• Korean journal of applied entomology
• /
• v.5_6
• /
• pp.1-7
• /
• 1968

The present investigation was initiated to find out the possible insect vector of the paulownia witches'-broom virus disease. 1. Among a number of piercing-sucking mouth type insects that were feeding on the witches'-broom infected Paulownia leaves, the tobacco leaf bug, Cyrtopeltis tenuis REUTER, was most abundant. Eggs, nymphs and adults of Cyrtopeltis tenuis were observed from the mid-August through the end of October. 2. It was found that Paulownia witches'-broom virus is transmitted by Cyrotopeltis tenuis. 3. On young Pnulownia plants, first symptom appeared twenty days after exposure to virus-bearing colonies of Cyrtopeltis tenuis. Forty days after exposure to these viruliferous insects, the characteristic symptom of Paulownia witches'-broom was apparent. 4. Paulownia witches' -broom virus was also transmitted by Cyrtopeltis tenuis to calendula and morning glory. No app"rent symptom was observed from tomato, carrot. aster, zinnia, cosmos, soybean and plantago at least until sixty days after exposure to the viruliferous colonies of Cyrtopeltis tenuis. 5. Calendula and morning glory appear to be highly suitable test plants for Paulownia witches'-broom vims because of their relatively short incubation period and distinct symptom appearance.

• The Plant Pathology Journal
• /
• v.18 no.3
• /
• pp.109-114
• /
• 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.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.8
• /
• pp.1047-1054
• /
• 2013

Witches' broom of lime is a disease caused by Candidatus Phytoplasma aurantifolia, which represents the most significant global threat to the production of lime trees (Citrus aurantifolia). Conventional disease management strategies have shown little success, and new approaches based on genetic engineering need to be considered. The expression of recombinant antibodies and fragments thereof in plant cells is a powerful approach that can be used to suppress plant pathogens. We have developed a single-chain variable fragment antibody (scFvIMP6) against the immunodominant membrane protein (IMP) of witches' broom phytoplasma and expressed it in different plant cell compartments. We isolated scFvIMP6 from a naïve scFv phage display library and expressed it in bacteria to demonstrate its binding activity against both recombinant IMP and intact phytoplasma cells. The expression of scFvIMP6 in plants was evaluated by transferring the scFvIMP6 cDNA to plant expression vectors featuring constitutive or phloem specific promoters in cassettes with or without secretion signals, therefore causing the protein to accumulate either in the cytosol or apoplast. All constructs were transiently expressed in Nicotiana benthamiana by agroinfiltration, and antibodies of the anticipated size were detected by immunoblotting. Plant-derived scFvIMP6 was purified by affinity chromatography, and specific binding to recombinant IMP was demonstrated by enzyme-linked immunosorbent assay. Our results indicate that scFvIMP6 binds with high activity and can be used for the detection of Ca. Phytoplasma aurantifolia and is also a suitable candidate for stable expression in lime trees to suppress witches' broom of lime.

• Korean journal of applied entomology
• /
• v.15 no.3 s.28
• /
• pp.107-110
• /
• 1976

A Witches'-broom disease of jujube (Zizyphus jujuba) with which mycoplasma-like bodies are associated is wide spread in South Korea. Jujube trees with witches'-broom symptoms were selected from 15-20 year old planting and treated with solution of oxytetracycline hydrochloride (Terramycin). Treatments were 1) one injection on April; 2) one postharvest injection on October; 3) two injections (April and July); 4) three injections (April, June and August) and 5) an untreated control. Each injection consisted of 500ml of 1,000 p.p.m. solution of oxytetracycline HCl transfused into affected trees from plastic reservoir through plastic tubes connected to 3 small holes drilled in the basal part of the tree trunks. Complete remission of witches'-broom symptoms was accomplished within one growing season by one spring (April) injection. One postharvest (Oct.) injection also prevented the symptoms in the following growing season. Two and three injection treatments prevented the symptoms for at least two growing seasons and restored previously severely diseased trees to normal or near normal conditions. Remission of symptoms was found only above the injection site while current season witches'-brooms developed from areas below the injection site and from untreated main scaffolds. The results of this experiment demonstrates that transfusion treatment with oxytetracyclin HCl is feasible for the practical control of witches'-broom of jujube.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2003.10a
• /
• pp.73.2-73
• /
• 2003

Typical whiches broom symptoms caused by phytoplasma were observed in Ash (Fraxinus rhynchophylla Hence) in Korea. The symptoms were showing abnormally small leaves, short internodes, and proliferation of shoots. Fluorescence and electron microscopy of leaf midribs revealed phytoplasma positive DAPI fluorescence and numerous phytoplasma bodies localized in the phloem sieve tubes. Phytoplasma DNA of 1.8 Kb was detected consistently from all symptomatic samples by the amplification of phytoplasma DNA with the phytoplasma specific primer pair Pl/P7. But no phytoplasma DNA was detected in healthy ash seedlings. Based on sequence analyses of an amplified region, this phytoplasma is closely related to Eqilodium phyllody, Mulberry dwarf, and Aster yellows phytoplasmas with the homology of 99.95 ％, 99.79 ％ and 99.78 ％, respectively, This phylogenetic analyses indicate that ash witches broom phytoplasma but is evidently distinct from the ash yellows group 16SrⅦ and should be classified into the Aster yellows group 16SrⅥ.

