• The Plant Pathology Journal
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• 제40권5호
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• pp.525-536
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• 2024

Agrochemicals containing antibiotics are authorized to manage fire blight that has been occurring in Korea since 2015. The minimum inhibitory concentration (MIC) of each antibiotic against Erwinia amylovora, the causal pathogen of fire blight, has increased over the years due to the pathogen's frequent exposure to antibiotics, indicating the necessity to prepare for the emergence of antibiotic resistance. In this study, E. amylovora was exposed to stepwise increasing concentrations of eight different agrochemicals, each containing single or mixed antibiotics, and gene mutation and changes in MIC were assessed. Streptomycin and oxolinic acid induced an amino acid substitution in RpsL and GyrA, respectively, resulting in a rapid increase in MIC. Oxytetracycline initially induced amino acid substitutions or frameshifts in AcrR, followed by substitutions of 30S small ribosomal protein subunit S10 or AcrB, further increasing MIC. E. amylovora acquired resistance in the order of oxolinic acid, streptomycin, and oxytetracycline at varying exposure frequencies. Resistance acquisition was slower against agrochemicals containing mixed antibiotics than those with single antibiotics. However, gene mutations conferring antibiotic resistance emerged sequentially to both antibiotics in the mixed formulations. Results suggested that frequent application of mixed antibiotics could lead to the emergence of multidrug-resistant E. amylovora isolates. This study provided essential insights into preventing the emergence of antibiotic-resistant E. amylovora and understanding the underlying mechanisms of resistance acquisition.

• The Plant Pathology Journal
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• 제35권3호
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• pp.219-233
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• 2019

Soybean cultivars susceptible to Phytophthora root and stem rot are vulnerable to seed rot and damping-off of seedlings and young plants following an infection by Phytophthora sojae. In this study, the disease responses of Japanese soybean cultivars including currently grown main cultivars during the early growth stages were investigated following infections by multiple P. sojae isolates from Japanese fields. The extent of the resistance to 17 P. sojae isolates after inoculations at 14, 21, and 28 days after seeding varied significantly among 18 Japanese and two US soybean cultivars. Moreover, the disease responses of each cultivar differed significantly depending on the P. sojae isolate and the plant age at inoculation. Additionally, the treatment of 'Nattosyo-ryu' seeds with three fungicidal agrochemicals provided significant protection from P. sojae when plants were inoculated at 14-28 days after seeding. These results indicate that none of the Japanese soybean cultivars are completely resistant to all tested P. sojae isolates during the first month after sowing. However, the severity of the disease was limited when plants were inoculated during the later growth stages. Furthermore, the protective effects of the tested agrochemicals were maintained for at least 28 days after the seed treatment. Japanese soybean cultivars susceptible to Phytophthora root and stem rot that are grown under environmental conditions favorable for P. sojae infections require the implementation of certain practices, such as seed treatments with appropriate agrochemicals, to ensure they are protected from P. sojae during the early part of the soybean growing season.

• 아시안잔디학회지
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• 제20권2호
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• pp.191-201
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• 2006

퍼팅 그린의 한지형 잔디에 많은 문제가 되고 있는 동전마름병은 Sclerotinia homeocarpa에 의해 발생한다. 본 연구에서는 미생물 제제를 이용한 생물학적 방제법을 통하여 동전마름병을 방제하고자 전국의 골프장과 산, 밭 토양에서 길항 미생물을 분리하였다. 길항 미생물은 동전마름병의 병원균인 S. homeocarpa에 대한 항균활성 및 균사 생장 억제력, 배양성 등을 고려하여 선발하였고, 폿트와 퍼팅 그린의 예비 묘포지에서의 생물 검정 실험을 통하여 효력을 검정하였다. 선발된 미생물은 Bacillus subtilis EW42-1과 Trichoderma harzianum GBF-0208이었고, 생물 검정 실험 결과 화학 농약 대조구인 터부코나졸 유제와 대비하여 높은 방제 효과를 보였다.

