• The Plant Pathology Journal
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• v.36 no.5
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• pp.468-475
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• 2020

Malva vein clearing virus (MVCV) is a member of the Potyvirus species, and has a negative impact on the aesthetic development of Alcea rosea. It was first reported in Germany in 1957, but its complete genome sequence data are still scarce. In the present work, A. rosea leaves with vein-clearing and mosaic symptoms were sampled and analyzed with small RNA deep sequencing. By denovo assembly the raw sequences of virus-derived small interfering RNAs (vsiRs) and whole genome amplification of malva vein cleaning virus SX strain (MVCV-SX) by specific primers targeting identified contig gaps, the full-length genome sequences (9,645 nucleotides) of MVCV-SX were characterized, constituting of an open reading frame that is long enough to encode 3,096 amino acids. Phylogenetic analysis showed that MVCV-SX was clustered with euphorbia ringspot virus and yam mosaic virus. Further analyses of the vsiR profiles revealed that the most abundant MVCV-vsiRs were between 21 and 22 nucleotides in length and a strong bias was found for "A" and "U" at the 5′-terminal residue. The results of polarity assessment indicated that the amount of sense strand was almost equal to that of the antisense strand in MVCV-vsiRs, and the main hot-spot region in MVCV-SX genome was found at cylindrical inclusion. In conclusion, our findings could provide new insights into the RNA silencing-mediated host defence mechanism in A. rosea infected with MVCV-SX, and offer a basis for the prevention and treatment of this virus disease.

• The Plant Pathology Journal
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• v.19 no.3
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• pp.171-176
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• 2003

The complete nucleotide sequences of the genomic RNAs of Soybean mosaic virus strains GS (SMV-G5) and G7H (SMV-G7H) were determined and compared with sequences of other SMV strains. Each viral RNA was determined to be 9588 nucleotides in length excluding the poly (A) tail and contained an open reading frame to encode a polyprotein subsequently processed into up to ten proteins by proteolytic cleavage. Com-parison of the amino acid sequences with those of other SMV strains showed high percentage of amino acid sequence homology with the same genome organization. The nucleotide and the deduced amino acid sequences between SMV-G5 and SMV-G7H were greater than 99% identity. When compared with those of other SMV strains in a phylogenetic analysis of the nucleotide and deduced amino acid sequences, they formed a distinct virus clade showing over 97％ amino acid identity, but were more distantly related to the other potyvirus (44.1-69.6% identity). Interestingly, SMV G7H strain caused a severe mosaic or necrosis symptom in soybean cultivars including Jinpum-1, Jinpum-2, and Sodam, whereas, no symptom was observed in SMV-G5 inoculation. Complete nucleotide sequences of these strains will give clues for determining symptom determinant(s) in future research.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.215-218
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• 2007

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.

• Applied Microscopy
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• v.24 no.2
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• pp.105-114
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• 1994

Comparative ultrastructural studies of sorghum (Sorghum bicolor L. Moench) cultivar (cv.) HOK and cv Pioneer 8680 leaf cells separately infected with maize dwarf mosaic virus (MDMV) strain A and B, respectively, revealed the formation of numerous cylindrical inclusions in both cross and longitudinal sections. The MDMV-A and -B were distinguished by the presence or absence of specific inclusion bodies in the cytoplasm. Electron microscope revealed the presence of pinwheels, bundles, scrolls, and laminated aggregates in Pioneer 8680 sorghum leaf cells infected with MDMV-B while no laminated aggregates were found in cells of HOK sorghum leaf cells infected with MDMV-A. Differences in the ultrastructure of cylindrical inclusions between two strains of MDMV, especially with respect to laminated aggregates, have been morphologically indexed to classify potyviruses into subdivision. The presence of laminated aggregates may be assigned to subdivision III while the absence of laminated aggregates is assigned to subdivision I. These variations of structures associated with cylindrical inclusions appeared virus-specific inductions and may be represented the morphogenesis of inclusion bodies following development of infections.

• The Plant Pathology Journal
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• v.30 no.2
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• pp.183-187
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• 2014

Lettuce mosaic virus (LMV) causes disease of plants in the family Asteraceae, especially lettuce crops. LMV isolates have previously been clustered in three main groups, LMV-Yar, LMV-Greek and LMV-RoW. The first two groups, LMV-Yar and LMV-Greek, have similar characteristics such as no seed-borne transmission and non-resistance-breaking. The latter one, LMV-RoW, comprising a large percentage of the LMV isolates contains two large subgroups, LMV-Common and LMV-Most. To date, however, no Korean LMV isolate has been classified and characterized. In this study, LMV-Muju, the Korean LMV isolate, was isolated from lettuce showing pale green and mottle symptoms, and its complete genome sequence was determined. Classification method of LMV isolates based on nucleotide sequence divergence of the NIb-CP junction showed that LMV-Muju was categorized as LMV-Common. LMV-Muju was more similar to LMV-O (LMV-Common subgroup) than to LMV-E (LMV-RoW group but not LMV-Common subgroup) even in the amino acid domains of HC-Pro associated with pathogenicity, and in the CI and VPg regions related to ability to overcome resistance. Taken together, LMV-Muju belongs to the LMV-Common subgroup, and is expected to be a seed-borne, non-resistance-breaking isolate. According to our analysis, all other LMV isolates not previously assigned to a subgroup were also included in the LMV-RoW group.

