• The Plant Pathology Journal
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• 제22권3호
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• pp.248-254
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• 2006

Pear black necrotic leaf spot (PBNLS) on pear trees (Pyrus pyrifolia) is caused by a Korean isolate of Apple stem grooving virus (ASGV-K). Yellow spots were detected in Phaseolus vulgaris (kidney bean) and Chenopodium quinoa which were grown near the diseased pears in year 2000 through 2003. The ASGV-K, the causative agent of PBNLS, was detected from the symptoms of the diseased kidney bean plant and C. quinoa. ASGV-harboring fungi were also isolated from symptomatic plants and from soils surrounding the infected plants. The ASGV-harboring fungus was identified and characterized as Talaromyces flavus. Ecopathological studies showed that the number of ASGV-harboring fungi on the pear leaves was not correlated with differences in temperature or severity of symptoms. Additionally, there was no difference in fungus frequency among the orchard locations or different host plants. Although the frequency of fungi isolated from the soil was not affected by changes in temperature or location, the fungi occurred at higher densities in the rhizosphere than in the plants themselves.

• The Plant Pathology Journal
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• 제26권2호
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• pp.159-169
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• 2010

Lesion mimic mutant (LMM) plants display spontaneous necrotic lesions on their leaves without any pathogenic infection. Specific rice LMMs designated as spotted leaf (spl) including spl1, spl3, spl4, spl5 and spl6 are genetically known as lesion resembling disease (lrd) mutant. The inheritance patterns in the $F_1$ and $F_2$ progenies of these mutants are controlled by recessive genetic factors. Lesion development in the rice LMMs were controlled by both development stages and environmental factors. The rice LMMs exhibited higher numbers of spots under $45^{\circ}C$ temperature than those under $30^{\circ}C$. Contents of chlorophyll were drastically reduced at 60 days old LMM leaves when the spot formation was severe. The levels of endogenous hydrogen peroxide were highest at 45 days old mutants but reduced at 60 days old. Transcription levels of stress related genes including thioredoxin peroxidase and protein disulfide isomerase were reduced in spotted leaves than those of non spotted leaves. It could be suggested that scavenging system against reactive oxygen species induced by either stresses or innate metabolisms may not work properly in the rice LMMs. As these rice LMMs autonomously expressed clear lesions of lrd phenotype without pathogen infection, it could be useful to understand stresses responses in plants.

• Mycobiology
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• 제48권3호
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• pp.169-183
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• 2020

Nigrospora is a monophyletic genus belonging to Apiosporaceae. Species in this genus are phytopathogenic, endophytic, and saprobic on different hosts. In this study, leaf specimens with disease symptoms were collected from host plants from the Shandong Peninsula, China. The fungal taxa associated with these leaf spots were studied using morphology and phylogeny based on ITS, TEF1, and TUB2 gene regions. In this article, we report on the genus Nigrospora with N. gorlenkoana, N. oryzae, N. osmanthi, N. rubi, and N. sphaerica identified with 13 novel host associations including crops with economic importance such as bamboo and Chinese rose.

• 한국환경농학회지
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• 제14권3호
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• pp.282-288
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• 1995

고추, 들깨, 가지 등 3개 작물에 pH 2.0, 2.7, 3.0 및 6.0(대조구)의 인공산성비를 10mm씩 2일 간격으로 10회 처리한 후 잎의 피해율과 조직의 변화 그리고 효소 활성의 변화를 살펴본 결과를 요약하면 다음과 같다. 1. 산성비 처리로 작물에 나타난 가시적피해는 고추>들깨>가지의 순 이었으며, 작물의 산성비에 대한 일반적인 피해증상은 잎표면에 나타나는 갈색 또는 백색의 반점이다. 2. pH 3.0의 인공산성비를 처리하여 작물의 잎표면을 전자현미경(SEM)으로 관찰한 결과, 가지를 제외한 고추와 들깨 잎표면의 모용(Trichome)이 변형되었다. 3. pH 2.7 인공산성비 처리로 기공(Stoamta)의 피해가 나타났다. 4. 산성비 처리에 따른 작물의 생리적 특성 변화에서 Peroxidase 활성의 차이를 보였으며, 들깨에서는 1회 처리로 급격한 활성증가를 보였다.

