• The Plant Pathology Journal
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• 제16권3호
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• pp.156-161
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• 2000

A wilt disease occurred on greenhouse-grown eggplants at Yeojoo, Korea in 1997. The wilted eggplants had leaves with gradual yellowing, interveinal necrosis, and marginal crinkling. Vascular tissues of diseased stems were discolored, turned black, and microsclerotia developed at the base of stems. The disease progressed from lower parts of the plants upward. Fungal isolates from discolored vascular tissues were initially whitish to cream color on potato-dextrose agar (PDA) plate, which later turned black due to the formation of microsclerotia. Conidiophores were erect, hyaline, verticillately branched, and had 3 or 4 phialides arising at each node. Phialides were hyaline, arranged in whorls, and measured as 17.5-32.5 x 2-3$\mu\textrm{m}$. Conidia were hyaline, ellipsoidal to sub-cylindrical, mainly one-celled, and measured as 5-8.8 x 2-4$\mu\textrm{m}$. Conidia were borne in small clusters at the tips of phialides. Microsclerotia formed on PDA plates, and consisted of globular cells that formed irregular masses of various shapes. Chlamydospores were absent. Based on these cultural and morphological characteristics, the fungus was identified as Verticillium dahliae Klebahn. Pathogenicity tests by root cutting, root dipping or soil drenching resulted in similar symptoms observed in the naturally infected eggplants. This is the first report on occurrence of Verticillium wilt of eggplant in Korea.

• Parasites, Hosts and Diseases
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• 제56권3호
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• pp.291-294
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• 2018

Soil-transmitted helminthiases (STH) are now no longer public health problems in the Republic of Korea (South Korea), but their status are unavailable in the residents of North Korea (NK) despite the expectation of large scale traffic and future reunification of the Korean Peninsula. A total of 20 female refugees from NK who had been admitted to the Division of Gastroenterology, Dankook University Hospital, were subjected in this study. Among them, 15 refugees were examined by the colonoscopy and 10 ones were examined with the stool examination (formalin-ether sedimentation). Both diagnostic methods were commonly adopted in 5 patients. Eggs of Trichuris trichiura were detected in 7 out of 10 refugees in the stool examination. In the colonoscopy, T. trichiura worms were found in 6 (40.0%) out of 15 refugees. Total 9 (45.0%) peoples were confirmed to be infected with human whipworms. Additionally, 1 case of clonorchiasis was diagnosed in the stool examination and a worm of Ascaris lumbricoides was discovered from a trichuriasis case. These findings suggested that STH is highly prevalent in NO, in which living conditions are not so good in the aspect of general hygiene and medical care.

• The Plant Pathology Journal
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• 제27권1호
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• pp.78-84
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• 2011

Antagonistic rhizobacteria, more specifically fluorescent pseudomonads and certain species of Bacillus, are known as biocontrol agents of fungal root diseases of agronomic crops. In this study, 144 bacteria were isolated from cucumber rhizosphere and screened as potential biological control agents against Phytophthora drechsleri, the causal agent of cucumber root rot, in vitro condition. Non-volatile compounds of 23 isolates showed noticeable inhibition zone (> 30%) against P. drechsleri, whereas volatile compounds of 7 isolates could prevent more than 30% of the mycelial growth of the fungus. All promising isolates, except of Pseudomonas flourescens V69, promoted significantly plant growth under in vitro condition. P. flourescens CV69 and V11 exhibited the highest colonization on the root. Results of the greenhouse studies showed that a reduction in disease incidence by use of some strains, and particularly use of strains CV6 and V11 as a soil treatment, exhibited a reduction in disease incidence so that suppressed disease by 85.71 and 69.39% respectively. Pseudomonas flourescens CV6 significantly suppressed disease in comparison to Ridomil fungicide. The use of mixture bacterial strains in the soil inoculated by the fungus resulting in falling down the most of the plants which didn't show significant difference with infected control soils without bacteria.

