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Complete genome sequences of 22 isolates of Cucurbit aphid-borne yellows virus (CABYV), collected from melon plants showing yellowing symptom in Korea during the years 2013–2014, were determined and compared with previously reported CABYV genome sequences. The complete genomes were found to be 5,680–5,684 nucleotides in length and to encode six open reading frames (ORFs) that are separated into two regions by a non-coding internal region (IR) of 199 nucleotides. Their genomic organization is typical of the genus Polerovirus. Based on phylogenetic analyses of complete nucleotide (nt) sequences, CABYV isolates were divided into four groups: Asian, Mediterranean, Taiwanese, and R groups. The Korean CABYV isolates clustered with the Asian group with > 94% nt sequence identity. In contrast, the Korean CABYV isolates shared 87–89% sequence identities with the Mediterranean group, 88% with the Taiwanese group, 81–84% with the CABYV-R group, and 72% with another polerovirus, M.. Recombination analyses identified 24 recombination events (12 different recombination types) in the analyzed CABYV population. In the Korean CABYV isolates, four recombination types were detected from eight isolates. Two recombination types were detected in the IR and P3–P5 regions, respectively, which have been reported as hotspots for recombination of CABYV. This result suggests that recombination is an important evolutionary force in the genetic diversification of CABYV populations.

The Sweet potato chlorotic fleck virus (SPCFV), of the genus Carlavirus (family Betaflexiviridae), was first detected as one of several viruses infecting sweet potatoes (Ipomea batatas L.) in Korea. Out of 154 sweet potato samples collected in 2012 that were showing virus-like symptoms, 47 (31%) were infected with SPCFV, along with other viruses. The complete genome sequences of four SPCFV isolates were determined and analyzed using previously reported genome sequences. The complete genomes were found to contain 9,104-9,108 nucleotides, excluding the poly-A tail, containing six putative open reading frames (ORFs). Further, the SPCFV Korean isolates were divided into two groups (Group I and Group II) by phylogenetic analysis based on the complete nucleotide sequences; Group I and Group II had low nucleotide sequence identities of about 73%. For the first time, we determined the complete genome sequence for the Group II SPCFV isolates. The amino acid sequence identity in coat proteins (CP) between the two groups was over 90%, whereas the amino acid sequence identity in other proteins was less than 80%. In addition, SPCFV Korean isolates had a low amino acid sequence identity (61% CPs and 47% in the nucleotide- binding protein [NaBp] region) to that of Melon yellowing-associated virus (MYaV), a typical Carlavirus.

In plant virus ecology, weeds are regarded as wild reservoirs of viruses and as potential sources for insect-mediated transmission of viruses. During field surveys in 2013-2014, three Leonurus sibiricus plants showing virus-like symptoms were collected from pepper fields in Daegu, Seosan, and Danyang in Korea. Molecular diagnosis assays showed that the collected L. sibiricus samples were infected with either Tomato spotted wilt virus (TSWV), Pepper mild mottle virus (PMMoV), or Beet western yellow virus (BWYV), respectively. Since this is the first identification of TSWV, PMMoV, and BWYV from L. sibiricus, complete genome sequences of three virus isolates were determined to examine their phylogenetic relationships with the previously reported strains and isolates. Phylogenetic analyses performed using full genome sequences of the viruses showed the isolates of TSWV and PMMoV obtained from L. sibiricus are closely related to the pepper isolates of the corresponding viruses. Our results suggest that L. sibiricus could act an alternative host and reservoir of viruses that cause damages in pepper fields.

The infectious full-length cDNA clone of zucchini yellow mosaic virus (ZYMV) isolate PA (pZYMV-PA), which was isolated from pumpkin, was constructed by utilizing viral transcription and processing signals to produce infectious in vivo transcripts. Simple rub-inoculation of plasmid DNAs of pZYMV-PA was successful to cause infection of zucchini plants (Cucurbita pepo L.). We further engineered this infectious cDNA clone of ZYMV as a viral vector for systemic expression of heterologous proteins in cucurbits. We successfully expressed two reporter genes including gfp and bar in zucchini plants by simple rub-inoculation of plasmid DNAs of the ZYMV-based expression constructs. Our method of the ZYMV-based viral vector in association with the simple rub-inoculation provides an easy and rapid approach for introduction and evaluation of heterologous genes in cucurbits.

Melon necrotic spot virus (MNSV) was recently identified on watermelon (Citrullus vulgaris) in Korea, displaying as large necrotic spots and vein necrosis on the leaves and stems. The average occurrence of MNSV on watermelon was found to be 30–65% in Hapcheon and Andong City, respectively. Four isolates of the virus (MNSV-HW, MNSV-AW, MNSV-YW, and MNSV-SW) obtained from watermelon plants in different areas were non-pathogenic on ten general indicator plants, including Chenopodium quinoa, while they infected systemically six varieties of Cucurbitaceae. The virus particles purified by 10–40% sucrose density gradient centrifugation had a typical ultraviolet spectrum, with a minimum at 245 nm and a maximum at 260 nm. The morphology of the virus was spherical with a diameter of 28–30 nm. Virus particles were observed scattered throughout the cytoplasm of watermelon cells, but no crystals were detected. An ELISA was conducted using antiserum against MNSV-HW; the optimum concentrations of IgG and conjugated IgG for the assay were 1 μl/ml and a 1:8,000–1:10,000 dilutions, respectively. Antiserum against MNSV-HW could capture specifically both MNSV-MN from melon and MNSV-HW from watermelon by IC/RT-PCR, and they were effectively detected with the same specific primer to produce product of 1,172 bp. The dsRNA of MNSV-HW had the same profile (4.5, 1.8, and 1.6 kb) as that of MNSV-MN from melon. The nucleotide sequence of the coat protein of MNSV-HW gave a different phylogenetic tree, having 17.2% difference in nucleotide sequence compared with MNSV isolates from melon.

