• The Plant Pathology Journal
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• 제36권1호
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• pp.106-110
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• 2020

Citrus mosaic sadwavirus (CiMV) is a closely related virus with the Satsuma dwarf virus (SDV) along with Navel orange infectious mottling virus (NIMV), Natsudaidai dwarf virus (NDV), and Hyugagatsu virus (HV). The present study found that the typical symptoms of CiMV-infected citrus fruits include the appearance of dark blue speckles or ringspots on fruit rinds and the browning of oil glands in the spots as rind coloring began. As rind coloring progressed, the spots gradually faded, whereas the browning of the oil glands worsened to the point that the tissues surrounding the oil glands became necrotic. In very early satsuma mandarins (Citrus unshiu 'Miyamoto Wase') and 'Setoka' cultivar (C. hybrid 'Setoka') of late-maturity citrus, the symptomatic fruits were eventually dropped. And in early satsuma mandarin (C. unshiu 'Miyakawa Wase'), the peel hardness of the virus-infected fruit (1,618.3 ± 305.5, g-force) was more than twice as hard as that of the healthy fruit (636.5 ± 39.1, g-force). The ratio of flesh weight to total fruit weight was higher for the healthy fruit (77.3 ± 1.7%) than for the infected fruit (70.7 ± 0.6) and peel puffing was more severe in the infected fruit (2.9 ± 0.4 mm) than in the healthy fruit (0.9 ± 0.2 mm). The soluble solids content in infected citrus fruits was less values than the healthy fruit by 0.5-1.5 °Brix. These findings reveal that CiMV infection on citrus trees reduces the fruit quality of citrus.

• 한국균학회지
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• 제48권3호
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• pp.329-335
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• 2020

2008년부터 2017년도에 제주, 홍천 등에서 산철쭉에서 모무늬 증상을 나타내는 잎을 채집하였다. 산철쭉모무늬 증상은 빈번하게 잎에만 발생하여 식물의 관상가치를 떨어트리고 조기낙엽을 유발하였다. 변색부는 잎의 윗면에 작고 담갈색 내지 흑자색 점무늬가 먼저 나타나며, 잎의 세맥으로 경계가 구분되어 모무늬 또는 부정형의 증상을 나타냈다. 산철쭉에서 분리한 균주를 동정하고자 형태적 특징과 actin (Act), translation elongation factor 1-alpha (EF), internal transcribed spacer (ITS), 28S nrDNA (LSU), RNA polymerase II second largest subunit (RPB2) 염기서열을 분석하였다. 형태적 특징을 재확인한 염기서열 분석결과 Sp. azaleae와 99~100%의 상동성을 나타냈으며, 계통수를 작성하였을 때도 Sp. azaleae 계통군에 속하였다. 따라서 산철쭉에 모무늬 증상에 관여하는 곰팡이는 Sp. azaleae로 동정되었다.

• 식물병연구
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• 제24권4호
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• pp.292-301
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• 2018

Alternaria leaf spot disease has been a concern during a tomato production in greenhouse. In vitro antifungal activities of vapours of four plant essential oils, cinnamon oil, fennel oil, origanum oil and thyme oil, were investigated during in vitro conidial germination and mycelial growth of Alternaria alternata causing the tomato leaf spots to find eco-friendly alternatives for chemical fungicides. The four plant essential oils showed different antifungal activities against in vitro conidial germination of A. alternata in dose-dependent manners, and cinnamon oil vapour was most effective to suppress the conidial germination. The four plant essential oils showed similar antifungal activities against the in vitro mycelial growth of A. alternata in dose-dependent manners, but low doses of thyme oil vapour slightly increased in vitro mycelial growth of A. alternata. Necrotic lesions on the A. alternata-inoculated tomato leaves were reduced differently depending on kinds and concentrations of plant essential oils. Delayed conidial germination and germ-tube elongation of A. alternata were found on the tomato leaves treated with cinnamon oil and origanum oil vapours at 6 hpi. These results suggest that volatiles from cinnamon oil and origanum oil can be provided as alternatives to manage Alternaria leaf spot during the tomato production eco-friendly.