• The Plant Pathology Journal
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• 제22권2호
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• pp.155-160
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• 2006

A strain of Pepper mottle virus (PepMov) was isolated from chili pepper plants in Korea. In host range study, this virus, designated PepMoV-SNU1, shared most characteristics with PepMoV isolates reported previously. Thermal inactivation point ($45^{\circ}C\;to\;75^{\circ}C$) and dilution end point ($10^{-1}\;to\;10^{-4}$) of PepMoV-SNU1 showed differences depending on the propagation hosts. Cylindrical and pinwheel-shaped inclusions were always observed in pepper leaf tissues infected with the virus alone. Unexpectedly, a special structure of pinwheel shaped inclusion surrounded with unknown small spots was also observed in the leaf section when co-infected with a strain of pepper mild mottle virus. The partial sequence of coat protein gene and 3' untranslated region of PepMoV-SNU1 showed 98% identity with those of other PepMoV isolates. A primer pair derived from 3' end of the coat protein gene and poly A tail regions were designed. Optimal detection condition of PepMoV-SNU1 by RT-PCR was tested to determine appropriate annealing temperature and additional volumes of oligo-dT (18-mer), dNTP, and Taq polymerase. Under the optimized condition, an expected 500 Up PCR-product was detected in pepper leaves infected with PepMoV-SNU1 but not in healthy plants.

• 한국환경과학회지
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• 제28권8호
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• pp.701-707
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• 2019

Highland farming is agriculture that takes place 400 m above sea level and typically involves both low temperatures and long sunshine hours. Most highland Chinese cabbages are harvested in the Gangwon province. The Ubiquitous Sensor Network (USN) has been deployed to observe Chinese cabbages growth because of the lack of installed weather stations in the highlands. Five representative Chinese cabbage cultivation spots were selected for USN and meteorological data collection between 2015 and 2017. The purpose of this study is to develop a weight prediction model for Chinese cabbages using the meteorological and growth data that were collected one week prior. Both a regression and random forest model were considered for this study, with the regression assumptions being satisfied. The Root Mean Square Error (RMSE) was used to evaluate the predictive performance of the models. The variables influencing the weight of cabbage were the number of cabbage leaves, wind speed, precipitation and soil electrical conductivity in the regression model. In the random forest model, cabbage width, the number of cabbage leaves, soil temperature, precipitation, temperature, soil moisture at a depth of 30 cm, cabbage leaf width, soil electrical conductivity, humidity, and cabbage leaf length were screened. The RMSE of the random forest model was 265.478, a value that was relatively lower than that of the regression model (404.493); this is because the random forest model could explain nonlinearity.

• The Plant Pathology Journal
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• 제38권2호
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• pp.115-130
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• 2022

Though information exists regarding the pathogenesis of the shot-hole disease (SH) in flowering cherry (FC), there has been a lack of research focusing on SH management. Therefore, here, we investigated the inhibitory activities of antagonistic bacteria against SH pathogens both in vitro and in vivo as well as their biochemical characteristics and bioactive compounds. Two biosurfactant-producing bacterial antagonists, identified as Bacillus velezensis strains JCK-1618 and JCK-1696, exhibited the best effects against the growth of both bacterial and fungal SH pathogens in vitro through their cell-free culture filtrates (CFCFs). These two strains also strongly inhibited the growth of the pathogens via the action of their antimicrobial diffusible compounds and antimicrobial volatile organic compounds (VOCs). Crude enzymes, solvent extracts, and biosurfactants of the two strains exhibited antimicrobial activities. Liquid chromatography/electrospray ionization time-of-flight mass spectrometric analysis of the partially purified active fractions revealed that the two antagonists produced three cyclic lipopeptides, including iturin A, fengycin A, and surfactin, and a polyketide, oxydifficidin. In a detached leaf assay, pre-treatment and co-treatment of FC leaves with the CFCFs led to a large reduction in the severity of the leaf spots caused by Epicoccum tobaicum and Bukholderia contaminans, respectively. In addition, the two antagonists produced indole-3-acetic acid, siderophore, and a series of hydrolytic enzymes, along with the formation of a substantial biofilm. To our knowledge, this is the first report of the antimicrobial activities of the diffusible compounds and VOCs of B. velezensis against the SH pathogens and their efficiency in the biocontrol of SH.

