• 식물병연구
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• 제24권3호
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• pp.182-192
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• 2018

화상병은 우리나라에서 그동안 존재하지 않았던 금지병으로서 2015년 최초로 발병한 후 아직 박멸되지 않아, 국내 확산 연구가 필요하다. 병 삼각형 원리를 바탕으로 화상병 발병에 적합한 환경 요인을 추론하기 위해서, 최근 4년(2014-2017년) 우리나라 기상관측 자료 및 미래(2020-2100년) 기후변화 시나리오 RCP8.5 예측 기상자료를 입력하여 화상병 발병 예측프로그램인 MARYBLYT로 꽃감염을 예측하였다. 이 예측 프로그램은 신고배 개화기간을 먼저 계산한 후, 개화기간 중 매일매일의 화상병 꽃감염 위험 경보를 출력하였다. 최근 4년 동안 꽃감염 결과 화상병 발생지인 경기 안성과 천안뿐만 아니라 인근 주산지인 평택, 아산 모두 2014년과 2015년에 "Infection" 경보가 나타났다. 또한 배 주산지인 전남 나주는 2016-2017년 "Infection" 경보가 나타났다. 최근 4년간 방제 권고 수준인 "Infection" 또는 "High" 경보 발령은 우리나라 전체 중 80% 지역에서 나타나 우리나라는 화상병 발병에 적합한 환경이었다. 80년간 미래 기후변화 기상자료로 개화기간 동안 화상병 꽃감염을 예측한 결과 해마다 감염위험 지역이 급변하였다. 하루 이상 "Infection" 경보가 발령되는 지역이 전국의 50%가 넘을 정도로 광범위할 것으로 예측되는 해는 총 20년이었던 반면 "Infection" 경보가 전국의 10% 미만 지역일 것으로 예측된 해는 8년이었다. 이들 두 그룹의 환경요인 비교분석 결과, 개화기간 중 평균온도와 누적 강수량이 유의하게 달랐다. 본 연구 결과는 외래 침입균인 화상병 관리를 담당하는 정책 당국에 적절한 정보를 제공할 것이다.

• 한국환경농학회지
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• 제38권4호
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• pp.269-272
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• 2019

BACKGROUND: Since 2015, fire blight disease caused by Erwinia amylovora has been devastating apple and pear orchards every year. To quickly block the disease spreading, infected apple and pear trees have been buried in soil. However, concern on the possibility of the pathogen survival urgently requires informative data on the buried host plants. Therefore, this study was conducted to investigate the survival of the pathogen from the buried host plants. METHODS AND RESULTS: Apple trees buried in 42 months ago in a Jecheon site and pear trees buried in 30 months ago in an Anseong site were excavated using an excavator. Plant samples were taken from stems and twigs of the excavated trees. The collected 120 samples were checked for rotting and used for bacterial isolation, using TSA, R2A, and E. amylovora selection media. The purely isolated bacteria were identified based on colony morphology and 16S rDNA sequences. Wood rotting and decay with off smells and discoloring were observed from the samples. A total of 17 genera and 48 species of bacteria were identified but E. amylovora was not detected. CONCLUSION: Our investigation suggests that the survival of E. amylovora doesn't seem possible in the infected hosts which have been buried in soil for at least 30 months. Therefore, the burial control can be considered as a safe method for fire blight disease.

• The Plant Pathology Journal
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• 제39권1호
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• pp.52-61
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• 2023

Fire blight, caused by Erwinia amylovora, is one of the major bacterial disease of apple and pear, causing enormous economic losses worldwide. Several control measures against E. amylovora have been reported till date, however, none of them have proved to be effective significantly against the pathogen. In this study, mechanisms of the copper-based control agents (CBCAs): copper oxychloride (COCHL), copper oxide (COX), copper hydroxide (CHY), copper sulfate basic (CSB), and tribasic copper sulfate (TCS) and their disease severity reduction efficacy against E. amylovora were analyzed. Bis-1,3-dibutylbarbituric acid trimethine oxonol, carboxyl fluorescein diacetate succinimidyl ester, and 5-cyano-2,3-ditolyl tetrazolium chloride staining were used to check the damage of membrane potential, cytoplasmic pH_in, and respiration of CBCAs-treated E. amylovora, respectively. High disturbance in the membrane potential of E. amylovora was found under COX and COCHL treatments. Similarly, higher significant changes in the inner cytoplasmic pH_in were observed under COX, COCHL, and TCS treatment. CHY and COCHL-treated E. amylovora showed a significant reduction in respiration. In vitro bioassay results revealed that CHY, CSB, and TCS at 2,000 ppm reduced the severity of fire blight both in pre- and post-treatment of CBCAs in immature apple fruits and seedlings. Overall, the most effective CBCAs against E. amylovora could be CHY at 2,000 ppm as its showed inhibition mechanisms and disease severity reduction.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2021년도 춘계학술대회
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• pp.23-23
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• 2021

