• The Plant Pathology Journal
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• 제28권3호
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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.

• The Plant Pathology Journal
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• 제39권1호
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• pp.149-157
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• 2023

Phytoplasmas were discovered in diseased Elaeocarpus sylvestris trees growing on Jeju Island that showed symptoms of yellowing and darkening in the leaves. Leaf samples from 14 symptomatic plants in Jeju-si and Seogwipo-si were collected and phytoplasma 16S rRNA was successfully amplified by nested polymerase chain reaction using universal primers. The sequence analysis detected two phytoplasmas, which showed 99.5% identity to 'Candidatus Phytoplasma asteris' and 'Ca. P. malaysianum' affiliated to 16SrI and 16SrXXXII groups, respectively. Through polymerase chain reaction-restriction fragment length polymorphism (RFLP) analyses using the AfaI (RsaI) restriction enzyme, the presence of two phytoplasmas strains as well as cases of mixed infection of these strains was detected. In a virtual RFLP analysis with 17 restriction enzymes, the 16S rRNA sequence of the 'Ca. P. asteris' strain was found to match the pattern of the 16SrI-B subgroup. In addition, the phytoplasmas in the mixed-infection cases could be distinguished using specific primer sets. In conclusion, this study confirmed mixed infection of two phytoplasmas in one E. sylvestris plant, and also the presence of two phytoplasmas (of the 16SrI and 16SrXXXII groups) in Jeju Island (Republic of Korea).

• 한국식물병리학회지
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• 제13권4호
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• pp.239-243
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• 1997

1990년 8월 충북 보은의 참깨 밭에서 전형적인 엽화병(葉化病; phyllody disease)이 발생하였다. 병징은 꽃이 잎처럼 녹색으로 변하고, 이병엽은 정상엽보다 작고 잔가지가 마치 빗자루 모양으로 총생하였고 개화 및 결실이 되지 않았다. 투과 전자현미경으로 병든 잎의 사관요소에서 phytoplasma가 존재하는 것을 확인하였다. 병든 잔가지에서 추출한 DNA를 중합효소 연쇄반응으로 분석한 결과 대추나무 빗자루병에 걸린 나무에서 증폭되는 DNA와 같은 크기의 band가 관찰되었다. 따라서 위의 시료는 phytoplasma 벙으로 확인 되었으며 참깨 엽화병으로 명명하였다. 또한 참깨 엽화병을 일으키는 phytoplasma와 대추 나무 빗자루병 phytoplasma를 PCR 증폭 및 제한효소로 절단하여 분석한 결과 이들은 서로 다른 그룹이라는 것을 알 수 있었다.

• The Plant Pathology Journal
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• 제18권3호
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• pp.109-114
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• 2002

To evaluate the phylogenetic and taxonomic status of the phytoplasmas associated with water dropwort (Oenanthe javanica DC) disease in Korea and Japan, their 16S rDNA was analyzed. DNAs extracted from water dropworts collected in Korea (Kyongnam province) and Japan (Chiba prefecture) affected by witches' broom and yellows were subjected to PCR using phytoplasma-specific primers, which amplified a 1.4-kbp fragment that included the 16S rDNA. Phytoplasmas were characterized by RFLP analysis using AluI, HaeIII, HhaI, KpnI, MseI, and RsaI restriction enzymes and by sequence analysis of the PCR products. The mater dropwort witches'broom (WDWB) and water dropwort yellows (WDY) 16S rDNA sequences were identical and closely related to onion yellows (OY, 99.9% identity), which belong to the aster yellows (AY) 16S-subgroup. However, the KpnI RFLP analyses clearly distinguished the WDY and WDWB phytoplasmas from the OY phytoplasma. The phylogenetic analysis based on 16S rDNA showed that WDWE and WDY phytoplasmas are members of a relatively homogeneous group that evolved from a common ancestor.