• The Plant Pathology Journal
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• 제38권5호
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• pp.490-502
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• 2022

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) disease in rice (Oryza sativa L.) and it is among the most destructive pathogen responsible for severe yield losses. Potential bacterial biocontrol agents (BCAs) with plant growth promotion (PGP) abilities can be applied to better manage the BLB disease and increase crop yield, compared to current conventional practices. Thus, this study aimed to isolate, screen, and identify potential BCAs with PGP abilities. Isolation of the BCAs was performed from internal plant tissues and rhizosphere soil of healthy and Xoo-infected rice. A total of 18 bacterial strains were successfully screened for in vitro antagonistic ability against Xoo, siderophore production and PGP potentials. Among the bacterial strains, 3 endophytes, Bacillus sp. strain USML8, Bacillus sp. strain USML9, and Bacillus sp. strain USMR1 which were isolated from diseased plants harbored the BCA traits and significantly reduced leaf blight severity of rice. Simultaneously, the endophytic BCAs also possessed plant growth promoting traits and were able to enhance rice growth. Application of the selected endophytes (BCAs-PGP) at the early growth stage of rice exhibited potential in suppressing BLB disease and promoting rice growth.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 추계학술대회 및 정기총회
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• pp.25-25
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• 2014

Three species of Fusarium, F. fujikuroi, F. verticillioides and F. proliferatum, are known to be associated with bakanae disease of rice [1, 2]. F. fujikuroi infects rice flowers and survive in endosperm and embryo of the seeds. Infected seed is an important source of primary inoculum of pathogens [3]. Seeds of rice (Oryza sativa cv. Boramchan) collected from bakanae-infected field were found to be 96% infected with Fusarium sp., 52% with F. fujikuroi, 42% with F. verticillioides, and 12% with F. proliferatum as determined by incubation method and species-specific PCR assays. F. fujikuroi was detected at lemma/palea, endosperm and embryo whereas F. verticillioides and F. proliferatum were recovered only from lemma/palea by means of component plating test. Seed disinfection methods have been developed to control bakanae disease and prochloraz has been most widely used for rice seeds. Two chemicals formulated with prochloraz (PC 1) and prochloraz + hexaconazole (PC 2) that inhibit biosynthesis of ergosterol strongly reduced the incidence of Fusarium spp. on selective media to 4.7% and 2.0%, respectively. Disease symptoms of rice seedlings in nursery soil were alleviated by chemical treatment; seedlings with elongated leaves or wide angle between leaf and stem were strikingly reduced from 15.6 to 3.2% (PC 1) and 0 (PC 2), stem rots were reduced from 56.9 to 26.2% (PC 1) and 32.1% (PC 2), and normal seedling increased from 0.4 to 13.3% (PC 2). Prochloraz has some disadvantages and risks such as the occurrence of tolerant pathogens [4] and effects on the sterol synthesis in animals and humans [5]. For these reasons, it is necessary to develop new disinfection method that do not induce fungal tolerance and are safe to humans and animals. Chlorine dioxide ($ClO_2$), that is less toxic, produces no harmful byproducts, and has high oxidizing power, has been reported to be effective at disinfection of several phytopathogenic fungi including Colletotrichum spp. and Alternaria spp. [6]. Gaseous $ClO_2$ applied to rice seeds at a concentration of 20 ppm strongly suppressed mycelial growth of Fusarium fujikuroi, F. verticillioides and F. proliferatum. The incidence of Fusarium spp. in dry seed with 8.7% seed moisture content (SMC) tended to decrease as the concentration of $ClO_2$ increased from 20 to 40 ppm. Applying 40 ppm $ClO_2$ at 90% relative humidity, incidence was reduced to 5.3% and resulted in significant reduction of disease symptoms on MS media. In nursery soil, stem rot was reduced from 56.9 to 15.4% and the number of normal seedlings increased from 0.4 to 25.5%. With water-soaked seeds (33.1% SMC) holding moisture in the endosperm and embryo, the effectiveness of disinfection using $ClO_2$ increased, even when treated with only 20 ppm for four hours. This suggests that moisture was a key element for action of $ClO_2$. Removal of the palea and lemma from seeds significantly decreased the incidence of Fusarium spp. to 3.0%. Seed germination appeared to decrease slightly by water-soaking at $30^{\circ}C$ because of increased SMC and by physical damage of embryos from hulling. These results indicate that the use of gaseous $ClO_2$ was effective as a means to disinfect rice seeds infected with Fusarium spp. and that moisture around the pathogens in the seed was an important factor for the action of $ClO_2$. Further investigations should be conducted to ascertain the best conditions for complete disinfection of Fusarium spp. that infect deep site of rice seeds.