• Applied Biological Chemistry
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• 제42권4호
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• pp.356-360
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• 1999

감귤저장 방법의 개선과 감귤 껍질의 효율적인 활용을 위해서 시판 중인 농약제제와 감귤정유의 감귤부패 관련 사상균에 대한 살균 작용을 조사하였다. Alternaria alternata, Rhizopus sp., Botrytis cinerea, Monilia candida, Penicillium italicum, Penicillium digitatum 등 6종의 사상균에 대한 시판 합성 농약제제 11종의 생육저해 효과를 조사한 결과, mancozeb 또는 fluazinam을 함유한 제제의 활성 범위가 가장 넓었고, conazole 계통의 화합물이 중간 정도의 활성 범위를 나타내었으며, iprodione, benomyl, azoxtrobin 또는 thiophanate을 함유한 제제의 항균활성 범위가 가장 좁은 것으로 나타났다. 농약제제의 생육저해 효과는 대상 균주에 따라 달랐으며, Penicillium italicum과 Alternaria alternata는 각종 살균제의 처리에 대한 생존력이 비교적 강하였다. 감귤정유를 상기 6개 균주의 포자와 각각 접촉시켰을 때는 그 어느 균주의 생존 포자도 검출되지 않았으며, 감귤정유의 살균력은 paper disk법과 현미경 관찰로도 증명되었다. 이는 감귤정유가 광범위한 살균력을 지니고 있음을 제시한다. 따라서 감귤 정유를 감귤저장에 활용하는 방법을 검토할 필요가 있다.

• The Plant Pathology Journal
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• 제39권4호
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• pp.351-360
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• 2023

Citrus melanose, caused by Diaporthe citri, has been one of the serious diseases, and chemical fungicides were used for protection in many citrus orchards of Jeju Island. Establishing a disinfectant resistance management system and reducing pesticide usage would be important for contributing to safe agricultural production. In this study, monitoring of chemical resistance was performed with 40 representative D. citri isolates from many citrus orchards in Jeju Island. Four different fungicides, kresoxim-methyl, benomyl, fluazinam, and prochloraz manganese, with seven different concentrations were tested in vitro by growing the mycelium of the fungal isolates on the artificial medium potato dextrose agar. Among the 40 fungal isolates, 12 isolates were investigated as resistant to kresoxim-methyl which could not inhibit the mycelium growth to more than 50%. Especially isolate NEL21-2 was also resistant against benomyl, whose hyphae grew well even on the highest chemical concentration. However, any chemical resistance of fungal isolates was found against neither fluazinam nor prochloraz manganese. On the other hand, in vivo bio-testing of some resistant isolates was performed against both kresoxim-methyl and benomyl on young citrus leaves. Typical melanose symptoms developed on the citrus leaves pre-treated with both agrochemicals after inoculation with the resistant isolates. However, no or less symptoms were observed when the susceptible isolates were inoculated. Based on these results, it was suggested that some resistant isolates of D. citri occurred against both systemic fungicides, which may be valuable to build a strategy for protecting citrus disease.

• The Plant Pathology Journal
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• 제29권2호
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• pp.201-208
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• 2013

Drought stress is one of the major yield affecting factor for pepper plant. The effects of PGPRs were analyzed in relation with drought resistance. The PGPRs inoculated pepper plants tolerate the drought stress and survived as compared to non-inoculated pepper plants that died after 15 days of drought stress. Variations in protein and RNA accumulation patterns of inoculated and non-inoculated pepper plants subjected to drought conditions for 10 days were confirmed by two dimensional polyacrylamide gel electrophoresis (2D-PAGE) and differential display PCR (DD-PCR), respectively. A total of six differentially expressed stress proteins were identified in the treated pepper plants by 2D-PAGE. Among the stress proteins, specific genes of Cadhn, VA, sHSP and CaPR-10 showed more than a 1.5-fold expressed in amount in B. licheniformis K11-treated drought pepper compared to untreated drought pepper. The changes in proteins and gene expression patterns were attributed to the B. licheniformis K11. Accordingly, auxin and ACC deaminase producing PGPR B. licheniformis K11 could reduce drought stress in drought affected regions without the need for overusing agrochemicals and chemical fertilizer. These results will contribute to the development of a microbial agent for organic farming by PGPR.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.30-31
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• 2003

Total 291 isolates of Ampelomyces quisqualis were obtained from 32 species of powdery mildew fungi and a selected isolate, Ampelomyces quisqualis 94013 (AQ94013) effectively hyperparasitized 6 species of Sphaerotheca and one species of Erysiphe which cause serious damage on many important crops in Korea. Moreover, AQ94013 showed antagonistic effects against 12 major fungal plant pathogens as well. Results indicated that the present isolate is not a host specific hyperparasite and has a broad spectrum of biocontrol potential. Providentially, AQ94013 revealed resistance to a number of agrochemicals so as to be applied with the chemicals reciprocally.(중략)

• 식물병연구
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• 제12권3호
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• pp.260-266
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• 2006

