYMMV isolates reported from Korea and USA. In order to know the serological relationships, the CP gene of the present isolate was over expressed as a 39kDa protein in E. coli and an antiserum of 1:16,000titer against the recombinant CP was produced. Serological cross reactivity analysis revealed that SYMMV was serologically related to blackgram mottle virus but not to cowpea mottle virus, the other legume infecting carmoviruses. The antiserum was used to detect prevalence of SYMMV in legume crops by ELISA. Out of 145 field samples of legumes (mungbean, blackgram, French bean and soybean) collected from different places in India, SYMMV was detected only in 16 samples of mungbean and one sample of blackgram. The natural infection of SYMMV in mungbean and blackgram was further confirmed based on CP gene sequence. This study provides evidence of occurrence of a new variant of SYMMV with distinct symptom phenotype and extended host-range in India.

A 2014 Nationwide Survey of the Distribution of Soybean Mosaic Virus (SMV), Soybean Yellow Mottle Mosaic Virus (SYMMV) and Soybean Yellow Common Mosaic Virus (SYCMV) Major Viruses in South Korean Soybean Fields, and Changes from 2012 Isolate Prevalence.

A 2014 Nationwide Survey of the Distribution of Soybean Mosaic Virus (SMV), Soybean Yellow Mottle Mosaic Virus (SYMMV) and Soybean Yellow Common Mosaic Virus (SYCMV) Major Viruses in South Korean Soybean Fields, and Changes from 2012 Isolate Prevalence.

A High Throughput Soybean Gene Identification System Developed using Soybean Yellow Common Mosaic Virus (SYCMV)

Soybean yellow common mosaic virus (SYCMV) was recently reported from Korea, and a subsequent survey of soybean fields found that SYCMV, Soybean yellow mottle mosaic virus (SYMMV), and Soybean mosaic virus (SMV) infections were widespread. SYCMV has recently been developed into a Virus Inducing Gene Silencing (VIGS) vector for use as a reverse genetics tool for soybean, and here we report a modified SYCMV VIGS vector containing a new restriction enzyme site in the 3' non-coding region into which we inserted the Gateway system. Ultrasonically generated c.300 bp random fragments of Glycine max cDNA were inserted into the SYCMV VIGS vector, and individual colonies containing G. max cDNA were inocu- lated to cultivar Williams 82. We monitored the phenotype of inoculated soybean, and selected obvious visi- ble phenotypes caused by SYCMV-induced gene silencing which could enable annotation of gene function of unknown gene fragments inserted into SYCMV. Here, we describe development of a high-throughput SYCMV VIGS vector for gene function identification in soybean.

First Report of Peanut mottle virus Infecting Soybean in South Korea.

In July 2013, soybean (Glycine max) plants at the research field in Daegu, South Korea, showed virus-like symptoms, such as mosaic, mottle, yellowing, and stunting. Overall, there were approximately 1% of soybean plants that showed these symptoms. Sixteen soybean samples were collected based on visual symptoms and subjected to laboratory characterization. Total RNA was extracted from each sample with the Tri Reagent (Molecular Research Center, Cincinnati, OH) and cDNA was synthesized using random N25 primer with RevertAid Reverse Transcriptase (Thermo Scientific, Waltham, MA), according to the manufacturers' instructions. All samples were tested by PCR with Prime Taq Premix (2X) (GeNet Bio, Daejeon, Korea) and primer sets specific to Soybean mosaic virus (SMV; 5'-CATATCAGTTTGTTGGGCA-3' and 5'-TGCCTATACCCTCAACAT-3'), Peanut stunt virus (PSV; 5'-TGACCGCGTGCCAGTAGGAT-3' and 5'-AGGTDGCTTTCTWTTGRATTTA-3'), Soybean yellow mottle mosaic virus (SYMMV; 5'-CAACCCTCAGCCACATTCAACTAT-3' and 5'-TCTAACCACCCCACCCGAAGGATT-3'), and Soybean yellow common mosaic virus (SYCMV; 5'-TTGGCTGAGAGGAGTGGCTT-3' and 5'-TGCGGTCGTGTAGTCAGTG-3'). Among 16 samples tested, five were positive for SMV and two for SYMMV. Three samples were found infected by both SMV and SYMMV and four by both SMV and PSV. Since two of the symptomatic samples were not infected by viruses described above, a pair of primers specific to Peanut mottle virus (PeMoV; 5'-GCTGTGAATTGTTGTTGAGAA-3' and 5'-ACAATGATGAAGTTCGTTAC-3') was tested (1). All 16 samples were subjected to RT-PCR with primers specific to PeMoV. Four were found positive for PeMoV. Two of them were already found infected with SYMMV. In order to identify the complete nucleotide sequences of PeMoV coat protein (CP), another primer set (5'-TGAGCAGGAAAGAATTGTTTC-3' and 5'-GGAAGCGATATACACACCAAC-3') was used. RT-PCR product was cloned into RBC TA Cloning Vector (RBC Bioscience, Taipei, Taiwan) and the nucleotide sequence of the insert was determined by Macrogen (Seoul, Korea). CP gene of the PeMoV (GenBank Accession No. KJ664838) showed the highest nucleotide sequence identity with PeMoV isolate Habin (KF977830; 99% identity), and the highest amino acid identity with GenBank Accession No. ABI97347 (100% identity). In order to fulfill Koch's postulates, several G. max cv. Williams 82 were inoculated with the extracts of PeMoV-infected leaf tissue. At 14 days post-inoculation, plants showed systemic mottle symptoms. These symptomatic plants were subjected to RT-PCR, and the nucleotide sequences of the PCR product were found identical to that of the virus in the inoculum. To our knowledge, this is the first report of soybean-infecting PeMoV, a member of the genus Potyvirus in the family Potyviridae, in South Korea. Reference: (1) R. G. Dietzgen et al. Plant Dis. 85:989, 2001.

