• The Plant Pathology Journal
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• 제26권4호
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• pp.394-401
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• 2010

Resin flow, symptom development, and lignin biosynthesis in response to wounding and fungal inoculation were investigated in Pinus rigida and Pinus densiflora. The two-year-old seedling stems were subjected to three types of treatments: (i) wounding without inoculation, (ii) wound-inoculation with a conidial suspension of Fusarium circinatum, and (iii) pre-wounding woundinoculation with the fungus 20 days after the initial wounding. Resin flow from wounding sites was more evident in P. rigida than P. densiflora in all treatments. The wound-inoculation with the fungus induced almost two-fold higher levels of resin flow than the other treatments in both species. The pre-wounding woundinoculation appeared to result in a decrease in pitch canker development in the two pine species. Some reductions in disease severity were observed in the prewounding wound-inoculated P. rigida, showing a mean disease severity of less than 85%, compared with approximately 100% in the wound-inoculated stems. Disease severity was approximately 50% in the woundinoculated P. densiflora, whereas 10% in the pre-wounding wound-inoculated stems. Higher amounts of lignin were found from bark (ca. 40%) than from xylem (ca. 30%). The wound-inoculated bark and the pre-wounding wound-inoculated bark exhibited higher amounts of lignin among the other treatments. These results suggest that the wound-inoculation apparently prompt the increase in resin flow and lignin biosynthesis from the two pine species, and the prior wounding may be involved in decreased disease severity against the further invasion of F. circinatum.

• Mycobiology
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• 제34권2호
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• pp.61-66
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• 2006

Chestnut blight disease caused by Cryphonectria parasitica is widely distributed throughout chestnut tree plantations in Korea. We surveyed 65 sites located at 9 provinces in South Korea, and isolated 248 virulent and 3 hypovirulent strains of chestnut blight fungus. Hypovirulent strains had dsRNA virus in the cytoplasm, which is one of the typical characteristics of hypovirulent strains. In addition, they showed more characteristics of hypovirulent strains, i.e., suppressed conidiation, reduced pigmentation in colony color, and reduced phenol oxidase activity as well as reduced pathogenicity. Hypovirulent strains, KCPH-22, KCPH-135 and KCPH-136, had a genomic dsRNA band with the molecular weight of 12.7 kb, which is the L-dsRNA of CHV1. They also had a 2.7 kb defective dsRNA band. Single conidia isolated from hypovirulent strains were cultured and various phenotypes and absence of dsRNA bands were obtained from single conidial cultures, which means that hypovirulence transmission is unstable in asexual reproduction and variations in viral heredity by asexual reproduction. Biocontrol trial using hypovirulent strains was also carried out in the chestnut tree plantations, and canker expansion in the treated trees was stopped and healed by callus formation at the margin of the canker. These results show the potentials in successful biocontrol of chestnut blight if the vegetatively compatible hypovirulent strains could be directly used around the canker formed by compatible virulent strains.

• 식물병연구
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• 제24권3호
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• pp.175-181
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• 2018

2013년과 2014년 자연감염된 과수원에서 재배되는 국산 골드키위 품종인 해금에서 발생하는 궤양병, 세균성점무늬병과 과실무름병의 발병률을 그린키위 품종인 헤이워드와 비교하였다. 2013년과 2014년 P. syringae pv. actinidiae biovar 2 (Psa2)에 자연감염된 키위 과수원에서 함께 재배되고 있는 헤이워드 품종에서궤양병발병률은각각18.5%와17.3%인반면에해금 품종에서 궤양병 발병률은 1.2%와 0%였다. 2013년과 2014년 A. valerianellae에 의한 세균성점무늬병 발병률은 63.5%와 16.2%였으나 해금 품종에서는 전혀 발병되지 않았다. 2013년 관행방식에 의해 함께 재배되고 있는 과수원에서 헤이워드와 해금 품종에서 과실무름병 평균 발병률은 각각 24.2%와 6.3%였으며 2014년에는 각각 20.5%와 4.4%였다. 두 품종 모두에서 과실무름병을 일으키는 가장 중요한 병원균은 B. dothidea로 확인되었다.

