• 한국미생물·생명공학회지
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• 제46권4호
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• pp.346-359
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• 2018

Xanthomonas oryzae, a bacterial pathogen causing leaf blight disease (BLB) in rice, can cause widespread disease and has caused epidemics globally, resulting in severe crop losses of 50% in Asia. The pathogen is seed-borne and is transmitted through seeds. Thus, control of BLB requires the elimination of the pathogen from seeds. Concern about environment-friendly organic production has spurred improvements in a variety of biological disease control methods, including the use of bacteriophages, against bacterial plant pathogens. The present study explored the potential of bacteriophages isolated from diseased plant leaves and soil samples in killing the bacterial pathogen in rice seeds. Eight different phages were isolated and evaluated for their bacteriolytic activity against different pathogenic X. oryzae strains. Of these, a phage designated ${\varphi}XOF4$ killed all the pathogenic X. oryzae strains and showed the broadest host range. Transmission electron microscopy of ${\varphi}XOF4$ revealed it to be a tailed phage with an icosahedral head. The virus was assigned to the family Siphoviridae, order Caudovirales. Seedlings raised from the seeds treated with $1{\times}10^8pfu/ml$ of ${\varphi}XOF4$ phage displayed reduced incidence of BLB disease and complete bacterial growth inhibition. The findings indicate the potential of the ${\varphi}XOF4$ phage as a potential biological control agent against BLB disease in rice.

• 식물병연구
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• 제18권4호
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• pp.338-348
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• 2012

감자역병은 감자재배에서 가장 중요한 병 중의 하나다. 감자역병의 친환경방제를 위하여 SH-1와 SH-2을 이용하여 감자역병균의 균사생장, 예방효과, 잎을 이용한 생물검정 및 포장시험을 통해 평가하였다. 실내에서 유묘를 이용한 시험에서 SH-1와 SH-2 제형을 살포 후 역병균을 접종 후 예방효과를 조사한 결과 95% 이상 발병을 억제하는 효과가 있었다. SH-1과 SH-2의 균사생장 억제 효과는 $300{\mu}g/ml$의 농도에서 균총의 크기를 74% 이상을 억제하였다. 잎을 이용한 생물검정에서 1% SH-1와 SH-2을 살포 후 1시간 뒤에 병원균을 접종한 결과 병의 발달을 줄였다. 감자 줄기에 총 폴리페놀 함량도 SH-1와 SH-2을 살포한 구에서 증가하였다. 포장에서 역병방제효과 시험에서 1% SH-1와 SH-2을 7일 간격 4회 살포한 처리구에서 각각 72%와 53%의 역병 방제 효과가 있었으며, 14일간 3회 살포한 구에도 유사한 병 방제효과를 보였다. 감자비대기에 1% SH-1와 SH-2 살포는 감자 생체 중을 증가시켰으며, 상품의 비율도 높았다. 이 결과에 의하면 SH-1와 SH-2의 살포는 친환경 유기농업에서 천연살균제로서 역병 방제에 사용 할 수 있으며, 감자 수확량도 증가시킬 수 있다.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 1998년도 Proceedings of International symposium on Recent Technology of Chemical Control of Plant Diseases
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• pp.159-160
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• 1998

• The Plant Pathology Journal
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• 제22권4호
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• pp.375-380
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• 2006

In the survey from 1992 to 2000, twenty-eight parasitic diseases were observed in major apple producing areas in Korea. The predominant apple diseases were white rot(Botryosphaeria dothidea), Marssonina blotch(Marssonina mali), Valsa canker(Valsa ceratosperma), Alternaria leaf spot(Alternaria mali), and bitter rot(Collectotrichum gloeosporioides and C. acutatum). Apple scab that reappeared in 1990 after disappearance for 15 years was disappeared again since 1997. A viroid disease(caused by apple scar skin viroid) was newly found in this survey. The five diseases, fire blight(Erwinia amylovora), black rot(Botryosphaeria obtusa), scab(Cladosporium carpophilum), Monochaetia twig blight(Monochaetia sp.), and brown leaf spot(Hendersonia mali), which had once described in 1928 but no further reports on their occurrence, were not found in this survey. However, blossom blight(Monilinia mali), brown rot(Monilinia fructigena), and pink rot(Trichothecium roseum), which did not occur on apple after mid 1970s, were found in this survey.