Severe Outbreak of the Emerging Soybean Viruses in Korea: An Increasing Threat

To determine the current incidence of Soybean yellow mottle mosaic virus (SYMMV), Soybean yellow common mosaic virus (SYCMV), and Soybean mosaic virus (SMV) in Korea, a nationwide survey was performed in 2013. A total of 417 soybean samples with typical virus symptoms were collected from 9 large-scale soybean-cultivated areas. To identify viruses from the collected samples, RT-PCR was performed using specific primers for SMV, SYMMV, or SYCMV. To confirm the RT-PCR results, PCR products were purified and sequenced. 22 July 2014. 18 August 2014.

영세농가 콩 재배지의 Soybean mosaic virus, Soybean yellow mottle mosaic virus 및 Soybean yellow common mosaic virus 병 발생 조사

Soybean yellow mottle mosaic virus(SYMMV)와 Soybean yellow common mosaic virus(SYCMV) 병 발생은 최근에 우리나라에 보고되었지만 두 바이러스 병의 전국적인 분포에 대한 조사가 이루어지지 않아 본 연구팀은 2012년에 영세 농가를 중심으로 전국적인 조사를 실시하였다. 전국에 걸쳐 채집한 682점의 시료를 SYMMV, SYCMV, 그리고 Soybean mosaic virus(SMV) 특이 프라이머를 이용하여 진단한 결과, SMV 102점, SYMMV 116점, SYCMV는 17점이 PCR 양성으로 나타났다. SYMMV와 SYCMV의 복합감염은 검출되지 않았으나, SMV와 SYMMV 혹은 SMV와 SYCMV 복합감염은 각각 1건과 5건이 확인되었다. 처음으로 실시한 영세농가의 콩 바이러스 병 조사를 근거로 추정할 때, 바이러스의 발생은 자가 채종으로 인한 종자전염으로부터 발생되었을 것으로 추정된다. 따라서 바이러스 병의 예방을 위해서는 감염종자 관리 및 무병종자 보급이 무엇보다 필요함을 알 수 있다. Soybean yellow mottle mosaic virus (SYMMV) and Soybean yellow common mosaic virus (SYCMV) were recently isolated in Korea, and it has not been reported how two viruses were dispersed in Korea. In 2012, we performed nationwide survey in subsistence soybean farming. Suspicious virus-infected infected leave were collected from the field and a total of 682 soybean tissue samples were assayed by RT-PCR using triplex primers detecting SYMMV, SYCMV, and Soybean mosaic virus (SMV). On hundred two samples showed SMV positive, and SYMMV and SYCMV were detected in 116 and 17 tissue samples, respectively. No sample showed double infection of SYMMV and SYCMV, but there were double infection tissues indicating two viruses positive of SMV plus SYMMV (5 tissue samples) and SMV plus SYCMV (1 tissue sample). Through this first subsistence soybean farming field survey, we assumed soybean viruses were originated from home seed production managed by farmer. Thus, in order to prevent possible seed transmission and further damage caused by virus transmission, virus-free commercial soybean seeds are recommended to be planted.