The incidence of Broad bean wilt virus 2 (BBWV2) on red pepper was investigated using the samples obtained from 24 areas of 8 provinces in Korea. Two hundred and five samples (79%) out of 260 collected samples were found to be infected with BBWV2. While the single infection rate of BBWV2 was 21.5%, the co-infection rate of BBWV2 with Cucumber mosaic virus, Pepper mottle virus, Pepper mild mottle virus and/or Potato virus Y was 78.5%. To characterize the genetic diversity of BBWV2 Korean isolates, 7 isolates were fully sequenced and analyzed. Phylogenetic analyses revealed that BBWV2 isolates could be divided largely into two groups as Group I and Group II. Based on the partial sequence analyses, 153 selected BBWV2 isolates were subgrouped into GS-I (21.6%), GS-II (3.9%) and GS-III (56.9%). BBWV2 GS-III, which was predominant in Korea, appears to be a new combination between Group I RNA-1 and Group II RNA-2. Viral disease incidence of BBWV2 on red pepper was under 2% before 2004. However, the incidence was increased abruptly to 41.3% in 2005, 58.2% in 2006 and 79% in 2007. These rapid increases might be related with the emergence of new combinations between BBWV2 groups.

The full-genome sequences of fourteen isolates of Broad bean wilt virus 2 (BBWV2), collected from broad bean, pea, spinach, bell pepper and paprika plants in Korea during the years 2006–2012, were determined and analyzed comparatively along with fifteen previously reported BBWV2 genome sequences. Sequence analyses showed that RNA-1 and RNA-2 sequences of BBWV2 Korean isolates consisted of 5950–5956 and 3568–3604 nucleotides, respectively. Full-length genome sequence-based phylogenetic analyses revealed that the BBWV2 Korean isolates could be divided into three major groups comprising GS-I (isolates BB2 and RP7) along with isolate IP, GS-II (isolates BB5, P2, P3 and RP3) along with isolate B935, and GS-III including 16 BBWV2 Korean isolates. Interestingly, GS-III appears to be newly emerged and predominant in Korea. Recombination analyses identified two recombination events in the analyzed BBWV2 population: one in the RNA-1 of isolate K and another one in the RNA-2 of isolate XJ14-3. However, no recombination events were detected in the other 21 Korean isolates. On the other hand, out of 29 BBWV2 isolates, 16 isolates were found to be reassortants, of which each RNA segment (i.e. RNA1 and RNA2) was originated from different parental isolates. Our findings suggested that reassortment rather than recombination is a major evolutionary force in the genetic diversification of BBWV population in Korea.

Tomato yellow leaf curl virus (TYLCV), a member of genus Begomovirus, was isolated in Korea in 2008. We sequenced and analyzed the DNA-A of 51 TYLCV isolates from Korea, and 13 of the TYLCV isolates were selected as type representatives of TYLCV from six Korean provinces. The 13 TYLCV isolates were classified into Korea Group 1 (KG1, nine isolates) and Korea Group 2 (KG2, four isolates) based on the results of phylogenetic analysis and genome size (2774 and 2781 nucleotides, respectively). A recombination detection program 3 (RDP3) revealed two recombinations between the TYLCV Korea isolates and other TYLCV isolates [Thailand (AF206674), Iran (AJ132711), and Israel (X76319)]. TYLCV Jeju isolate was characterized by two recombination events (E1 and E2) caused by the presence of E1 in ORF V1 and C3, which may seem to be the mutations of the high nucleotide transversion and transition rate. Collectively, our results suggest that the occurrence of nucleotide transversions and transitions in TYLCV DNA-A might have induced novel recombination events within the TYLCV Korea isolates.

In order to detect quarantine plant viruses, we developed reverse transcription-polymerase chain reaction (RT-PCR) primer pairs for five single-stranded (ss) plant RNA viruses that are not currently reported in Korea but could be potential harmful plant viral pathogens. Three viruses such as Chilli veinal mottle virus (ChiVMV), Colombian datura virus (CDV), and Tobacco etch virus (TEV) belong to the genus Potyvirus while Chrysanthemum stem necrosis virus (CSNV) and Iris yellow spot virus (IYSV) are members of the genus Tospovirus. To design RT-PCR primers, we used reported gene sequences corresponding to the capsid protein and polyprotein for ChiVMV, CDV, and TEV while using nucleocapsid protein regions for CSNV and IYSV. At least two different primer pairs were designed for each virus. Fifteen out of 16 primer pairs were successfully applied in detection of individual quarantine virus with high specificity and efficiency. Taken together, this study provides a rapid and useful protocol for detection of five quarantine viruses.