• The Plant Pathology Journal
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• 제31권1호
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• pp.78-82
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• 2015

In 2011, a leaf blight disease was observed on cosmos (Cosmos bipinnatus) leaves in Nonsan, Korea. The causal pathogen was isolated and identified based on morphological and molecular approaches. Morphological characteristics of the pathogen matched well with the Alternaria cosmosa and also easily distinguishable from Alternaria zinniae reported from cosmos seeds by producing branched beak. Phylogenetically, the pathogen could not be distinguished from A. passiflorae based on the sequence analysis of a combined data set of Alt a1 and gpd genes. However, A. passiflorae was distinguished from the present species by having conidiophores with 4 to 5 conidiogenous loci. The results indicate that the present Alternaria species is A. cosmosa. Pathogenicity tests revealed that the isolate was pathogenic to the leaves of Cosmos bipinnatus. This is the first report of Alternaria blight disease caused by A. cosmosa on cosmos in Korea.

• 농약과학회지
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• 제6권2호
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• pp.87-95
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• 2002

야외에서 채집한 27종 식물의 메탄올 추출물의 벼 도열병, 벼 잎집무늬마름병, 토마토 잿빛곰팡이병, 토마토 역병, 밀 녹병 및 보리 흰가루병에 대한 방제효과를 실험하였다. 벼 도열병에 대하여는 환삼덩굴, 비비추, 맥문동, 황기 추출물이, 잿빛곰팡이병에 대해서는 닭의장풀 추출물이, 보리 흰가루병에 대하여는 황기 추출물이 그리고 밀 녹병에 대하여는 비비추, 맥문동, 까마중 그리고 황기 추출물이 우수한 방제효과를 보였다. 이들 중 밀 녹병에 대하여 방제효과가 우수한 4종 시료를 선발하여 이들의 방제 특성을 조사하였나. 맥문동과 까마중 추출물은 밀 녹병에 대한 예방효과가 다른 추출물에 비하여 우수하였으며, 치료효과는 황기 추출물은 우수하였으나 까마중 추출물은 다소 미약한 치료활성이 있었다. 식물 추출물의 침투이행성은 엽육이행과 엽간이행으로 실험하였는데, 4종 추출물 모두 엽간이행은 거의 없었으나, 엽육이행은 우수하였다. 식물추출물의 약효지속성은 대부분 좋았으며 특히 비비추와 까마중 추출물은 약제처리 7일 후에도 95% 이상의 방제가를 보였다. 이들 결과를 종합해 보면 4종 식물 추출물 특히 까마중 추출물은 포장에서 밀 녹병에 대하여 우수한 방제효과를 보이리라 생각된다.

• 식물병연구
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• 제25권3호
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• pp.143-148
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• 2019

최근 4년간 경남 남해군 창선면 일대 고사리 재배 포장에서 마름병 증상을 보이는 새로운 병해가 발생하였고 이 병해로 인하여 해당 지역 고사리 생산량이 해마다 크게 감소하고 있다. 2018년 5월, 7월, 10월에 이병 시료를 채취하여 그로부터 총 92개의 곰팡이 균주를 분리하였다. 이들 균주를 건전한 고사리 잎에 접종하여 총 22개 곰팡이 균주가 포장에서 발생된 병징과 동일한 병징을 일으킴이 확인되었다. 이 중 병원성이 가장 높은 2균주를 선발하여 ribosomal RNA, RNA polymerase ${\beta}$-subunit, ${\beta}$-tubulin 유전자 부위, internal transcribed region을 증폭하였다. 해당 증폭 부위의 염기서열을 이용한 계통수 작성을 통해 병원균 균주는 Didymella속의 clade에 속하며, 기존 균주 중 D. rumicicola 또는 D. acetosellae와 비슷하나 기존 종 수준의 subclade에는 포함되지 않았다. 따라서 고사리 마름병을 일으키는 병원균의 정확한 종 동정을 위해 추가적인 분석이 필요하다. 본 결과는 Didymella sp.에 의한 고사리 마름병 발생 첫 보고이다.