Soybean yellow mottle mosaic virus의 자연기주와 병환

2006년에서 2007년까지 콩연구센터 육종포장 주변에서 잡초 서식상황을 조사한 결과 31과 74속 96종의 식물이 확인되었다. SYMMV의 자연기주 또는 중간기주를 동정하기 위하여 26과 84종의 식물체가 포함되는 495점의 시료를 RT-PC R로 분석한 결과, 단지 콩과 식물에서(돌콩, 새팥, 토끼풀, 비수리)만 SYMMV가 검출되었다. SYMMV를 가지고 있는 콩과 식물 중에서 분석한 돌콩의 3분의 1이상이 SYMMV를 보독하고 있는 것으로 보아 돌콩은 SYMMV의 감염원으로써 중요한 역할을 담당하는 것으로 생각된다. 돌콩은 SYMMV에 7월 중순경에 감염되는 것으로 추정되었다. 돌콩에서 SYMMV의 빠른 감염시기, 높은 종자감염율 그리고 종자전염과 같은 결과로 볼 때, 돌콩은 SYMMV의 생활사 완성에 큰 역할을 담당하고 있는 것으로 판단된다. In surveys of weed occurrence undertaken from 2006 to 2007, near to the Daegu experimental fields of the National Institute of Crop Science, plants belonging to 31 families, 74 genera and 96 species were found. For the investigation of the natural or alternative hosts of Soybean yellow mottle mosaic virus (SYMMV), 495 plant samples belonging to 26 families 84 species were subjected to RT-PCR. SYMMV was detected only from legume plants such as Glycine soja, Vigna angularis var. nipponensis, Trifolium repens, and Lespedeza cuneata. Among legume plants tested, more than a third of G. soja (wild soybean) contained SYMMV, indicating that the wild soybean played an important role as a reservoir of SYMMV. Wild soybeans may be infected with SYMMV as early as mid-July. Considering the results of early infection and the high infection rate of seed and seed transmission of SYMMV in G. soja, wild soybeans may have played an important role in the completion of disease cycle of the virus.

First Report of Soybean yellow mottle mosaic virus in Soybean in North America.

Soybean yellow mottle mosaic virus (SYMMV) is a soybean-infecting virus recently discovered in Korea that initially induces bright yellow mosaic on leaves followed by stunting and reduced growth of older leaves (1). Nucleotide sequence analysis of genomic RNA of the Korean SYMMV isolate suggested that the virus is a new member of the genus Carmovirus in the family Tombusviridae. To determine whether SYMMV is present in the United States, single leaflets were collected without regard for symptoms from 7 to 10 plants in each of 136 plots in August 2008 from a research field in Stoneville, MS that contained 16 plant introductions (including five from Korea) and 'Williams 82'. Samples were grouped into 10 pools of 100 leaves from which total RNA was extracted with the Qiagen RNeasy Plant Mini Kit (Germantown, MD), reverse transcribed, and amplified with SuperScript III Platinum SYBR Green One-Step Quantitative Real-time Reverse Transcriptase-PCR Kit (Invitrogen, Carlsbad, CA) and two pairs of oligonucleotide primers (5'-CGTCTGCCAGGGTTTAATACTA-3', and 5'-GATTAGCATGTCAGGGTGGTCG-3'; and 5'-ACTGAGTCCCCTGCTTAT-3' and 5'-CATCACTAGCGTCYGGATCA-3') that were designed from regions conserved between SYMMV and Cowpea mottle virus (CPMoV; a related and seed-transmitted carmovirus). Six 100-leaflet pools were positive with both primer sets and four pools were negative with both primer sets. Total RNA extracted from one positive pool was reverse transcribed using SuperScript II reverse transcriptase and a primer complementary to nt 4,000 to 4,009 of the SYMMV genome and amplified using iProof DNA polymerase (Bio-Rad, Hercules, CA) as two overlapping DNA fragments using primers corresponding to nt 1 to 21 and complementary to nt 3,483 to 3,508 and corresponding to nt 3,366 to 3,391 and complementary to nt 4,000 to 4,009. DNA fragments were sequenced using a BigDye Terminator Cycle Sequencing Kit and ABI 3730XL capillary sequencers (Applied Biosystems, Foster City, CA). The 4,009-nt sequence of the Mississippi SYMMV isolate (GenBank Accession No. FJ707484) was 96% identical to the Korean SYMMV isolate and 65% identical to CPMoV. Because of the sampling techniques used, it was not possible to associate SYMMV-positive plants with disease symptoms in Mississippi. To our knowledge, this is the first report of SYMMV in North America. Reference: (1) M. Nam et al. Online publication. doi:10.1077/s00705-009-0480. Arch. Virol., 2009.

Nucleotide sequence and genomic organization of a newly identified member of the genus Carmovirus, soybean yellow mottle mosaic virus, from soybean

The viral genome of soybean yellow mottle mosaic virus (SYMMV) from infected soybean (Glycine max) in Korea was cloned and sequenced. The complete monopartite single-stranded RNA genome of SYMMV consists of 4009 base pairs with six putative open reading frames and includes 5'- and 3'-untranslated regions of 39 and 229 nucleotides, respectively. The nucleotide and coat protein sequences of SYMMV share the highest sequence identity with those of cowpea mottle virus. Based on its genomic organization, its predicted amino acid sequence, and its phylogenetic relatedness to known carmoviruses, we report that SYMMV is a new member of the genus Carmovirus in the family Tombusviridae.