Department of Agricultural Biology, National Academy of Agricultural Science, Rural Development Administration, Suwon 441-707, Korea(Received on March 22, 2011; Accepted on April 11, 2011)Our previous sequence and phylogenetic analyses ofthe Korean Rice stripe virus (RSV) suggested possiblegenetic reassortment of RNA segments, but whether thisRNA variation contributed to the recent RSV outbreaksin Korea is yet unclear. To further clarify these RSV-RNA segment variations, we developed a reverse tran-scription-polymerase reaction/restriction enzyme (RT-PCR/RE) analysis-based method. We identified fiveREs, including DraI, EcoR1, NdeI/AseI, and SpeI, thatcould differentiate RSV RNA 1–4 subtypes, respectively.Our RT-PCR/RE results provided a clear pattern ofRNA reassortment, i.e., different groups of isolates havingtheir RNA segments derived from two to three differentRSV ancestors, such as from Eastern and SouthwesternChinese or Japanese M and T isolates. We also foundthat the migratory small brown planthopper from EasternChina caught by aerial net traps that possesses RSV-RNA3 genotypes corresponds mainly to Eastern China,with a few for Southwestern China based on RT-PCR/RE, sequence and phylogenetic analyses, indicating thatRSV populations in Eastern China may also have strongRNA variation. The development of an RE analysis-based method proved a useful epidemiological tool forrapid genotyping and identification of mixed infectionsby RSV strain and by different subtype.Keywords : genotyping, genetic structure, phylogeneticrelationships, restriction enzyme analysis, Rice stripe virusThe genome of Rice stripe virus (RSV), the prototypemember of the genus Tenuivirus, consists of four ssRNAs,with a total genome size of about 23 kb (Fig. 1; Toriyamaand Tomaru, 1995). RNA1 is the largest segment, havingnegative sense, while the other three segments are ambisense,whereby a single protein is encoded at the 5 proximal endin viral (v) and viral complementary (vc) RNA strands(Hamamatsu et al., 1993; Takahashi et al., 1993; Zhu et al.,1991, 1992). The RSV genome has a total of seven proteinsand most of their functions are known, except for NS2coded in vRNA2. The function of proteins coded in vcRNA1,vcRNA2, vcRNA3, and vRNA4 have long been known asRNA-dependent RNA polymerase (RdRp; Toriyama et al.,1994), glycoprotein-membrane protein (Takahashi et al.,1993), nucleocapsid protein, and noncapsid protein ordisease-specific protein (Kakutani et al., 1990; Zhu et al.,1992), respectively. However, proteins coded in vRNA3and vcRN4 were only recently reported as suppressors ofposttranscriptional gene silencing (PTGS; Hemmes et al.,2007) and movement protein (Xiong et al., 2008), respec-tively. RSV-infected plants usually show chlorotic stripes on theleaves and stunted growth, while severely infected seedl-ings are lethal. The virion morphology of the causal virushas circular filament and is actively and persistently trans-mitted by the small brown planthopper (SBPH) Laodelphaxstriatellus (Koganezawa, 1977). RSV outbreaks have alsooccurred in China, Japan, Taiwan, and the former USSR(Hibino, 1996). For insect transmitted viruses like RSV, its spread is mainlydependent on vector migration. In a previous study on theNilaparvata lugens (Stal), migration processes in Korea usingthe boundary layer atmospheric model and a geographicinformation system showed that the main source of insectsimmigrated into South Korea in the early part of June werefrom the Eastern part of China (Zhu et al., 2000). China andJapan are in close proximity to Korea, and reports show thatChina has a longer history of RSV outbreaks than Japan (Weiet al., 2009). During 2007−2009, RSV had burgeoning incidences thatcaused significant yield losses, posing an enigma to ricegrowers and many rice scientists in South Korea. The cause

Rice stripe virus (RSV) is one of serious epidemic pathogens for rice species grown in many Asian countries. Therefore, it is necessary to produce a diagnostic detection kit applicable in fields for RSV detection. In this study, RSV proteins that were derived from recombinant proteins and synthetic polypeptides as antigens were generated and were raised in rabbits for antiserum production. Among seven proteins in RSV, genes that code for NCP and NS3 proteins were cloned and subcloned into vector carrying His-tag protein and were expressed in E. coli. Of two recombinant proteins, only anti-NCP displayed stable hybridization signals in western blot analysis. Alternately, synthetic RSV polypeptides for CP, NCP, NS3 and NSvc4 we also generated and only antibodies against CP and NCP were very effective to detect RSV in both RSV infected rice and weed plants. However, antibodies against NS3 and NSvc4 showed weak specific bands as well as strong non-specific background due to the difference of viral proteins produced in the infected leaves. In summary, the antibodies generated against RSV proteins produced in this study will be useful for various assays such as for RSV diagnostic detection, immunoprecipitation, protein purification, and western blot analysis.