• 식물병연구
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• 제10권4호
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• pp.310-312
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• 2004

Pseudomonas syringae pv. actinidiae는 참다래 궤양병을 일으키는 세균이다. 식물독소인 coronatine 생합성에 관여하는 유전자 중 하나인 cfl의 염기서열로부터 설계된 primer를 사용한 nested PCR 방법을 토양시료에 적용시켰다. 이 primer 세트와 우리나라에서 분리된 P. syringae pv. actinidiae가 접종된 토양으로부터 얻은 DNA로 두 번의 PCR을 행했을 때 665 bp와 310 bp의 절편이 각각 증폭되었다. 이 시스템을 참다래 궤양병으로 폐원된 과수원의 토양조사에 적용시킨 결과 여섯 곳으로부터 채취한 토양시료 모두에서 특이적인 310 bp의 PCR 산물이 증폭되었다.

• The Plant Pathology Journal
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• 제33권6호
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• pp.554-560
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• 2017

After 20 years of steady increase, kiwifruit industry faced a severe arrest due to the pandemic spread of the bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa). The bacterium penetrates the host plant primarily via natural openings or wounds, and its spread is mainly mediated by atmospheric events and cultural activities. Since the role of sucking insects as vectors of bacterial pathogens is widely documented, we investigated the ability of Metcalfa pruinosa Say (1830), one of the most common kiwifruit pests, to transmit Psa to healthy plants in laboratory conditions. Psa could be isolated both from insects feeding over experimentally inoculated plants, and from insects captured in Psa-infected orchards. Furthermore, insects were able to transmit Psa from experimentally inoculated plants to healthy ones. In conclusion, the control of M. pruinosa is recommended in the framework of protection strategies against Psa.

• Journal of Microbiology and Biotechnology
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• 제13권1호
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• pp.110-118
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• 2003

Pseudomonas syringae pv. actinidiae strains, which cause canker disease in kiwifruit, were collected from kiwifruit orchards in Korea and identified using biochemical and physiological tests. The nucleotide sequences of the 16s rDNA and 16s-23s internally transcribed spacer of the isolates were found to be Identical to those of' the pathotype strain, Kwl 1, of P syringae pv. actinidiae. Remarkably, no coding sequence for phaseolotoxin biosynthesis or phaseolotoxin- resistant ornithine carbamoyltransferase was found by PCR amplification in any of the new Korean isolates of pseudomonas syringae pv. actinidiae, although this was clearly identified in the control pathotype Kwl 1 reference strain. In contrast, three primer sets derived from the coronatine biosynthetic gene cluster and DNA from the Korean strains yielded amplified DNA fragments of the expected size. A sequence analysis of the PCR products revealed that P. syringae pv. actinidiae and the Korean strains of pv. actinidiae contain coronafncate ligase genes (cfl)with identical sequences, whereas their. corR genes exhibited 91% sequence similarity. The production of coronatine, instead of phaseolotoxin, by the Korean strains of P. syringae pv. actinidiae was confirmed by a bioassay using reference pathovars known to produce coronatine and phaseolotoxin. The genes for coronatine biosynthesis in the Korean strains of P. syringae pv. actinidiae were found to be present on plasmids.

• 한국산림과학회지
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• 제6권1호
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• pp.6-10
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• 1967

