• The Plant Pathology Journal
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• v.18 no.2
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• pp.93-97
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• 2002

Aster yellows phytoplasma-infected chrysanthemums showing stunt, rosette, and excessive branching were treated with a foliar spray of 400 mg/I oxytetracycline at three-day interval for 1,2,3 and 4 months. Two months after the final treatment, new shoots from the recovered chrysanthemums showed the recurrence of the disease symptoms. However, cuttings from chrysanthemums treated with oxytetracycline did not express any photoplasma infection symptoms for more than 10 months. Also, chrysanthemums dipped in 100 mg/I oxytetracycline solution combined with a foliar spray of 400 mg/I oxytetracycline for 4 weeks showed the same results. Using an electron microscope, ultrathin sections of leaf midribs of chrysanthemum cuttings treated with oxytetracycline for 4 months did not show phytoplasma bodies 10 months after treatment. Nucleic acids from chrysanthemums, which did not express phytoplasma infection symptoms for more than 10 months, did not amplify 16S rRNA gene of phytoplasma by polymerase chain reaction. These results may have implications in the propagation of phytoplasma-free healthy stocks for a wide range of plant species.

• The Plant Pathology Journal
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• v.19 no.2
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• pp.106-110
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• 2003

Stolbur Phytoplasma was detected from Lilium Oriental hybrids showing flattened stem and flower clustering. The presence of phytoplasma was demonstrated using polymerase chain reaction（PCR) assays with phyto-plasma-universal（P1/P6）and stolbur phytoplasma-specific 16F1/R1-S primer pairs amplifying phytoplasma 16S rDNA regions. Nucleotide suquences of the phytoplasma 16S rDNA were determined. Nucleic acid extracted from lily amplified 1.5 kb DNA with a phytoplasma universal primer pair. In nested PCR, 1.1 kb PCR product was obtained using specific primer pair, indicating an isolate of stolbur phytoplasma. Nucleotide sequence of phytoplasma 16S rDNA reported in this study showed 99.5% and 99.1％ identities with two known stolbur phytoplamas (16Sr XII-A). Also, it exhibited a sequence homology of 98.0％ with phormium yellow leaf (16Sr XII-B), and 97.9％ with Australian grapevine yellows (16Sr XII-B). Meanwhile, it showed 98.1% identity with strawberry green petal phytoplama, (16Sr1-C), and 94.7 % with American aster yellows (16Sr1-B). Homology percentage of the 16S rDNA nucleotide sequence suggests that this phytoplama could be classified into the stolbur phytoplasma, subgroup A (16Sr XII-A), as a type strain stolbur.

• The Plant Pathology Journal
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• v.21 no.4
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• pp.383-386
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• 2005

In 2003 typical phytoplasma symptoms of witches' broom and flower malformation were observed on statice (Limonium sinuatum) plants grown at commercial greenhouses in Busan, South Korea. The DNA extracted from the infected leaves was amplified using universal primer pair of Pl/P6 derived from conserved 16S rRNA gene of Mollicutes giving the expected Polymerase chain reaction (PCR) product of 1.5 kb. In the nested PCR assays, the expected DNA fragment of 1.1 kb was amplified with the specific primer pair 16Fl/Rl that was designed on the basis of aster yellows (AY) phytoplasma 16S rDNA sequences. The 1.1 kb PCR products were cloned and nucleotide sequences were determined. The sequences were identical to that of Onion yellows OY phytoplasma (GenBank accession no. D12569) isolated from Onion in Japan. Electron microscopy of thin sections of leaf veins showed phytoplasma bodies in the phloem. Statice witches' broom symptom occurred on statice in commercial greenhouses in Korea was confirmed as infection of AY phytoplasma by transmission electron microscopy observation, and by determination of 16S rRNA gene sequences of phytoplasma.

• The Plant Pathology Journal
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• v.17 no.1
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• pp.57-61
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• 2001

Phytoplasmas were identified from two chrysanthemum (Dendranthema grandiflorum) plants showing different symptoms ; one with stusting, rosette, and excessive branching (Ph-ch1), and the other with stunting and chlorosis (Ph-ch2). Electron microscopy of midrib of the plants with the symptoms revealed that numerous phytoplasmas were localized in the phloem cells. The disease was transmitted from infected plants to healthy ones by grafting. Phytoplasma-specific DNA was detected in polymerase chain reaction (PCR) analysis with template DNA extracted from the leaves of Ph-ch1 and Ph-ch2, both of which yielded a same DNA band corresponding to 1.5 kb. Using a specific primer pair (R16F1/R1) synthesized based on aster yellows (AY) phytoplasma, a DNA fragment of 1.1 kb was amplified by PCR. Endonuclease restriction patterns of the 1.1 kb PCR products from Ph-ch1 and Ph-ch2, which were dgeste with each of the restriction endonucleases Sau3A, Hha, Alu and Rsa, were same as those of AY phytoplasma from periwinkle. This suggests that the chrysanthemum plants (Ph-ch1 and Ph-ch2) be infected with a phytoplasma belonging to AY phytoplasma.