A tobamovirus, Ribgrass mosaic virus (RMV), was identified newly from chinese cabbage (Brassica campestris L. pekinensis) in Korea. Virus disease incidence of RMV on chinese cabbage was 37.9% in alpine area on August in 1993. RMV induced the symptoms of necrotic ring spots, necrotic streak on midrib and malformation. RMV, Ca1 and Ca3 isolate, could infect 35 species out of 45 plants including Chenopodium amaranticolor. Physical properties of RMV Ca1 isolate were very stable as 10.8 over for dilution end point, for temperature inactivation point and 18 weeks for longevity in vitro. RMV had the soil transmission rate of 75.0% for the chinese cabbages, `Chunhawang` and `Seoul` cultivars. The purified virions of RMV had the typical ultraviolet absorption spectrum of maximum at 260 nm and minimum at 247 nm. RMV of Ca1 isolate was related serologically with antisera of Tobacco mosaic virus (TMV)-Cym, TMV-O and Pepper mottle virus, but not related with antiserum of Odontoglossum ring spot virus. coat protein gene of RMV-Ca1, sized 473 nucleotides, encoded 158 amino acid residues. Nucleotide identity of RMV-Ca1 CP gene was 96.4% with RMV-Shanghai (GenBank accession No. of AF185272) from China and 96.0% with RMV-Impatiens (GenBank accession No. of AM040974) from Germany. Identity of amino acids between RMV-Ca1 and the two RMV isolates was 96.8%. Specific three primers were selected for rapid and easy genetic detection of RMV using Virion Captured (VC)/RT-PCR method.

Department of Plant Medicine, Chungbuk National University, Cheongju 361-763, Korea(Received on December 21, 2009; Accepted on February 15, 2010)A virus isolate causing symptoms of yellow mosaic, fernleaves, malformation and plant necrosis on Rudbeckiabicolor was prevalent around Pyeongchang area inKorea. The causal virus was identified as Cucumbermosaic virus (CMV) using characteristics from bio-logical, serological and molecular analyses and namedas CMV-Rb. CMV-Rb caused mosaic on Nicotianabenthamiana, N. tabacum, Capsicum annuum, and Lyco-persicon esculentum. However, typical local lesions didnot develop on inoculated Pisum sativum, Cucurbitamoschata, Datura stramonium and Tetragonia expansaplants. Full-length genome sequences of CMV-RbRNAs 1, 2 and 3 were obtained using 12 primer pairs byRT-PCR analysis. The genome of CMV-Rb RNA seg-ments 1, 2, and 3 consists of 3363nt, 3049nt, and 2214ntin length, respectively. In order to ascertain their taxo-nomic identity, nucleotide and the deduced amino acidsequence analyses RNAs 1, 2 and 3 of CMV-Rb isolateswere conducted with previously reported sequences ofCMV strains and/or isolates. CMV-Rb RNAs showedabout 90 to 99% sequence identity to those of subgroupI strains suggesting that CMV-Rb is more closely relat-ed to CMV isolates belong to subgroup I. To our know-ledge, this is the first report of CMV on Rudbeckiabicolor in Korea.Keywords : CMV-Rb, phylogenetic analyses, Rudbeckiabicolor, subgroup ICucumber mosaic virus (CMV), the type member of thegenus Cucumovirus, infects more than 1,000 species ofplants and induces the typical mosaic symptoms in manyhost plants. Some of the intermediate symptoms, however,include blight, fernleaf, ringspot, and stunt. In Korea, atleast 109 natural host plant species has been reported, i.e.,20 in upland crops, 20 in vegetable crops, 28 in floral crops,acacia in wood, 40 in wild plants (List of plant disease inKorea, 2004, The Korean Society of Plant Pathology).Recently, CMV infections were also reported on Hydrangeamacrophylla (Lee et al., 2001), water chickweed (Choi etal., 2004), Isodon inflexus Kudo, Jeffersonia dubia Benth,Phryma leptostachya var. asiatica Hara (Lee et al., 2008).However, no natural outbreaks by CMV have been reportedon Rudbeckia bicolor, but Bidens mottle virus (BiMoV)was only identified (Brunt et al., 1996; Choi, 2001; Jin,2003; Lee, 1981; Lee et al., 2003; Logan et al., 1984).The genome of CMV consists of three genomic RNAs(RNA 1, 2 and 3; Roossinck, 2001). In infected host plants,it also produces two subgenomic RNAs (4 and 4A; Palukaitiset al., 1992). Based upon biological, serological, and, mole-cular biological characteristics of CMV isolates, they wereclassified into two subgroups, i.e., subgroup I and II (Owenand Palukaitis, 1988). The nucleotide sequence identitybetween subgroup I and II isolates range from 69 to 77%,while showing above 90% nucleotide sequence identitywithin each subgroup isolates. More detailed nucleotidesequence analyses, especially with the coat protein (CP)and 5' nontranslated region (NTR) of RNA 3 further sug-gested subdivision of subgroup I into subgroups IA and IB(Roossinck et al., 1999). This subgrouping was more clear-ly supported from the analysis of nucleotide sequences of1a and 3a open reading frames (ORFs) than those of the 2aand CP ORFs (Roossinck, 2002). In this paper, we reportthe biological and serological characteristics as well ascomplete nucleotide sequence analyses of CMV-Rb isolate.We believe this is the first report of natural CMV infectionon Rudbeckia bicolor in Korea.Pinewood coneflower (R. bicolor), family Asteraceae, iswidely grown as an ornamental crop and a wildflower. In2005, we could easily observe yellow mosaic, sometimes