• 원예과학기술지
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• 제29권3호
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• pp.273-277
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• 2011

딸기의 크라운과 뿌리를 갈변시키는 Fusarium oxysporum f. sp. fragariae에 의한 시들음병은 국내 육묘포장에서 발생하는 중요한 토양병해이다. 육묘기 영양번식을 통한 시들음병 전염 유무를 조사하기 위해 '금향' 품종을 대상으로 시들음병에 감염된 모주로부터 일시채묘 방식으로 자묘를 증식하여 시험에 이용하였다. 시들음병 감염묘와 건전묘간의 자묘생산량 비교에서는 접종 58일 후 감염묘의 러너 발생수는 비닐하우스와 인공광 이용형 육묘 모듈에서 각각 2.7개와 3.8개였으나 건전묘에서는 6.5개와 8.4개로 감염묘에 비해 자묘 생산이 2배 이상 되었다. 시들음병에 감염된 모주에서 영양번식을 통한 자묘의 감염율은 정식 58일 후 1차 러너의 상단부위(2-1)에서 100% 검출되었으나 그 이하 부위에서는 검출이 되지 않았다. 정식 90일 후에는 시들음병균이 1차 러너의 상, 중, 하단 부위(2-1, 2-2, 2-3) 모두에서 100% 검출되었으며, 1차 자묘에서도 60%의 검출율을 보였다. 반면 건전 묘에서는 정식 58일과 90일 후에도 시들음병균은 전혀 검출되지 않았다. 위의 결과를 토대로 딸기 시들음병은 토양 전염 외에 감염된 모주로부터 영양번식을 통한 자묘로의 전염 가능성을 확인하였으며 시들음병의 건전묘 생산방법으로 인공광 환경에서 생산된 1차 자묘를 육묘용 모주로 이용하는 것도 좋을 것으로 판단된다.

• 농업과학연구
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• 제12권2호
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• pp.242-252
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• 1985

본(本) 연구(硏究)는 벼 이삭누룩병(病)의 발생생태(發生生態)에 관(關)한 기초자료(基礎資料)를 얻기 위(爲)하여 전투원(專透源)인 균핵(菌核) 및 후막포자(厚膜胞子)의 발아조건(發芽條件)과 병원성(病原性)을 조사(調査)하였으며 발병(發病)에 미치는 재배환경(栽培環境)의 영향(影響)과 수도(水稻) 품종간(品種間)의 발병정도(發病程度)를 조사(調査)하였던 바 그 결과(結果)를 요약(要約)하면 다음과 같다. 1. 이병립(罹病粒)에 형성(形成)되는 후막포자괴(厚膜胞子塊)는 밭벼의 것이 논벼의 것보다 크고 수당(穗當) 이병립수(罹病粒數)도 밭벼에서 많았다. 균핵(菌核)의 형성율(形成率)은 밭벼 22.2%, 논벼 3.6 %로서 밭벼에서 현저(顯著)히 높았다. 2. 월동(越冬) 균핵(菌核)의 발아율(發芽率)은 7월초(月初)의 고온(高溫)에서는 81%로 높았고 발아소요일수(發芽所要日數)도 19일(日)로 짧았으며 균핵(菌核)은 지표면(地表面)이나 지하(地下) 1cm깊이에 매몰(埋沒)된 것은 $25^{\circ}C{\sim}30^{\circ}C$ 고온(溫度)에서 잘 발아(發芽)하였고 균핵(菌核)은 1/4로 절단(切斷)되어도 발아력(發芽力)이 유지(維持)되었다. 3. 자실체(子實體)는 균핵당(菌核當) 평균(平均) 6개(個)가 형성(形成)되었고 자실체당(子實體當) 자낭각(子囊殼)은 50~140개(個)가 형성(形成)되었다. 4. 후막포자(厚膜胞子)는 형성시기(形成初期)인 황색포가(黃色胞子)가 발아력(發芽力)이 왕성(旺盛)하였고 성숙(成熟)해 갈수록 발아율(發芽率)이 저하(低下)되었다. 5. 후막포자(厚膜胞子)는 자낭포자(子囊胞子)는 수잉기(穗孕期) 주사접종(注射接種)에서 발원성(病原性)을 나타냈으며 후막포자(厚膜胞子)의 유아기(幼芽期) 접종(接種)은 병원성(病原性)이 없었다. 6. 이병주(罹病株)의 수당이병립(穗當罹病粒)의 발생수(發生數)는 1~5립(粒)이 대부분(大部分)이었으며 제일하위(第一下位) 지경절(枝梗節)의 벼알에 많이 발생(發生)되었고 상위절(上位節)로 올라갈수록 적었다. 7. 이삭누룩병(病)은 만생종(晩生種)일수록 발병율(發病率)이 높았으며 일반계(一般系) 중(中)에서는 상풍벼, 삼남(三南)벼, 은하(銀河)벼에서 통일계(統一系) 중(中)에서는 풍산, 서광(曙光), 백양(白羊)벼 등(等)에서 발병(發病)이 많았다. 8. 본병(本病)은 질소시비량(窒素施肥量)이 많으면 많을수록 발병(發病)이 많았으며 이앙(移秧)이 늦어질수록 발병(發病)이 많았다. 9. 이삭누룩병(病)의 이병립(罹病粒)이 증가(增加)할수록 수중(穗重), 등숙율(登熟率), 천립중(千粒重) 등(等)이 떨어지고 쌀의 오염도(汚染度)도 높았다. 경제적(經濟的) 피해(被害) 한계선(限界線)은 이병수율(罹病穗率) 0.8%선(線)이었다.