• Life and Agrochemicals
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• s.283
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• pp.42-44
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• 2012

우리나라 파프리카에 발생하는 주요 바이러스는 오이모자이크바이러스(Cucumber mosaic virus, CMV), 고추모틀바이러스(Pepper mottle virus, PepMoV), 잠두위조바이러스2(Broad bean wilt virus2, BBWV2), 고추약한모틀바이러스(Pepper mild mottle virus, PMMoV), 토마토반점위조바이러스(Tomato spotted wilt virus, TSWV) 및 사탕무황화바이러스(Beet western yellows virus, BWYV) 등 6종이다. 생산량 감소 및 고품질 규격품 생산의 가장 큰 제한요인이 되고 있는 바이러스병의 피해를 최소화하기 하기 위하여 바이러스별 병징 및 발생원인에 따른 예방법을 알아본다.

• The Plant Pathology Journal
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• v.34 no.6
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• pp.532-543
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• 2018

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 Plant Pathology Journal
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• v.17 no.6
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• pp.329-335
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• 2001

Yellowing disease of palms caused by phytoplasma is spreading in the Arabian Gulf region. Surveys were conducted to determine the occurrence of the disease. Electron and fluorescence microscopy, and polymerase chain reaction (PCR) techniques were used to detect the phytoplasma associated with the yellowing disease of ornamental palm Washingtonia sp. grown in Kuwait. An accumulation of phytoplasmal DNA was observed by fluorescence microscopy in phloem tissues of diseased palms. Electron microscopy showed that phytoplasma cells were primarily confined to the phloemsieve elements of tissue samples collected from infected mature palms in the field. The pathogen was identified on the basis of molecular analysis using universal and specific nested primers in PCR amplifications. Prokaryotic 16S rDNA gene was detected in amplified PCR products. Nested PCR resulted in DNA amplification of 1.2 kbp fragment. This is the first report of a phytoplasmal rDNA gene identified from the putative causal pathogen of yellows in ornamental palms in the Arabian Gulf region.

• Korean Journal Plant Pathology
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• v.14 no.4
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• pp.294-298
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• 1998

Since 1995, boxthorn bight caused by Phytophthora spp. has occurred at Chongyang areas in Chungnam province. Infected plants showed yellows and wilt at early stage, but the symptom rapidly progressed into blight due to the decay of roots and basal stem tissues. The disease was relatively severe in poorly drained lowlands and incidence reached ca. 20% in some fields. Two species of Phytophthora were constantly isolated from freshly infected roots and asal stems. Among 39 isolates collected, 26 were identified as P. nicotianae and 13 as P. drechsleri based on their mycological characteristics. Both fungi showed strong pathogenicity to boxthorn cv. Chongyang No. 1. However, the former expressed stronger pathogenicity than the latter. Phytophthora blight of boxthorn caused by the fungi has not been reported n Korea previously.

• The Plant Pathology Journal
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• v.28 no.3
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• pp.239-247
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• 2012

Phytoplasmas have been associated with more than 46 plant species in Korea. Several vegetables, ornamentals, fruit trees and other crop species are affected by phytoplasma diseases. Six 16Sr groups of phytoplasmas have been identified and these phytoplasmas are associated with 63 phytoplasma diseases. Aster yellows phytoplasmas are the most prevalent group and has been associated with more than 25 diseases in Korea. Jujube witches' broom, paulownia witches' broom and mulberry dwarf diseases cause economic losses to host trees throughout the country. So far, Korean phytoplasmas belong to six species of 'Candidatus Phytoplasma'; 'Ca. P. asteris', 'Ca. P. pruni$^*$', 'Ca. P. ziziphi', 'Ca. P. trifolii', 'Ca. P. solani$^*$' and 'Ca. P. castaneae'. The diseases are distributed throughout the country and most of them were observed in Gyeongbuk and Chonbuk provinces. At least four insect vectors; Cyrtopeltis tenuis, Hishimonus sellatus, Macrosteles striifrons and Ophiola flavopicta have been identified for phytoplasma transmission.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.2
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• pp.89-95
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• 1991

Yellow sands often occur in Korea during April and May each year, and they are believed to come from the Mongolian Gobi desert as the snow starts to melt in Spring time. Since the analysis of aerosol particulates can hardly distinguish the origin of particulates, the isentropic analysis of meteorological data is often used for the trajectories of the long range transport of yellows sand or air pollutants. The yellow sand case of April 9 $\sim$ 15, 1988, in Korea is analyzed for the identification of long range transport of yellow sands and their trajectories in East Asia, using isentropic analyses. We have tranformed the ECMWF grid data, analyzed in pressure coordinates, into the isentropic coordinates and then have traced the 286 K and 290 K air mass which started Gobi desert. The result shows the transport of yellow sands from the Gobi desert to the Korean peninsula.