Apple (Malus×domestica Borkh.; Rosaceae) is an important fruit crop grown mainly in temperate regions of the world. Tissue culture in vitro is a biotechnological technique that has been used to genetically improve cultivars (scions) and rootstocks. This could be important in the production of genetically uniform scions and rootstocks for commercial apple production. In nurseries, apple plants are produced by grafting scions onto rootstocks. The Cornell-Geneva (Geneva® series) breeding program has bred several dwarf rootstocks that are resistant to diseases and pests and are also cold hardy. This study was conducted to determine the optimal medium strength to improve sprouting shoot rate of apical meristem of the apple rootstocks of fire blight resistance. The apple rootstocks apical meristem at size (0.2 mm to 0.3 mm) with axillary buds were cultured on the MS(Murashige & Skoog) medium supplemented with plant growth regulators. The sprouting ratio and growth characteristics was evaluated after eight weeks in vitro culture. The highest rate of bud differentiation and shoot formation were 23.8% and 55.6%, respectively. After 6 weeks, shoots were regenerated from apical meristem, and their growth characteristics was significantly varied on the respective basal medium with different plant growth regulators. Our studies showed that the apple rootstocks the apple rootstocks of fire blight resistance plantlets could be successfully produced from apical meristem differentiated out of young twigs via organogenic regeneration.

• 농업과학연구
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• 제50권2호
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• pp.241-247
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• 2023

Erwinia amylovora , which causes fire blight disease on apple and pear trees, is one of the most important phytopathogens because of its devastating impact. Currently, the only way to effectively control fire blight disease is through the use of antibiotics such as streptomycin, kasugamycin, or oxytetracycline. However, problems with the occurrence of resistant strains due to the overuse of antibiotics are constantly being raised. It is therefore necessary to develop novel disease control methods through an advanced understanding of the pathogenesis mechanism of E. amylovora . To better understand the pathogenesis of E. amylovora , we investigated unknown virulence factors by random mutagenesis and screening. Random mutants were generated by Tn5 transposon insertion, and the pathogenicity of the mutants was assessed by inoculation of the mutants on apple fruitlets. A total of 17 avirulent mutants were found through screening of 960 random mutants. Among them, 14 mutants were already reported as non-pathogenic strains, while three mutants, TS3128_M2899 (ΔSUFU ), TS3128_M2939 (ΔwcaG ), and TS3128_M3747 (ΔrecB ), were not reported. Further study of the association between E. amylovora pathogenicity and these 3 novel genes may provide new insight into the development of control methods for fire blight disease.

• The Plant Pathology Journal
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• 제37권4호
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• pp.396-403
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• 2021

Fire blight disease, caused by Erwinia amylovora, could damage rosaceous plants such as apples, pears, and raspberries. In this study, we designed to understand how E. amylovora affected other bacterial communities on apple rhizosphere; twig and fruit endosphere; and leaf, and fruit episphere. Limited studies on the understanding of the microbial community of apples and changes the community structure by occurrence of the fire blight disease were conducted. As result of these experiments, the infected trees had low species richness and operational taxonomic unit diversity when compared to healthy trees. Rhizospheric bacterial communities were stable regardless of infection. But the communities in endosphere and episphere were significanlty affected by E. amylovora infection. We also found that several metabolic pathways differ significantly between infected and healthy trees. In particular, we observed differences in sugar metabolites. The finding provides that sucrose metabolites are important for colonization of E. amylovora in host tissue. Our results provide fundamental information on the microbial community structures between E. amylovora infected and uninfected trees, which will contribute to developing novel control strategies for the fire blight disease.