• Journal of agriculture & life science
• /
• v.43 no.3
• /
• pp.1-6
• /
• 2009

This study has been carried out to measure the extent of damage for Witches' broom of cherry trees planted as street trees along the 5.16 road around the Halla Mountain. This study is expected to provide effective measures to prevent the infection of witches' broom. Among the cherry trees examined, almost all the trees of 40 years or over were severely infected. Those around 30 years old were infected as well, though they showing medium level of disease symptoms. However, cherry trees of less than 23 years were observed to be healthy without showing any symptoms. Cherry trees spontaneously growing within 30m width of the 5.16 road in the section from Sanchondan to Kyunwolak were less severely infected by Witches' broom (Taphrima waesneri), though there was a difference by tree age.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.1
• /
• pp.81-88
• /
• 2011

The anti-phytoplasma activities of surfactin (derived from Iranian native Bacillus subtilis isolates) and tetracycline towards Candidatus "Phytoplasma aurantifolia", the agent of lime Witches' broom disease, were investigated. HPLC was used to quantify the surfactin production in four previously characterized native surfactin-producing strains, and the one producing the highest amount of surfactin (about 1,500 mg/l) was selected and cultivated following optimized production and extraction protocols. Different combinations of purified surfactin and commercial tetracycline were injected into artificially phytoplasmainfected Mexican lime seedlings using a syringe injection system. An absolute quantitative real-time PCR system was developed to monitor the phytoplasma population shifts in the lime phloem during 3 months following the injections. The results revealed that the injections of surfactin or tetracycline had a significant inhibitory effect on Candidatus "P. aurantifolia". However, the combined treatment with both surfactin and tetracycline (1:1) resulted in the highest inhibition due to a synergic effect, which suppressed the phytoplasma population from about $2{\times}10^5$ to less than 10 phytoplasma units/g plant tissue.

• Korean journal of applied entomology
• /
• v.4
• /
• pp.7-10
• /
• 1965

In an experiment to evaluate the various aspects of symptom of witches' broom of jujube tree with two different kinds of scions, taken from diseased plant and stem- grafted upon sound stocks-one cut before wintering(stored in cellar), the other after wintering, it was observed that the disease rate of those cut before wintering(Nov.) was $\98\%$ whereas those cut after wintering(March) showed much lower rate, $3\%$ initially and gradually increased up to $39\%$. In another experiment of diseased bud grafted into healthy seedling, the finding made in the following year was that 14 stocks(only one of which salt union by callusing) were infected out of the given 23- in the initial stage only 4, yet gradually increased to the number of 14. The shoots from the ground portion of the diseased stock were in general more quickly subjected to the disease than the others. Under natural condition, the diseased trees develop at first seemingly the same leaves as healthy ones; it is not until the branches and loaves grow to a considerable degree that the symptom appears. Once appearing, tile disease grows and the symptom continues to appear as late as in Sept. and early Oct., causing tile plant to develop the extraordinary branches and leaves of extremely reduced size, the typical symptom of witches' broom. Such phenomenon can be observed in the experiments of the foregoing paragraphs. And the suckers and roots of diseased plant are bound to be infected, it was found out with no exception. Viewing from the results of the above experiments and observation, it is believed that the low temperature during winter causes the virus in the above-ground portion of diseased plant to diminish or inactivated, and subsequently the virus in the roots moves up or multiply in the sprouting season.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2000.10a
• /
• pp.49.2-49
• /
• 2000

• Research in Plant Disease
• /
• v.26 no.1
• /
• pp.19-28
• /
• 2020

Jujube witches' broom (JWB) disease is a high-risk plant disease that occurred on and devastated jujube orchards throughout South Korea in the 1950s. Recently, as the jujube cultivation area has been significantly increased nationwide, we investigated the disease in jujube orchards in the Boeun region to obtain basic information for proactively evaluating the risk of JWB outbreaks from 2017 to 2019. A field trial was conducted to evaluate the effect of the trunk injection of Sungbocycline (a. i. oxytetracycline calcium alkyl trimethyl ammonium 17%, OTC). The incidence of JWB disease was very low in Boeun, but it was gradually increased mainly in the area and on the farms where it had occurred previously. The trunk injection with OTC was most effective in the early stages of growth. However, even though the trees were treated with OTC, disease symptoms appeared in other healthy branches in severely affected trees. When the tree was first injected with OTC in June, the control efficacy of second injection was higher one month after the first injection than five months. These results suggest that early diagnosis based on various symptoms and early control based on them can be very effective in preventing JWB disease in advance and increasing control efficacy.