• 생명과학회지
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• 제17권7호통권87호
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• pp.944-947
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• 2007

Bacillus LPO3 (계면활성제와 같이 유화물질을 생산하는)을 hydrocarbon을 감소시키는 bio-control agent로 사용했다. 토양 (시중구입)은 gasoline을 섞어 오염시킨 토양을 사용하였다. 13일 동안 bacteria의 성장, hydrocarbon의 감소, 그리고, Bacillus LP03 의 작물 성장에 미친 요인(식물의 싹과 뿌리의 길이를 포함한)을 관찰하였다. 우리는 이 bacteria의hydrocarbon을 감소 시키는 물질로서 이 균이 생산하는 계면활성제일 것이라는 가능성을 이미 확인 하였으며 이는 식물의 싹과 뿌리의 생장을 촉진하였고, 회색 곰팡이에 대하여항 진균 활성을 보였다. 본 연구에서는 bacteria를 넣지 않은 기름으로 오염된 토양 실험 군에서는 식물이 자라나지 않았을 뿐 아니라 살아남지도 못했다. 실험 결과로 볼 때, gasoline의 hydrocarbon이 시간이 지남에 따라 감소되었고, RNA blotting실험에서는 오염된 토양에서 균의 증식과 더불어 계면활성제관련 유전자 산물의 증가를 확인하였다 결과적으로, 이 bacteria (계면활성제를 생산하는)는 회색 곰팡이에 감염된 토양이나 기름으로 오염된 토양에서 작물이 자랄 수 있게 하기 위한 bio-control agent로서 유효한 균으로 생각된다.

• 한국유기농업학회지
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• 제24권3호
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• pp.427-433
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• 2016

보리누른모자이크병은 토양전염성 곰팡이인 Polymyxa graminis (P. graminis)에 의해 매개된다. 본 연구에서는 BaYMV 이병토양 및 이병주 뿌리로부터 P. graminis의 PCR 검정방법을 확립하였다. P. graminis type I (P. graminis f.sp. temperata) Internal Transcribed Spacer (ITS) 영역의 염기서열 특이적인 primer를 제작하고, 이병토양 및 이병주의 뿌리와 잎으로부터 DNA를 추출하여 PCR 검정을 실시하였다. 결과 P. graminis는 이병토양 및 이병주 뿌리로부터 검출되었다. 남부지역의 대표적인 보리 재배지역 8개 지역으로부터 이병토양을 채집하여 PCR 검정에 의해 P. graminis의 분포상황을 조사하였다. 결과 조사한 지역 전체에서 P. graminis의 분포가 확인되었다.

• Journal of Microbiology and Biotechnology
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• 제20권1호
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• pp.193-201
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• 2010

A specific and rapid real-time PCR assay for detecting Ralstonia solanacearum in horticultural soil and plant tissues was developed in this study. The specific primers RSF/RSR were designed based on the upstream region of the UDP-3-O-acyl-GlcNAc deacetylase gene from R. solanacearum, and a PCR product of 159 bp was amplified specifically from 28 strains of R. solanacearum, which represent all genetically diverse AluI types and all 6 biovars, but not from any other nontarget species. The detection limit of $10^2\;CFU/g$ tomato stem and horticultural soil was achieved in this real-time PCR assay. The high sensitivity and specificity observed with field samples as well as with artificially infected samples suggested that this method might be a useful tool for detection and quantification of R. solanacearum in precise forecast and diagnosis.