• The Plant Pathology Journal
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• 제34권3호
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• pp.191-198
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• 2018

Fast and accurate diagnosis is needed to eradicate and manage economically important and invasive diseases like fire blight. Loop-mediated isothermal amplification (LAMP) is known as the best on-site diagnostic, because it is fast, highly specific to a target, and less sensitive to inhibitors in samples. In this study, LAMP assay that gives more consistent results for on-site diagnosis of fire blight than the previous developed LAMP assays was developed. Primers for new LAMP assay (named as DS-LAMP) were designed from a histidine-tRNA ligase gene (EAMY_RS32025) of E. amylovora CFBP1430 genome. The DS-LAMP amplified DNA (positive detection) only from genomic DNA of E. amylovora strains, not from either E. pyrifoliae (causing black shoot blight) or from Pseudomonas syringae pv. syringae (causing shoot blight on apple trees). The detection limit of DS-LAMP was 10 cells per LAMP reaction, equivalent to $10^4$ cells per ml of the sample extract. DS-LAMP successfully diagnosed the pathogens on four fire-blight infected apple and pear orchards. In addition, it could distinguish black shoot blight from fire blight. The $B{\ddot{u}}hlmann$-LAMP, developed previously for on-site diagnosis of fire blight, did not give consistent results for specificity to E. amylovora and on-site diagnosis; it gave positive reactions to three strains of E. pyrifoliae and two strains of P. syringae pv. syringae. It also, gave positive reactions to some healthy sample extracts. DS-LAMP, developed in this study, would give more accurate on-site diagnosis of fire blight, especially in the Republic of Korea, where fire blight and black shoot blight coexist.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2020년도 추계국제학술대회
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• pp.48-48
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• 2020

Fire blight, caused by Erwinia amylovora(Burrill), is a destructive disease of apple that damages blossoms, shoots, and woody plant organs. The fire blight disease is a worldwide problem for pome fruit growers because all popular apple cultivars are susceptible to the disease. Recently, fire blight of apple rootstocks has become a serious economic problem in high-density orchard systems in korea. The most commonly used dwarfing root stocks, M.9 and M.26, are highly susceptible to E. amylovora. The objective of the apple rootstock-breeding program has been to develop pomologically excellent rootstocks with resistance to abiotic and biotic stresses, including fire blight. Budagovsky 9 (B.9) apple rootstock is reported to be highly susceptible when inoculated with E. amylovora, although results from multiple trials showed that B.9 is resistant to rootstock blight infection in field plantings. So we tried to collect the apple rootstocks traits of fire blight resistance. The apple genotype Malus Robusta 5 (MR5) represents an ideal donor for fire blight resistance because it was described as resistant to all currently known European strains of the pathogen. The PCR for detecting the MR5 gene using the primers Md_MR5_FL_F/Md_MR5_FL_R. The results of these experiments confirmed some apple rootstocks traits of fire blight resistance showed the MR5. Furthermore, this gene is confirmed to be the resistance determinant of Mr5 as the transformed lines undergo the same gene-for-gene interaction in the host-pathogen relationship MR5-E. amylovora.

• The Plant Pathology Journal
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• 제39권5호
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• pp.504-512
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• 2023

After transitioning from periodic to model-based control policy for fire blight blossom infection, it is crucial to provide the timing of field application with easy and accurate information. To assess the risk of blossom infection, Maryblyt was employed in 31 sites across apple-producing regions nationwide, including areas prone to fire blight outbreaks, from 2021 to 2023. In 2021 and 2023, two and seven sites experienced Blossom Infection Risk-Infection warning occurrences among 31 sites, respectively. However, in 2022, most of the sites observed Blossom Infection Risk-Infection from April 25 to 28, highlighting the need for blossom infection control. For the comparison between the two model-based control approaches, we established treatment 1, which involved control measures according to the Blossom Infection Risk-Infection warning and treatment 2, aimed at maintaining the Epiphytic Infection Potential below 100. The analysis of control values between these treatments revealed that treatment 2 was more effective in reducing Blossom Infection Risk-Infection and the number of days with Epiphytic Infection Potential above 100, with respective averages of 95.6% and 93.0% over the three years. Since 2022, the implementation of the K-Maryblyt system and the deployment of Automated Weather Stations capable of measuring orchard weather conditions, with an average of 10 stations per major apple fire blight county nationwide, have taken place. These advancements will enable the provision of more accurate and timely information for farmers based on fire blight models in the future.