• The Plant Pathology Journal
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• 제37권4호
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• pp.404-412
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• 2021

Despite the plant microbiota plays an important role in plant health, little is known about the potential interactions of the flower microbiota with pathogens. In this study, we investigated the microbial community of apple blossoms when infected with Erwinia amylovora. The long-read sequencing technology, which significantly increased the genome sequence resolution, thus enabling the characterization of fire blight-induced changes in the flower microbial community. Each sample showed a unique microbial community at the species level. Pantoea agglomerans and P. allii were the most predominant bacteria in healthy flowers, whereas E. amylovora comprised more than 90% of the microbial population in diseased flowers. Furthermore, gene function analysis revealed that glucose and xylose metabolism were enriched in diseased flowers. Overall, our results showed that the microbiome of apple blossoms is rich in specific bacteria, and the nutritional composition of flowers is important for the incidence and spread of bacterial disease.

• The Plant Pathology Journal
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• 제38권3호
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• pp.248-253
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• 2022

Erwinia amylovora is a devastating bacterial plant pathogen that infects Rosaceae including apple and pear and causes fire blight. Bacteriophages have been considered as a biological control agent for preventing bacterial infections of plants. In this study, nine bacteriophages (ΦFifi011, ΦFifi044, ΦFifi051, ΦFifi067, ΦFifi106, ΦFifi287, ΦFifi318, ΦFifi450, and ΦFifi451) were isolated from soil and water samples in seven orchards with fire blight in Korea. The genetic diversity of bacteriophage isolates was confirmed through restriction fragment length polymorphism pattern analysis. Host range of the nine phages was tested against 45 E. amylovora strains and 14 E. pyrifoliae strains and nine other bacterial strains. Among the nine phages, ΦFifi044 and ΦFifi451 infected and lysed E. amylovora only. And the remaining seven phages infected both E. amylovora and E. pyrifoliae. The results suggest that the isolated phages were different from each other and effective to control E. amylovora, providing a basis to develop biological agents and utilizing phage cocktails.

• 한국균학회지
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• 제51권4호
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• pp.447-460
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• 2023

식물병원 세균 Erwinia amylovora 의해 발생하는 과수화상병은 사과, 배 등 장미과에 속하는 식물에 심한 피해를 주고 있다. 병의 빠른 확산을 막기 위해 국내에서는 병이 발생한 사과나무와 배나무에 대해 매몰하는 병관리를 실시해 왔다. 방제방법의 안전성을 입증하기 위해 매몰한 이병식물과 이병식물 주변의 토양을 조사하였다. 매몰토양 미생물군 조사과정에서 Bisifusarium allantoides, Botryotrichum Domesticum, Microascus verrucosus, Paraphoma pye, Phaeosphaeria culmorum, Ramophialophora globispora, Sordaria tomentoalba, Striaticonidium brachysporum 등이 국내 미기록종으로 확인되었다. 이에 이들 8종 진균에 대한 형태학적, 분자유전학적 특성을 보고한다.

• The Plant Pathology Journal
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• 제34권5호
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• pp.445-450
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• 2018

Bacteriophages, bacteria-infecting viruses, have been recently reconsidered as a biological control tool for preventing bacterial pathogens. Erwinia amylovora and E. pyrifoliae cause fire blight and black shoot blight disease in apple and pear, respectively. In this study, the bacteriophage phiEaP-8 was isolated from apple orchard soil and could efficiently and specifically kill both E. amylovora and E. pyrifoliae. This bacteriophage belongs to the Podoviridae family. Whole genome analysis revealed that phiEaP-8 carries a 75,929 bp genomic DNA with 78 coding sequences and 5 tRNA genes. Genome comparison showed that phiEaP-8 has only 85% identity to known bacteriophages at the DNA level. PhiEaP-8 retained lytic activity up to $50^{\circ}C$, within a pH range from 5 to 10, and under 365 nm UV light. Based on these characteristics, the bacteriophage phiEaP-8 is novel and carries potential to control both E. amylovora and E. pyrifoliae in apple and pear.