The complete genome sequences of RNA3 and RNA4 of the 13 different Rice stripe virus (RSV) isolates were determined and characterized in this study to address the possible causes of the recent re-emergence of RSV that affected many rice fields in Korea. The genome size of each RNA segment varied among isolates and significant differences were observed in the intergenic region. There was up to 4% average divergence in the RNA4 nucleotide sequence among 13 Korean isolates and only 1.4% in the RNA3. Phylogenetic relationships among different Korean isolates revealed that there were at least 2 types of RNA3 and 4 distinct types of RNA4 genomes present in Korea. However, Korean isolates with one type of RNA3 predominate over the other while the occurrences of the RSV Korean isolates with the 4 types of RNA4 genome were not correlated to specific geographical areas. Results further indicate that RNA4 had diverged more than RNA3 and these differences in accumulation of mutations in the individual RNA segments indicate that genetic reassortment were likely to contribute to the genetic divergence in the 13 Korean isolates. All of the Korean-RNA3 sequences except for one isolate grouped with Chinese isolates (JY and Z). In contrast, the RNA 4 sequences segregated together with either Chinese (JY and Z) and Japanese (M and T) isolates but genetic relationships of Korean isolates- RNAs 3 and 4 segments to Chinese-Y isolate were low. Altogether, these results suggest that the occurrence of mixtures of RNAs 3 and 4 genotypes in the natural population of RSV may have contributed to the sudden outbreak in Korea.

An infectious full-length clone of Soybean mosaic virus (SMV) strain G5H was constructed under the control of the cauliflower mosaic virus 35S promoter. The cloned SMV G5H established infections upon simple rub-inoculation of soybean leaves with intact plasmid DNA. We demonstrated that this SMV G5H infectious DNA clone caused typical characteristic symptoms and virulence of SMV strain G5H in twelve tested soybean cultivars. Soybean cultivars Lee74, Somyungkong and Sowonkong developed systemic mosaic symptom while Kwanggyo, Taekwangkong, Hwangkeumkong and Geumjeongkong-l showed systemic necrosis. In contrast, Geumjeongkong-2, Jinpumkong-2, L29, V94-5152 and Ogden showed resistant response against SMV-G5H infection. We also determined full-length sequence of cloned SMV-G5H. The phyogenetic analyses reveal that SMV-G5H is most closely related to SMV-G5, and support that SMV-G5H might be derived from SMV-G5 by recombination rather than mutation.

The incidence and occurrence of virus infecting paprika (Capsicum annuum var. grossum) in Jeonnam province, the main areas of cultivation in Korea is undetermined. In this study, a total of 1,020 samples with virus-like symptoms were collected in Jeonnam province during summer season for 3 consecutive years (2002-2005) and were tested using enzyme linked immunosorbent assay (ELISA). Results showed that Pepper mottle virus (PepMoV), Broad bean wilt virus (BBWV), and Cucumber mosaic virus (CMV) were found to be the most prevalent viruses with a 3-year average percent incidence of 41.3, 19.8, and 4.4 respectively. Mixed infection with more than two viruses was also found with 3.5%, 17.0%, and 8.3%, respectively. Symptoms of these virus diseases were not evident at the seedling stage but slowly appeared at the transplanting stage and increased to the middle stage (4-5 months after transplanting) during the 3-year cultivation periods. Symptom appearance of infected plants however varied largely with transplanting time. Those plants transplanted from November to January were found to be infected with viruses in June, whereas symptoms appeared with in a month those plants transplanted from June to August. There were differences in the virus incidence from primary factor such as district, type of green house and variety, but these were not statistically significant (data not shown). Recommended control measures of paprika against these viruses is also discussed in this paper.

The transient and rapid expression system of a foreign protein in planta is a very useful technique in biotechnology application. We have investigated optimum condition of Agrobacterium-infiltration technique in which expression level of foreign proteins were maximized without detrimental effects on plants using GFP and Cucumber mosaic virus 2b protein, which is known as an enhancer of gene expression and a suppressor of post-transcriptional gene silencing(PTGS). The optimum expression level of both RNA and protein of GFP with minimum leaf impairment was obtained at

A peculiar virus-like disease of tomato showing yellow mosaic and necrotic spots on leaves and necrosis on veins, petioles and stems was observed at the Tomato Experimental Station (TES), Buyeo, Chungcheongnamdo, Korea. The disease incidence at TES fields ranged from 21 to 35% infecting different tomato cultivars. For this reason, to identify the virus infecting tomato and to characterize the virus based on biology, serology, cytology and at molecular level. Here, leaf samples were randomly collected from different infected tomato cultivars at TES fields and greenhouses and tested by ELISA using Pepper mottle virus (PePMoV) and Tomato mosaic virus (ToMV) antisera. Infected saps were mechanically inoculated in different host plants to test for pathogenicity, symptomatology and host ranges. Infected tissues and ultrathin sections were examined by electron microscopy. Finally, putative coat protein and 3`-untranslated region (CP/3`-UTR) fragment was amplified and cloned for sequence determination and analyzed its genetic relationship to existing PepMoV and PVY sequences at the Genbank. Results showed 69% of the samples were positive with PepMoV, 13% with ToMV and 19 % were doubly infected with PepMoV and ToMV. Symptoms greatly varied from different host plants inoculated with tomato leaf sap infected with PepMoV alone and discussed in detailed in this paper. Electron microscopy from infected tissues showed filamentous particles of 720-750nm in length, a typical morphology and size of PepMoV. In addition, cylindrical inclusion bodies, pinwheels, scrolls and laminates with masses of fibrillar inclusions were also found in ultrathin sections. Alignment of the sequences of the CP/3`-UTR revealed >96% sequence identity with PepMoV and only