• Mycobiology
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• 제46권2호
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• pp.172-176
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• 2018

A new species belonging to the genus Alternaria was isolated from the necrotic leaf spots of Brassica rapa subsp. pekinensis in Yuseong district, Daejeon, Korea. It is an occasional isolate, not an etiological agent, which is morphologically similar to A. broccoli-italicae, but differs in conidial size and conidiophore shape. Phylogenetic analysis using the sequence datasets of the internal transcribed spacer (ITS) region of the rDNA, glyceraldehyde-3-phosphate dehydrogenase (gpd), and plasma membrane ATPase genes showed that it is distantly related to A. broccoli-italicae and closely related to Alternaria species in the section Pseudoalternaria, which belonged to a clade basal to the section Infectoriae. Morphologically, the species is unique because it produces solitary conidia or conidial chains (two units), unlike the four members in the section Pseudoalternaria that produce conidia as short branched chains. It exhibits weak pathogenicity in the host plant. This report includes the description and illustration of A. brassicifolii as a new species.

• 한국환경과학회지
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• 제12권6호
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• pp.659-664
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• 2003

The experiment was carried out to investigate the effects of sulfuric acid and nitric acid among the main components of simulated acid rain (SAR) on the growth of vegetative organs and seed germination of Arabidopsis thaliana. The Arabidopsis treated with SAR supplemented with sulfuric and nitric acids, respectively, showed 28% and 30% decrease of shoot and root growth compared to the control plants, and also many necrotic spots on leaf surfaces after SAR treatment were observed. The shoot and root length for plants grown with nitric acid rain was 14% and 17% lower, respectively, compared to the control, whereas those grown with sulfuric acid rain was 24% and 25% lower than control plants. When Arabidopsis seeds were sown in distilled water, germination rate was 100% after 7 days. However, 80% in SAR medium supplemented with sulfuric and nitric acids, 88% in sulfuric acid rain medium and 93% in nitric acid rain medium. The germination abilities of seeds harvested from SAR supplemented with sulfuric and nitric acids, sulfuric acid rain, and nitric acid rain were 73%, 73% and 94%, respectively. Consequently, sulfuric acids showed more inhibitory effects than nitric acids on the growth of vegetative organs as well as germination rates in Arabidopsis.

• The Plant Pathology Journal
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• 제20권4호
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• pp.297-301
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• 2004

A Tomato spotted wilt virus (TSWV-KP) was isolated from Paprika (Capsicum annuum var. grossum) showing necrosis spot on the leaves and malformation of the fruit in Yesan, Korea. The virus infected Chenopodium amaranticolor, C. quinoa, Petunia hybrida, Nicotiana glutunosa, Gomphrena globosa, and Physalis floridana. Ten plants including tomato were observed to have systemic TWSV-KP infection. The virus produced necrosis or necrotic ring spots on the inoculated leaves and mosaic, vein necrosis or death on the upper leaves of Datura stramonium, N. clevarandii, N. rustica, and N.tabacum cvs. Thin sections of the infected leaf tissue contained spherical to oval particles, a characteristic of a Tospovirus. The virion contained three molecules of genomic RNAs, which were approximately 9.0, 4.9 and 3.0 kb. The nucleocapsid (N) protein of the purified virion migrated as a single band with molecular weight of about 29 kDa in SDS-PAGE. The N gene of TSWV-KP showed 96.5-97.2% and 97.7-98.5% identities to the three different TSWV isolates of Genbank Database at the nucleotide and amino acid, respectively.

• The Plant Pathology Journal
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• 제17권3호
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• pp.128-140
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• 2001

Infection of pepper leaves by Colletotrichum cocodes at the two- and eight-leaf stages caused susceptible and resistant lesions 96 h after inoculation, respectively. At the two-leaf stage, progressive symptom development occurred on the infected leaves. In contrast, localized necrotic spots were characteristic symptoms at the eight-leaf stage. Infected leaves at the two-leaf stage exhibited cell death accompanied by the accumulation of autofluorescent compounds. At the eight-leaf stage, pepper leaves infected by the anthracnose fungus displayed localized autofluorescence from the symptoms. Infection of pepper leaves by C. cocodes at the two-leaf stage resulted in its rapidand massive colonization of all the leaf tissues including the vascular tissue, together with cytoplasmic collapse, distortion of chloroplasts, and disruption of host cell walls. However, penetration of C. cocodes was very limited in the older leaf tissues of pepper plants at the eight-leaf stage. Fungal hyphae grew only in the intramural spaces of the epidermal cell walls at this stage. Occlusion of amorphous material in xylem vessels, aggregation of fibrillar material in inter-cellular spaces, and deposition of protein bodies were found as resistance responses to C. cocodes.