• 농업과학연구
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• 제47권2호
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• pp.349-360
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• 2020

Fire-blight disease is a kind of contagious disease affecting apples, pears, and some other members of the family Rosaceae. Due to its extremely strong infectivity, once an orchard is confirmed to be infected, all of the orchards located within 100 m must be buried under the ground, and the sites are prohibited to cultivate any fruit trees for 5 years. In South Korea, fire-blight was confirmed for the first time in the Ansung area in 2015, and the infection is still being identified every year. Traditional approaches to detect fire-blight are expensive and require much time, additionally, also the inspectors have the potential to transmit the pathogen, Thus, it is necessary to develop a remote, unmanned monitoring system for fire-blight to prevent the spread of the disease. This study was conducted to detect fire-blight on pear trees using discriminant analysis with color information collected from a rotary-wing drone. The images of the infected trees were obtained at a pear orchard in Cheonan using an RGB camera attached to a rotary-wing drone at an altitude of 4 m, and also using a smart phone RGB camera on the ground. RGB and Lab color spaces and discriminant analysis were used to develop the image processing algorithm. As a result, the proposed method had an accuracy of approximately 75% although the system still requires many flaws to be improved.

• The Plant Pathology Journal
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• 제38권5호
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• pp.461-471
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• 2022

Erwinia amylovora is a causative pathogen of fire blight disease, affecting apple, pear, and other rosaceous plants. Currently, management of fire blight relies on cultural and chemical practices, whereas it has been known that few biological resources exhibit disease control efficacy against the fire blight. In the current study, we found that an SFC20201208-M01 fungal isolate exhibits antibacterial activity against E. amylovora TS3128, and the isolate was identified as a Penicillium brasilianum based on the 𝛽-tubulin (BenA) gene sequence. To identify active compounds from the P. brasilianum culture, the culture filtrate was partitioned with ethyl acetate and n-butanol sequentially. From the ethyl acetate layer, we identified two new compounds (compounds 3-4) and two known compounds (compounds 1-2) based on spectroscopic analyses and comparison with literature data. Of these active compounds, penicillic acid (1) exhibited promising antibacterial activity against E. amylovora TS3128 with a minimal inhibitory concentration value of 25 ㎍/ml. When culture filtrate and penicillic acid (125 ㎍/ml) were applied onto Chinese pearleaf crab apple seedlings prior to inoculation of E. amylovora TS3128, the development of fire blight disease was effectively suppressed in the treated plants. Our results provide new insight into the biocontrol potential of P. brasilianum SFC20201208-M01 with an active ingredient to control fire blight.

• 식물병연구
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• 제23권4호
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• pp.306-313
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• 2017

최근 한국에서 화상병이 발생하였으며, 그 이후로 이병에 대한 박멸프로그램이 가동되고 있다. 본 연구에서는 2가지 항혈청기반 진단 스트립의 국내 분리 화상병균 Erwinia amylovora (Ea)에 대한 특이성과 검출민감도 그리고 현장진단에 적용을 평가하였다. 상업화된 Ea AgriStrip과 본 연구에서 개발한 EB strip은 검정에 사용한 모든 한국 Ea 균주들과 가지검은마름병을 일으키는 대부분의 Erwinia pyrifoliae (Ep)에 양성반응을 보여주었다. 사과나무 가지마름병을 일으키는 Pusedomonas syringae pv. syringae (Pss)의 사용한 모든 균주에 음성반응을 보여주었다. 2 스트립 사이에 검출민감도는 유사하였다. 현장진단의 경우, 2가지 스트립은 화상병이 발생한 모든 과수원에서 채취한 화상병징 세균추출액에 대하여 양성반응을 보였다. 그러나 겨울철에 진행된 한 곳의 화상병 현장진단에서는 화상병병징 세균추출액에 음성반응을 보였다. 또한 2가지 스트립은 가지검은마름병이 발생한 과수원에서 채집한 가지검은마름병징 세균추출액에 대해서 양성반응을 보여주었다. 이상의 결과는 Ea AgriStrip과 EB strip이 화상병 현장진단에 유용할 것으로 암시한다.

• The Plant Pathology Journal
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• 제37권6호
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• pp.543-554
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• 2021

To preventively control fire blight in apple trees and determine policies regarding field monitoring, the Maryblyt ver. 7.1 model (MARYBLYT) was evaluated in the cities of Chungju, Jecheon, and Eumseong in Korea from 2015 to 2020. The number of blossom infection alerts was the highest in 2020 and the lowest in 2017 and 2018. And the common feature of MARYBLYT blossom infection risks during the flowering period was that the time of BIR-High or BIR-Infection alerts was the same regardless of location. The flowering periods of the trees required to operate the model varied according to the year and geographic location. The model predicts the risk of "Infection" during the flowering periods, and recommends the appropriate times to control blossom infection. In 2020, when flower blight was severe, the difference between the expected date of blossom blight symptoms presented by MARYBLYT and the date of actual symptom detection was only 1-3 days, implying that MARYBLYT is highly accurate. As the model was originally developed based on data obtained from the eastern region of the United States, which has a climate similar to that of Korea, this model can be used in Korea. To improve field utilization, however, the entire flowering period of multiple apple varieties needs to be considered when the model is applied. MARYBLYT is believed to be a useful tool for determining when to control and monitor apple cultivation areas that suffer from serious fire blight problems.