• The Plant Pathology Journal
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• 제28권2호
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• pp.191-196
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• 2012

Periwinkle seedlings (Cantharanthus roseus) were inoculated with jujube witches'- broom (JWB) phytoplasma via grafting to analyze the migration of JWB phytoplasmas within the host plant. The phytoplasmas were detected using nested polymerase chain reaction (PCR) and fluorescence microscopy. Fluorescence microscopy was a simple and easy method of detecting phytoplasmas; however, it was not sufficiently sensitive to detect very low phytoplasma concentrations. Therefore, the migration of JWB phytoplasma was investigated through PCR. The first migration of JWB phytoplasma from an infected tissue to healthy tissues occurred late. After grafting, the phytoplasmas moved from the inoculated twig (or scion) to the main stem, which took 28 days. Afterward, the phytoplasma migrated faster and took less than 4 days to spread into the roots from the main stem. All twigs were then successively colonized by the JWB phytoplasmas from the bottom to the top. JWB phytoplasma was detected via nested PCR in all parts of the periwinkle seedling 82 days after inoculation. Based on these results, the inoculated JWB phytoplasma appeared to migrate downward to the roots along the main stem during the early stages, and then continued to move upward, colonizing twigs along the way until they reached the apex.

• The Plant Pathology Journal
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• 제17권4호
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• pp.189-193
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• 2001

The relationships between the phytoplasmas infecting Zizyphus jujuba and Paulownia coreana were investigated by PCR-RELP. The 16S rRNA genes of the phytoplasmas were analyzed and compared with each other after PCR amplification. The amplified bands 1.4 kb in size were analyzed by both restriction digestion and sequencing after cloning into a plasmid vector. In some cases, two different kinds of inserts were observed in the isolates that originated from a single plant. However, many of them appeared to be the amplification products of chloroplastic 16S rRNA gene of host plants. The phytoplasma gene could be differentiated from the chloroplastic gene by restriction digestion of the plasmids carrying the amplification products. Only the recombinant plasmids carrying phytoplasma 16S rRNA gene produced a 1.4 kb band when digested with the enzyme BanII. Of the 52 recombinant plasmids analyzed, 42 appeared to contain inserts that originated from the chloroplastic 16S rRNA gene of the host plants. No variation was detected among 16S rRNA gene of nine phytoplasma isolates infecting Z. jujuba. However, the phytoplasmas infecting Z. jujuba were different from that infecting P. coreana.

• The Plant Pathology Journal
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• 제17권5호
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• pp.295-299
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• 2001

The relative density of phytoplasmas in witches'broom (WB)-infected jujube trees was investigated using compatitive polymerase chain reaction (PCR). During dormant and defoliating seasons, the densities of phytoplasmas were about the same in roots and twigs. In early growing season, the density showed the highest rates in roots, then in twigs and in petioles. however, the density was highest in petioles and the lowest in roots during actively growing season. Throughout the year, root samples did not show any serious fluctuation compared with that of t2wigs and petioles. Density was lowest during actively growing season in root samples. In contrast, petiole sample densities varied to a great extent depending on the season, very high during actively growing season, but very low during the early growing season, In twig samples, the densities were very high and almost the same in both defoliating and dormant seasons. Among the parts of the trees, phytoplsma density was the most stable in root samples throughout the year. The highest densities of phytoplasmas were about the same in all tree parts. These results suggest that the phytoplasmas may overwinter not only in roots but also in twigs, and that multiplication rate of phytoplsma becomes very high right after the early growing season.

• The Plant Pathology Journal
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• 제27권4호
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• pp.367-371
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• 2011

Multiplex PCR assays were developed for the simultaneous detection of ten important Korean quarantine phytoplasmas. The species-specific primers were designed based on ribosomal protein, putative preprotein translocase Y, immunodominant protein, elongation factor TU, chaperonin protein and the 16S rRNA genes of 'Candidatus (Ca.) Phytoplasma' species. Three main primer sets were prepared from ten designed primer pairs to limit nonspecific amplification as much as possible. The multiplex PCR assay using the three primer sets successfully amplified the correct conserved genes for each 'Ca. Phytoplasma' species. In addition, ten important 'Ca. Phytoplasma' species could be easily determined by recognizing band patterns specific for each phytoplasma species from three primer sets. Moreover, a high sensitivity of multiplex PCR for each primer set was observed for samples containing a low DNA concentration (10 ng/${\mu}l$). This study provides the useful multiplex PCR assay as a convenient method to detect the presence of ten important quarantine phytoplasmas in Korea.

• The Plant Pathology Journal
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• 제17권1호
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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.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 1999년도 임시총회 및 추계 학술발표회
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• pp.9-9
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• 1999