• The Plant Pathology Journal
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• 제33권6호
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• pp.543-553
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• 2017

Sesame (Sesamum indicum) is an important oil seed crop of Asia. Yields can be negatively impacted by various factors, including disease, particularly those caused by fungi which create problems in both production and storage. Foliar diseases of sesame such as Alternaria leaf blight may cause significant yield losses, with reductions in plant health and seed quality. The work reported here determined the incidence of Alternaria species infecting sesame seeds grown in the Punjab, Pakistan. A total of 428 Alternaria isolates were obtained from 105 seed samples and grouped into 36 distinct taxonomic groups based on growth pattern and morphological characters. Isolation frequency and relative density of surface sterilized and non-surface sterilized seeds showed that three isolates (A13, A47 and A215) were the most common morphological groups present. These isolates were further identified using sequencing of the Internal Transcribed Spacer (ITS) region of ribosomal DNA (rDNA) and the Alternaria major allergen gene (Alt a 1). Whilst ITS of rDNA did not resolve the isolates into Alternaria species, the Alt a 1 sequences exhibited > 99% homology with Alternaria alternata (KP123850.1) in GenBank accessions. The pathogenicity and virulence of these isolates of Alternaria alternata was confirmed in inoculations of sesame plants resulting in typical symptoms of leaf blight disease. This work confirms the identity of a major source of sesame leaf blight in Pakistan which will aid in formulating effective disease management strategies.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.740-747
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• 2014

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice-growing regions of the world. In spite of their economic importance, there are no effective ways of protecting rice plants from this disease. Bacteriophages infecting Xoo affect the population dynamics of the pathogen and consequently the occurrence of the disease. In this study, we investigated the diversity, host range, and infectivity of Xoo phages, and their use as a bicontrol agent on BLB was tested. Among the 34 phages that were isolated from floodwater in paddy fields, 29 belonged to the Myoviridae family, which suggests that the dominant phage in the ecosystem was Myoviridae. The isolated phages were classified into two groups based on plaque size produced on the lawn of Xoo. In general, there was a negative relationship between plaque size and host range, and interestingly the phages having a narrow host range had low efficiency of infectivity. The deduced protein sequence analysis of htf genes indicated that the gene was not a determinant of host specificity. Although the difference in host range and infectivity depending on morphotype needs to be addressed, the results revealed deeper understanding of the interaction between the phages and Xoo strains in floodwater and damp soil environments. The phage mixtures reduced the occurrence of BLB when they were treated with skim milk. The results indicate that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals.

• 식물병연구
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• 제24권4호
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• pp.265-275
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• 2018

Cashew (Anacardium occidentale L.) is an export crop and source of income in Tanzania. However, its productivity is challenged by insect pests and diseases. Cashew Leaf and Nut Blight Disease (CLNBD) caused by Cryptosporipsis spp. has been cited as one of the most devastating diseases in Tanzania. Studies were conducted to investigate incidences and severities of CLNBD on cashew in farmers' fields and elite cashew hybrids developed in 1996 and 1998 in eastern and southern zones of Tanzania. Furthermore, a screen house experiment was conducted to screen these hybrids against CLNBD at Naliendele Agricultural Research Institute (NARI), Mtwara, Tanzania. The results indicated significant differences (P<0.001) in CLNBD incidences and severities in cashew in farmers' fields across Bagamoyo, Nachingwea and Mtwara districts. Further, there were significant differences (P<0.001) among hybrids in CLNBD severities in the screen house experiment. In ranking the elite cashew hybrids, 38 were tolerant and 14 were susceptible to CLNBD. This observation suggests that elite cashew hybrids developed in 1996 and 1998 are more tolerant to CLNBD compared to cashew found in farmers' fields. These findings strongly suggest that the elite cashew hybrids can be recommended for commercial farming in Tanzania.