• The Plant Pathology Journal
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• v.31 no.1
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• pp.90-96
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• 2015

Garlic generally becomes coinfected with several types of viruses belonging to the Potyvirus, Carlavirus, and Allexivirus genera. These viruses produce characteristically similar symptoms, they cannot be easily identified by electron microscopy (EM) or immunological detection methods, and they are currently widespread around the world, thereby affecting crop yields and crop quality adversely. For the early and reliable detection of garlic viruses, virus-specific sets of primers, including species-specific and genus-specific primers were designed. To effectively detect the twelve different types of garlic viruses, primer mixtures were tested and divided into two independent sets for multiplex polymerase chain reaction (PCR). The multiplex PCR assays were able to detect specific targets up to the similar dilution series with monoplex reverse transcription (RT)-PCR. Seventy-two field samples collected by the Gyeongbuk Agricultural Technology Administration were analyzed by multiplex RT-PCR. All seventy two samples were infected with at least one virus, and the coinfection rate was 78%. We conclude that the simultaneous detection system developed in this study can effectively detect and differentiate mixed viral infections in garlic.

• The Plant Pathology Journal
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• v.21 no.4
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• pp.349-354
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• 2005

A virus isolate collected from infected paprika (Capsicum annuum var. grossum) was characterized as Potato virus Y (PVY) based on biological, serological, cytopathological, and molecular properties. In host range studies, the paprika isolate produced the mosaic symptom on some tobacco, tomato and pepper (Capsicum annuum). A new paprika isolate also infected potato cultivars which is different biological characteristic compared to the other popular potyvirus infecting paprika, Pepper mottle virus (PepMoV). Previously reported PVY strains, $PVY^o$ and $PVY^N$ did not infect pepper and typical PepMoV isolates did not infect potato. Distinctive inclusion patterns of the scroll, pinwheel, long laminated inclusions, and helper components in the cytoplasm of infected cells were also different to those observed by the typical PVY isolate infections. However, the paprika isolate reacted to the monoclonal antibody of $PVY^N$ strain with high absorbance readings. RT-PCR amplification, cloning, and sequencing of the 3' untranslated region and a part of coat protein gene also added additional evidence of the paprika isolate as the $PVY^N$-related isolate. Multiple alignments as well as cluster dendrograms of PVY-paprika isolate revealed close phylogenetic relationship to the $PVY^N$ subgroup. Altogether, these results suggest that a new PVY isolate infecting paprika contained distinct characteristics compared to the other previously described PVY strains with closer relationship to the $PVY^N$ strain.

• The Plant Pathology Journal
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• v.18 no.6
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• pp.313-316
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• 2002

Systemic virus symptoms caused by a Potexvirus were observed on leaves of infected hosta (Hasta spp.) plants cultivated in Seoul, Korea. Symptoms on diseased hosta plants include mosaic, mottle, irregular blotchy patches, and chlorotic spots on or distortion of the leaves. No other viruses, such as Cucumber mosaic virus, Lily symptomless virus, or Potyvirus, were detected from the same plants by electron microscopy and by Western blot and RT-PCR analyses, indicating that they were singly infected by the potexvirus. The symptoms differed among cultivars and species of hosta, and affected the quality of plants for commercialization, as well as, plant growth and flowering of susceptible cultivars. Most of the cultivars and species investigated were susceptible to the virus, while some were not infected by the virus at all. Purified virus particles were of filamentous type with unaggregated forms 540 nm in length, which is a typical potexviral morphology. The virus consisted of a single-stranded RNA molecule of 6 kb long for genome and single component of coat protein (CP) about 27 kDa. The CP strongly reacted with the antiserum against Hosta vims X (HVX), suggesting that the virus is an isolate of HVX. This is the first report of the occurrence and identification of HVX from hosta plants in Korea.

• The Plant Pathology Journal
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• v.27 no.1
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• pp.44-52
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• 2011

Field surveys were conducted in 45 stone fruit orchards in seven districts of Isparta Province located in western Mediterranean region of Turkey important for stone fruit production. Leaf samples were collected from 175 trees showing virus-like symptoms. These samples were first tested by ELISA for five different RNA viruses including Apple mosaic ilarvirus (ApMV), Prunus necrotic ringspot ilarvirus (PNRSV), Prune dwarf ilarvirus (PDV), Plum pox potyvirus (PPV), Apple chlorotic leafspot trichovirus (ACLSV). While no ApMV and PPV infection was found, 46, 24 and 16 samples were tested positive for PDV, ACLSV and PNRSV, respectively, in ELISA showing about 45% of symptomatic trees in the region were infected with at least one of these viruses. In addition, it was found that nine sweet cherry trees were mixed infected with two or three of these viruses and PDV with an infection rate of 26.3% was the most widespread virus in symptomatic trees in western Mediterranean region. Thirty samples were selected and tested by a multiplex RT-PCR (mRT-PCR) for simultaneous detection of these viruses. While PPV was not detected, more than half of the tested 20 samples were individually or mixed infected with ApMV, ACLSV, PNRSV and PDV. The mRT-PCR results were confirmed by detection of these viruses individually in some of the field samples using RT-PCR with primes specific to each virus. Comparison of ELSA and mRT-PCR results of 30 samples showed that numbers of infected and mixed infected samples as well as infection and mixed infection rates were significantly higher in RT-PCR (20 and 66.7%) than in ELISA (14 and 46.7%). The results confirm that mRT-PCR is more sensitive than ELISA.

• The Plant Pathology Journal
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• v.31 no.4
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• pp.388-401
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• 2015

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.