In the present paper author investigated the symptom, pathogenic fungus and pathogenicity of Endothia canker of Carpinus laxiflora in Korea, and made clear the indistinct discription on its pathogen in the past. 1. The pathogen is identified as Endothia fluens (Schw.) Shear et Stevens. The discription is recorded as follows: Stromata cortical, erumpent, spherical or conical, outer yellowish-brown and inner yellowish, 0.5 to 2.5 mm in diameter; perithecia irregularly embeded in the bottom of stroma, 7 to 23 in a stroma usually spherical to elliptical or irregular, 235 to $370{\mu}$ in diameter, with black slender necks; each neck open the papilliate ostiole to the surface, about 250 to $400{\mu}$ in length; asci clavate or fusoid, colorless, 31.16 to 42.64 by 6.54 to $8.20{\mu}$ in size, average 37.02 by $6.84{\mu}$, with 8 ascospores in double line; ascospores elliptical, ovate or cylindrical, with rounded ends, hyaline, 1-septate, not constrict at the septum, 6.51 to 9.30 by 3.16 to $3.72{\mu}$, average 7.61 by $3.44{\mu}$ in size; pycnidia formed abundantly in stroma. spherical at first but later irregular large cavity by fussing each other; pycnospores oblong or rod-shaped, hyaline, non-septate, 3.8 by $1.9{\mu}$ in size; spore-horn formed abundantly under moist condition. 2. The pathogen is wound parasite invading the hosts through the wound. But after the infection is established, expanding the disease lesion is swiftly vigorus.

• Mycobiology
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• 제47권3호
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• pp.319-328
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• 2019

Cytospora is a genus including important phytopathogens causing severe dieback and canker diseases distributed worldwide with a wide host range. However, identification of Cytospora species is difficult since the currently available DNA sequence data are insufficient. Aside the limited availability of ex-type sequence data, most of the genetic work is only based on the ITS region DNA marker which lacks the resolution to delineate to the species level in Cytospora. In this study, three fresh strains were isolated from the symptomatic branches of Elaeagnus angustifolia in Xinjiang Uygur Autonomous Region, China. Morphological observation and multi-locus phylogenetic analyses (ITS, LSU, ACT and RPB2) support these specimens are best accommodated as a distinct novel species of Cytospora. Cytospora elaeagnicola sp. nov. is introduced, having discoid, nearly flat, pycnidial conidiomata with hyaline, allantoid conidia, and differs from its relatives genetically and by host association.

• The Plant Pathology Journal
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• 제37권2호
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• pp.124-136
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• 2021

Bark canker, wood discoloration, and wilting of the duku tree (Lansium domesticum) along the watershed of Komering River, South Sumatra Province, Indonesia first appeared in 2013. The incidence of tree mortality was 100% within 3 years in badly infected orchards. A Ceratocystis species was consistently isolated from the diseased tissue and identified by morphological and sequence analyses of the internal transcribed spacer (ITS) and β-tubulin regions. Pathogenicity tests were conducted and Koch's postulates were confirmed. The fungus was also pathogenic on Acacia mangium, but was less pathogenic on mango. Partial flooding was unfavourable for disease development. Two described isolates (WRC and WBC) had minor variation in morphology and DNA sequences, but the former exhibited a more pathogenic on both duku and acacia. The ITS phylogenies grouped the most pathogenic isolate (WRC) causing wilting of the duku tree within the aggressive and widely distributed ITS5 haplotype of C. fimbriata.

• 식물병연구
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• 제24권2호
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• pp.123-131
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• 2018

전세계뿐만 아니라 국내에서도 참다래의 품질을 높이기 위한 신품종 육성이 꾸준히 이루어지고 있다. 새롭게 육성된 품종은 과실 특성뿐만 아니라 병해충 발생 양상에 대한 자료가 전무하기 때문에 연속된 조사를 통해 기존 재배 품종인 '헤이워드'와 비교한 기초 자료가 제시되어야 한다. 따라서 참다래의 주요 병해충으로 알려진 점무늬병과 궤양병 그리고 노린재류에 대한 발생 조사를 3년간 실시하였다. 지역과 재배 환경에 따르면 기온이 높을수록 점무늬병이, 강수량이 많을수록 궤양병의 발생빈도가 높았고, 노지 재배보다는 비가림 재배에서 병 발생을 낮출 수 있는 것으로 보였다. 또한, 신품종 간에 '감록'은 노지 재배 환경에서 다른 품종들에 비해 병에 매우 감수성인 것으로 보였으나, 비가림 재배 환경에서 이를 극복할 수 있는 것으로 보였다. 노린재류 발생 조사에서는 페로몬 트랩을 포장 내부에 설치했을 때 과실 피해가 증가하는 것으로 보여 농가 외부에 트랩을 설치하는 것이 바람직할 것으로 보인다.