• The Plant Pathology Journal
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• 제38권4호
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• pp.355-365
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• 2022

Erwinia amylovora and E. pyrifoliae are the causative agents of destructive diseases in both apple and pear trees viz. fire blight and black shoot blight, respectively. Since the introduction of fire blight in Korea in 2015, the occurrence of both pathogens has been independently reported. The co-incidence of these diseases is highly probable given the co-existence of their pathogenic bacteria in the same trees or orchards in a city/district. Hence, this study evaluated whether both diseases occurred in neighboring orchards and whether they occurred together in a single orchard. The competition and virulence of the two pathogens was compared using growth rates in vitro and in planta. Importantly, E amylovora showed significantly higher colony numbers than E. pyrifoliae when they were co-cultured in liquid media and co-inoculated into immature apple fruits and seedlings. In a comparison of the usage of major carbon sources, which are abundant in immature apple fruits and seedlings, E. amylovora also showed better growth rates than E. pyrifoliae. In virulence assays, including motility and a hypersensitive response (HR), E. amylovora demonstrated a larger diameter of travel from the inoculation site than E. pyrifoliae in both swarming and swimming motilities. E. amylovora elicited a HR in tobacco leaves when diluted from 1:1 to 1:16 but E. pyrifoliae does not elicit a HR when diluted at 1:16. Therefore, E. amylovora was concluded to have a greater competitive fitness than E. pyrifoliae.

• 식물병연구
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• 제26권4호
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• pp.239-249
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• 2020

2019년 국내의 사과와 배에 화상병이 크게 발생한 원인을 파악하기 위하여 화상병 발생한 30개 과원을 대상으로 각각의 발생 상황과 농가 면담을 통해 경종적 특징 등을 조사하였다. 화상병은 이미 감염된 지 2년 이상 오래 된 과원에서 대부분 발생하였는데, 이런 원인은 (1) 농가가 병 증상을 정확히 알지 못하여 농작업과 방화곤충 등을 통해 과원 내에서 퍼지게 되고, (2) 방화곤충이나 농작업자 등에 의해 처음 발생 과원에서 주변 과수원으로 확산되었고, (3) 동일 경작자 또는 공동 농작업자에 의해 근거리 또는 원거리로 확산된 것이라고 추정할 수 있다. (4) 이런 일련의 과정이 새롭게 확산된 지역에서 반복되다가 농가들이 화상병을 알게 되면서 신고가 증가한 것이 2019년 화상병 대발생의 일련의 원인이라고 추정할 수 있었다. 국내에서 화상병 확산을 최소화하기 위해서는 조기진단을 위한 철저한 농업인 교육과 무병징 식물체에서도 화상병균 진단이 가능한 정량적 검출기술이 요구되고 있다. 또한 큰 열매를 주로 생산하는 국내 재배법에 적합한 약제방제 체계 개발이 필요하다. 화상병 방제에서 가장 중요한 가지의 궤양 증상, 묘목, 양봉장 등의 전염원 관리를 위해서 과원별 병원균의 분자역학연구를 통해 정확한 확산경로를 구명할 것을 제안한다.

• 식물병연구
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• 제26권4호
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• pp.222-228
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• 2020

과수 화상병을 일으키는 Erwinia amylovora는 국내에서 금지병원균으로 지정되어 화상병 발생 시, 중앙 정부의 진단을 근거로 기주를 매몰하는 공적 방제가 실시되고 있다. 국내 과수 화상병은 2015년 안성, 천안 및 제천의 43농가에서 발생하여 42.9 ha를 매몰한 것을 시작으로, 2019년 발생 지역이 11개 시군으로 확산되었으며, 총 348농가 260.4 ha가 매몰되었다. 배나무 화상병은 주로 경기남부와 충남에서 발생되었고, 발생 건수가 연평균 29±9.2건으로 매년 비교적 고르게 발생되었으며 20-30년생 과수에서 발병 비율이 가장 높았다. 반면, 사과나무 화상병은 주로 경기북부, 강원, 충북에서 발생되었고, 발생 건수가 연평균 41±57.6건으로 2018-2019년 발생건수가 크게 증가하였으며, 20년 이하의 과수의 발병 비율이 높았다. 국내 과수 화상병은 어린 사과나무에서 병의 확산이 빠르므로, 특히 미성숙 과수가 식재된 과원에서는 화상병이 발병하지 않도록 약제를 적기에 살포하는 등 예방을 철저히 하고, 발병 시 신속히 방제해야 한다.