Interactions between viral proteins and host proteins are essential for virus replication. Especially, translation of viral genes completely depends on the host machinery. In potyviruses, interactions of genome-linked viral protein (VPg) with host translation factors including eIF4E, eIF(iso)4E, and poly(A)-binding protein (PABP) has previously been characterized. In this study, we investigated interactions between Soybean mosaic virus (SMV) viral proteins and host translation factors by yeast two-hybrid system. SMV VPg interacted with eIF4E, eIF(iso)4E, and PABP in yeast two-hybrid system, while SMV helper component proteinase (HC-pro) interacted with neither of those proteins. The interaction between SMV NIb and PABP was also detected. These results are consistent with those reported previously in other potyviruses. Interestingly, we found reproducible and specific interactions between SMV coat protein (CP) and PABP. Deletion analysis showed that the region of CP comprising amino acids 116 to 206 and the region of PABP comprising amino acids 520 to 580 are involved in CP/PABP interactions. Soybean library screening with SMV NIb by yeast two-hybrid assay also identified several soybean proteins including chlorophyll a/b binding preprotein, photo-system I-N subunit, ribulose 1,5-biphosphate carboxylase, ST-LSI protein, translation initiation factor 1, TIR-NBS type R protein, RNA binding protein, ubiquitin, and LRR protein kinase. Altogether, these results suggest that potyviral replicase may comprise a multi-protein complex with PABP, CP, and other host factors.

A new virus-like disease of tomato showing chlorotic spots, malformation and necrosis on leaves, and chlorotic blotching, rings, and necrosis on fruits was observed around Sacheon, Gyeongsangnam-do, Korea in 2004. Host range analysis could not differentiate 4 field isolates collected from tomatoes showing different symptoms but identified them as Tomato bushy stunt virus (TBSV). TBSV-tsf2 isolate induced symptoms in indicator plants similar to those caused by the TBSV-C, -S and -Nf. As the isolate could not systemically infect Chenopodium quinoa, the isolate might belong to the previously described TBSV-S isolate. TBSV-tsf2 isolate caused similar cytological alterations that were similar to that generally caused by previously reported TBSV isolates. TBSV-tsf2 isolate, however, could be considered to belong to new strain of TBSV because masses of small electron-dense patches that were not observed from the previously described TBSV. The complete nucleotide sequences of the genomic RNA of 4739 nt excluding non-translated sequences at both termini have been determined and compared to sequences of other TBSV strains. The complete nucleotide sequence identity among TBSV isolates was 98.9% to 99.7%, and to the other tombusviruses ranged from 80.8% to 94.9%. Comparison of the amino acid sequences all five ORFs with those of other TBSV strains shows a similar genomic organization, and high percentage of amino acid sequence homology with TBSV-Nf than TBSV-S isolate. Since the TBSV symptoms were only observed in Sacheon fields where imported seeds from Japan were planted, the TBSV incidence probably caused by the planting contaminated tomato seeds and thus require more through quarantine procedure to prevent settlement of TBSV in Korea. Altogether, these results support that the Korean isolate of TBSV infecting tomato might be new strain.

The occurrence and relative incidence of viruses including Cucumber mosaic virus (CMV), Zucchini yellow mosaic virus (ZYMV), Papaya rings pot virus (PRSV), and Watermelon mosaic virus (WMV), Cucumber green mottle mosaic virus (CGMMV), Kyuri green mottle mosaic virus (KGMMV), and Melon necrotic spot virus (MNSV) were surveyed from main melon (Cucumis melo L.) production areas in Jeonnam province during 2000-2002. Virus disease incidences of melon cultivating fields were 0% and 11% in spring and fall 2000; 40%, 2.1%, and 8.8% in spring, summer, and fall 2001; and 6.3 % in spring 2002 in main cultivated areas in Jeonnam province, respectively. Field disease incidences of melon virus infections were 0% and 18.8% in spring and fall 2000; 50%, 38.5%, and 82.6% in spring, summer, and fall 2001; and 47.4% in spring 2002, respectively. Total of 101 melon samples showing typical disease symptoms were collected from 2000 to 2002 and tested for virus infection by RT-PCR. Potyvirus-specific DNA fragments for WMV, ZYMV, and PRSV were amplified from 46, 5, and 4 samples, respectively. MNSV specific DNA fragment was amplified from 18 samples. CMV-specific DNA fragment was detected from only 3 samples.