• The Plant Pathology Journal
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• 제28권4호
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• pp.390-400
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• 2012

Eight potato-producing provinces of Iran were surveyed during the growing seasons of 2004-2006 to detect the presence of Tomato yellow fruit ring virus (TYFRV), a tentative species in the genus Tospovirus. A total of 1,957 potato leaf samples were collected from plants with tospovirus-like symptoms of chlorotic or necrotic spots, chlorosis and necrosis. The samples were tested by enzyme-linked immunosorbent assay using TYFRV-specific antibodies. Among those tested, 498 samples (25.4%) were found to be infected with the virus. The virus was detected in 72.4% of the potato fields in all provinces surveyed. Thirteen potato isolates of TYFRV were selected for further biological and molecular studies. Based on their reactions on Nicotiana tabacum plants, the isolates were separated into two groups, namely L (local infection) and N (systemic infection). The nucleotide sequences of the nucleoprotein (N) genes of the isolates were determined and compared with the homologous sequences in Genbank. No recombination evidence was found in the isolates using different recombination-detecting programs. In the phylogenetic tree, the potato isolates fell into two major groups: IRN-1 and IRN-2 corresponding to the two biologically separated groups. This study shows for the first time the biological and phylogenetic relationships of geographically distant TYFRV isolates from potatoes in the mid-Eurasian country of Iran.

• 한국식물병리학회지
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• 제14권5호
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• pp.433-439
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• 1998

The studies on the ecology of virus disease on Chinese cabbage (Brassica campestris subsp. pekinensis) cultivated in alpine area of Kangwon province during summer season to analyse its influence on damage and develope a prediction model were performed from 1993 to 1997. Virus disease on Chinese cabbage occurring in the alpine area showed various symptom types and among there, necrotic spots and dwarf were mainly detected. The disease was increased from early August and continued mid September in every year. The occurrence of virus disease was the highest in 1994 with 20.5%, and the number of aphid vectors were also the highest during the same period. The number of aphids in the alpine areas showed twice peaks every year. For the analysis of damage by virus infection, the infection and injured ratio of all treatments were more than 90% and 80%, respectively. The most important factor for the occurrence of virus disease on Chinese cabbage was temperature. Factors influencing the development of the viral disease in the alpine area were maximum temperature and number of aphid vectors.

• The Plant Pathology Journal
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• 제20권2호
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• pp.131-134
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• 2004

A strain of Cucumber mosaic virus (CMV) was isolated from a weed, water chickweed (Stellaria aquatica), growing in the pepper field in Chunchon, Korea. This isolate, CMV-Sa, was differentiated from other CMVs based on biological properties and nucleotide sequence analysis of the coat protein (CP) gene. CMV-Sa showed different reactions to all the tested plants, except Capsicum annuum and Cucumis sativus, when compar-ed with those of CMV-Mf (subgroup I) and CMV-PaFM (subgroup II). Remarkably, in Nicotiana tabacum cvs. Samsun, Xanthi-nc and Ky-57, CMV-Sa induced local necrotic ring spots on the inoculated leaves and venal wave pattern and mosaic on the upper leaves. RNA analysis, serology, and RT-PCR of CP gene showed that CMV-Sa belonged to subgroup I of CMV. However, restriction enzyme analysis of the cDNA using AluI, HhaI, HincII, HindIII, HinfI and MspI showed that CMV-Sa was distinct from that of CMV-Mf. Based on comparison of the nucleotide of CP gene and deduced amino acid sequences between other CMV strains, CMV-Sa was closely related to CMV-Mf with 93.7% and 97.2 % identity, respectively.