Pythium spp. 균에 의해 발생되는 피시움마름병(Pythium blight)은 골프장 퍼팅 그린에서 문제가 되는 대표적 병해이다. 본 연구에서는 Pythium aphanidermatum를 피시움마름병 병원균으로 하여 생물학적 방제법에 이용할 수 있는 길항 미생물을 1차 선발하였고, 선발된 길항 미생물에 대해 폿트 수준의 생물 검정 실험을 실시하였다. 두 실험을 동해 선발된 미생물 중에서 Relative Performance Indies 값을 기준으로 가장 우수한 것을 선별하여 피시움마름병에 대한 길항 미생물로 최종 선발하였고, 동정한 결과 Bacillus subtilis로 밝혀졌다. 최종 선발된 미생물은 B. subtilis GB-0365라 명명하였고, 화학 농약에 대한 내성 실험과 혼용 처리에 따른 효과를 검정하여 화학 농약과 시간의 차이를 두고 교호 살포할 경우 방제효과가 보다 높게 나타났다. 골프장의 간이 묘포장에서 자연 발생된 피시움마름병에 대한 B. subtilis GB-0365의 방제효과를 검증한 결과, 무처리 대비 방제가는 56.4%, 화학 농약 대비 방제가는 60.9%로 우수한 방제 효과을 가진 것으로 판명되었다.

• Journal of Multimedia Information System
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• 제7권2호
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• pp.189-196
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• 2020

We have developed a device for recording biological data by inserting three electrodes and a needle with an angular velocity sensor into the moth for the purpose of measuring the electromyogram of the flapping and the corresponding lift force. With this measurement, it is possible to evaluate the moth-physiological function of moths, and the amount of pesticides that insects are exposed to (currently LD50-based standards), especially the amount of chronic low-concentration exposure, can be reduced the dose. We measured and recorded 2-channel electromyography (EMG) and angular velocity corresponding to pitch angle (pitch-like angle) associated with wing flapping for 100 sweet potato hawkmoths (50 females and 50 males) with the animals suspended and constrained in air. Overall, the angular velocity and amplitude of EMG signals demonstrated high correlation, with a correlation coefficient of R = 0.792. In contrast, the results of analysis performed on the peak-to-peak (PP) EMG intervals, which correspond to the RR intervals of ECG signals, indicated a correlation between ΔF fluctuation and angular velocity of R = 0.379. Thus, the accuracy of the regression curve was relatively poor. Using a DC amplification circuit without capacitive coupling as the EMG amplification circuit, we confirmed that the baseline changes at the gear change point of wing flapping. The following formula gives the lift provided by the wing: angular velocity × thoracic weight - air resistance - (eddy resistance due to turbulence). In future studies, we plan to attach a micro radio transmitter to the moths to gather data on potential energy, kinetic energy, and displacement during free flight for analysis. Such physiological functional evaluations of moths may alleviate damage to insect health due to repeated exposure to multiple agrochemicals and may lead to significant changes in the toxicity standards, which are currently based on LD50 values.

• 한국응용곤충학회지
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• 제25권1호
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• pp.27-32
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• 1986

벼줄기굴파리에 대한 저항성(抵抗性) 검정방법(檢定方法)을 확립하고 주요 품종의 저항성정도들 알기 위하여 포장과 폿트에서 피해(被害)와 사충율(死蟲率)을 조사한 결과, 1. 포장에서 다수계품종(多收系品種)이 일반계품종(一般系品種)보다 피해가 심하였고, 1, 2화기 피해간에는 고도(高度)의 정(正)의 상관관계(相關關係) ($r=0.845^{**}$)가 있었다. 2. 산란선호성(産卵選好性)은 품종간에 유의성(有意性)이 없었다. 3. 유충의 경내(莖內) 침입율(侵入率)은 수도 생육이 진전됨에 따라 낮아졌다. 4. 품종 저항성(抵抗性) 기작(機作)은 주로 항충성(抗蟲性)(antibiosis)에 기인된 것으로 추정되었다. 5. 품종별 피해엽수(被害葉數)와 사충율(死蟲率)간에는 고도(高度)의 부(負)의 상관관계(相關關係)('81년:$r=-0.884^{**}$, '82년:$r=-0.919^{**}$)가 있었다. 6. 품종저항성(品種抵抗性) 검정(檢定)은 파종 $30{\sim}40$일 된 묘에 갓부화한 유충을 접종하고, 접종 20일후에 사충율(死蟲率)을 조사하는 것이 합리적이었다. 7. 저항성품종(抵抗性品種)은 낙동벼, 진주벼, 추청벼 등이고, 감수성품종(感受性品種)은 금강벼, 밀양 23호, 백양벼, 밀양 30호 등이다.