Sweet potato feathery mottle virus(SPFMV) is one of the most prevalent viruses infecting sweet potatoes and occurs widely in sweet potato cultivating areas in Korea. To assess their genetic variation, a total of 28 samples infected with SPFMV were subjected to restriction fragment length polymorphism(RFLP) analysis using DNAs amplified by RT-PCR with specific primer sets corresponding to the coat protein(CP) region of the virus. The similarity matrix by UPGMA procedure indicated that 28 samples infected with SPFMV were classified into three groups based on the number and size of DNA fragments by digestion of CP-encoding regions with 7 enzymes including SalI, AluI, EcoRI, HindIII, FokI, Sau3AI, and DraI bands. Four primer combinations out of 5 designed sets were able to differentiate SPFMV and sweet potato virus G infection, suggesting that these specific primers could be used to differentiate inter-groups of SPFMV. Sequence analysis of the CP genes of 17 SPFMV samples were 97-99% and 91-93% identical at the intra-group and inter-groups of SPFMV, respectively. The N-terminal region of the CP is highly variable and examination of the multiple alignments of amino acid sequences revealed two residues(residues 31 and 32) that were consistently different between SPFMV-O and SPFMV-RC.

Sweet potatoes (Ipomea batatas L.) are grown extensively, in tropical and temperate regions, and are important food crops worldwide. In Korea, potyviruses, including Sweet potato feathery mottle virus (SPFMV), Sweet potato virus C (SPVC), Sweet potato virus G (SPVG), Sweet potato virus 2 (SPV2), and Sweet potato latent virus (SPLV), have been detected in sweet potato fields at a high (~95%) incidence. In the present work, complete genome sequences of 18 isolates, representing the five potyviruses mentioned above, were compared with previously reported genome sequences. The complete genomes consisted of 10,081 to 10,830 nucleotides, excluding the poly-A tails. Their genomic organizations were typical of the Potyvirus genus, including one target open reading frame coding for a putative polyprotein. Based on phylogenetic analyses and sequence comparisons, the Korean SPFMV isolates belonged to the strains RC and O with >98% nucleotide sequence identity. Korean SPVC isolates had 99% identity to the Japanese isolate SPVC-Bungo and 70% identity to the SPFMV isolates. The Korean SPVG isolates showed 99% identity to the three previously reported SPVG isolates. Korean SPV2 isolates had 97% identity to the SPV2 GWB-2 isolate from the USA. Korean SPLV isolates had a relatively low (88%) nucleotide sequence identity with the Taiwanese SPLV-TW isolates, and they were phylogenetically distantly related to SPFMV isolates. Recombination analysis revealed that possible recombination events occurred in the P1, HC-Pro and NIa-NIb regions of SPFMV and SPLV isolates and these regions were identified as hotspots for recombination in the sweet potato potyviruses.

In 2003, a survey of sweet potato virus disease was carried out in seed boxes as well as in various sweet potato fields. Virus infection rate was 5~100% and 100% at seed boxes and fields, respectively. No relationship of the disease incidence and severity was observed between sweet potato cultivating areas and cultivars. A total of 179 samples were collected and analyzed based on serological, electron microscopic and molecular properties. Field-grown sweet potatoes were examined to inspect 8 different viruses using NCM-ELISA, resulting that 30% of sweet potato was infected by one virus, whereas 70% was by more than 2 viruses. However, RTPCR using primers selected for seven viruses, such as Sweet potato feathery mottle virus (SPFMV) revealed that of one-hundred seventy-nine tested; 71 of SPFMV, 29 of SPGV, 19 of SPFMV+SPGV, 1 of SPFMV+ SwPLV, 1 of SPFMV+SPLCV, 2 of SPFMV+SPGV+ SwPLV, 6 of SPFMV+SPGV+SPLCV, 2 of SPFMV+ SPGV+SwPLV+SPLCV and 48 of unknown viruses were identified from the field samples. In root, viral diseases were severer in Yeoju than in Mokpo Experiment Station and infection rate was much different depending on sweet potato cultivars.

Disease incidences of cucumber virus diseases in Jeonnam province were 52.5%, 16.1%, 35.2%, and 50.9% in 1999, 2000, 2001, and 2002, respectively. Rod- and flexuous rod-shaped virus particles were observed with the frequencies of 63.2% and 10.5%, respectively from the samples collected in 1999 under EM observation. Rod-shaped virus particles are considered as tobamovirus while flexuous rod shaped particles are considered as potyviruses. To further confirm their nature, total of 312 diseased virus samples were collected from 2000 to 2002, and tested by RT-PCR. Disease incidences of tobamoviruses including Cucumber green mottle mosaic virus and Kyuri green mottle mosaic virus were 48.7% and 3.8%, respectively while those of potyviruses including Zucchini yellow mosaic virus, Papaya ringspot virus, and Watermelon mosaic virus were 15.7%, 9.3%, and 5.1%, respectively. Interestingly, Cucumber mosaic virus was hardly detected. About 5.8% of tested samples were infected with more than one virus. Tobamovirus infection was consistently observed from September to December regardless of planting time, whereas infection of potyviruses was observed in many cucumber cultivating areas where it was planted in September and October.

A virus causing chlorotic ringspot, yellow mosaic and vein clearing symptoms was prevalent on mungbean plants around Taean, Korea. The isolate caused mosaic on Chenopodium quinoa, Nicotiana benthamiana, Phaseolus vulgaris and Vida laba but no symptoms on peanut plants. Inclusion bodies such as scroll, pinwheel and laminated aggregates induced by the virus in the host cells were similar to those produced by members of the Potyvirus subdivision III. Multiple alignment as well as cluster dendrograms of the 709 nucleotide region comprising part of the coat protein gene and 3`untranslated region (UTR) showed that the isolate belongs to the BCMV-PSt subgroup. Altogether, these results support the identification of the causal virus as peanut stripe strain of Bean common mosaic virus (BCMV-PSt).

A virus causing vein banding, sometimes yellow mosaic and rugose symptoms on peanut was prevalent around Suwon, Korea. A survey conducted in the area found disease incidence, depending on cultivar, to range from 79 to . The virus was found to be seed-transmissible in all the five peanut cultivars tested with transmission rates ranging from 2 to . Host range analysis failed to differentiate 9 field isolates collected from different peanuts cultivars showing various symptoms. Inclusion bodies such as scroll, pinwheel and long laminated aggregates induced by the virus in host plant cells were similar to those induced by members of the Potyvirus subdivision III. The virus showed homology with Bean common mosaic virus (BCMV), BCMV-BICMV/AzMV strains and only with Desmodium mosaic virus. Based on biological characterization, electron microscopy and molecular analyses of a Korean isolate (Daewon 1), the virus was identified as peanut stripe strain of BCMV.

Turnip mosaic virus (TuMV) is an infectious viral pathogen on the cruciferous crops, predominantly Chinese cabbage (Brassica campestris subsp. pekinensis) and radish (Raphanus sativus). On the basis of the symptom development in selective differential hosts from indicator host species, Chinese cabbage and Korean radish inbred lines, the representative eight isolates of TuMV were divided into two major groups/or six types. Group I includes Th 1, Ca-ad7, and Cj-ca2-1 isolates, while group II includes the other isolates (rg-pfl, r 9-10, Rhcql-2, Stock and Mustard). According to the molecular phylogenetic analysis, these isolates, however, divided into two groups and two independent isolates. Phylogenetic analysis indicated that four isolates (Tu 1, r9-10, Stock and Rh-cql-2) formed a distinct phylogenetic group, and the other two isolates (Ca-ad7 and Cj-ca2-1) also formed another group. Mustard and rg-pfl isolates did not seem to have any relationship with these two groups. Taken together, these results indicated that virulence differentiation on host plants, molecular phylogenetic analysis of the nucleotide and the deduced amino acid of TuMV coat proteins did not show any relationship. The multi-resistant lines, Wonyae 20026 and BP058 in Chinese cabbage represent valuable genetic materials that can be used for crucifer breeding programs on TuMV resistance, but not in Korean radish.

Peanut stunt virus (PSV) is a member of the genus Cucumovirus inthe family Bromoviridae. Other members of the genus are its typemember Cucumber mosaic virus (CMV) and Tomato aspermy virus(TAV). PSV like other cucumoviruses has a tripartite genome ofpositive strand RNAs, designated RNA1, RNA2 and RNA3, inother decreasing size. PSV is an economically important pathogenand occurs worldwide in legume plants. Since PSV was firstdescribed in the United States in 1966, many strains of PSV havebeen characterized. In Korea, there has been previous record on PSVinfection of peanut, black locast, red goosefoot and white clover(The Korean Society of Plant Pathology 2009)., In Sangju County ofSouth Korea in 2005, a PSV (PSV-K1) was first detected using RT-PCR from naturally infected soybean showing yellow mosaic on theleaves and virus particles were isolated from these infected leaves(Fig. 1A). Purified virus preparations were revealed the presence ofsmall isometric virions of 28 nm in diameter (Fig. 1B).The nucleotide sequence of full-length RNA3 from PSV strainK1 was determined. PSV-K1 RNA3 is 2089 nucleotides (nt)organized into two putative ORFs and 5'- and 3'-untranslatedregions (UTRs) of 52 and 229nt, respectively. Two large openreading frames (ORFs) encoded a putative movement protein (MP)(nt 53 −925) and a coat protein (CP) (nt 1183 −1860) predicted to be a31-kDa protein (P31) and a 25-kDa protein (P25), respectively.ORF3a (MP) is separated from the next ORF3b (CP) by an IR non-coding region (internal region) 257nt in length (nt 926 −1182).Multiple sequence alignments were generated using DNAMAN7.0 (Lynnon Biosoft, Quebec, Canada) on the basis of completenucleotide sequences of PSV RNA3, and a phylogenetic tree wasconstructed by the neighbor-joining algorithm (Fig. 2). Bootstrapanalysis was performed with 1,000 replicates. The resulting tree ofRNA3 revealed that PSV-K1 RNA3 is more closely related to that ofPSV-ER (94.6%) than to those of other cucumoviruses. Percentnucleotide sequence identities of RNA3 from PSV-K1 ranged from58.7 to 94.6% with RNA3 sequences of members of the genusCucumovirus. PSV was first divided into two subgroups based on awide range of comparative analyses, including serology, competi-tion hybridization and sequence comparison (Hu et al., 1997).Recently, the complete nucleotide (nt) sequence of PSV-Mi andPSV-Rp strain was determined, and based on nt sequence diversity,the establishment of a subgroup and was proposed (Yan et al., 2005and Kiss et al., 2008).Phylogenetic analyses of PSV-K1 show clearly that this strain isrelated to representatives of subgroup containing PSV-ER B. ased onthese data, we conclude that PSV is closely related to PSV-ER strainfrom cowpea and it is the first report of PSV on soybean in Korea.