• 식물병연구
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• 제25권2호
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• pp.79-83
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• 2019

제주에서 재배되는 백합에서의 바이러스 발생률 및 발병현황을 조사하기 위해 2015~2018년까지 시료를 채집하여 RT-PCR로 바이러스 감염양상을 조사하였다. 수집된 시료에 조사된 바이러스는 LSV 감염비율이 69.7%, PIAMV 46.8%, LMoV 38.3%, CMV 17.1% 순으로 발생하였으며, 바이러스 감염형태는 복합감염이 70.0%, 단독감염이 17.9%로 대부분 복합감염의 형태로 발병됨을 알 수 있었다. 복합감염의 발생률은 2015년 PlAMV와 LSV의 2종 복합감염이 76.7%로 가장 많이 발생하였으며, 2016년은 PlAMV, LSV와 LMoV의 3종 복합감염 25.9%, 2017년에는 LSV, LMoV와 CMV의 3종 복합감염이 14.9%로 발생되었으며, 2018년 PlAMV, LSV와 LMoV의 3종 복합감염 11.8%가 발생하는 것으로 나타났다. 전체적으로 제주지역의 발생하는 주요 바이러스는 LSV와 PlAMV를 포함한 복합감염이 가장 많은 것으로 나타났으며, 2종~4종 복합감염도 대부분 LSV와 PlAMV를 포함한 복합감염에 LMoV와 CMV가 결합한 형태를 보였으며, 이와 같은 결과를 종합해 볼 때 조사기간 4년 동안 지속적으로 발생하는 LSV와 PlAMV 복합감염의 양상은 제주지역 백합에 피해를 발생시키는 중요한 감염형태인 것으로 확인할 수 있었다. 2013년 PlAMV 최초 발생으로 긴급 공적방제 후 PIAMV 발생률은 2015년 82.0%, 2016년 49.4%, 2016년 13.6%, 2018년에는 39.5%로 PlAMV는 매년 발생하는 양상을 보였다. LSV 단독감염시에는 병징이 나타나지 않았으나 복합감염시에는 LSV와 LMoV가 함께 감염되면 모자이크와 잎의 malformation증상이 함께 나타났다. LSV, CMV 및 LMoV의 3종 복합감염 시 엷은 갈색빛의 괴저 반점이 나타났으며, 모자이크와 leaf curling이 유발되었다. PIAMV는 단독감염보다 복합감염이 많았으며, 복합감염의 증상으로는 적갈색의 퇴록반점 발생 후 괴사로의 진전, 심한 모자이크 및 잎 기형, 축엽 등 백합의 상품성을 크게 떨어뜨리고, 복합감염일 때 병징이 더욱 심하게 나타났다.

• The Plant Pathology Journal
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• 제33권1호
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• pp.9-20
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• 2017

Incidence of leaf blast on nursery plants and pitting disease on maturing banana bunches has been recorded in banana plantations during rainy season in Eastern India during 2014 to 2015. Taxonomical identification as well as DNA sequence analysis of the internal transcribed spacer region of fungus isolated from affected tissue culture derived plantlets and fruits confirmed the pathogen to be Pyricularia angulata Hashioka "in both the cases". Koch's postulates were proved on young plantlets as well as on maturing fruits of cv. Grand Naine under simulated conditions. Evolutionary history was inferred and presented for our P. angulata strain PG9001 with GenBank accession no. KU984740. The analysis indicated that the P. angulata is phylogenitically distinct from other related species related to both Pyricularia and Magnaporthe. Detailed symptoms of blast lesions on young leaves, transition leaves, mid rib, petioles, peduncle, maturing bunches, bunch stalks and cushions were documented. Notably, the distinct small pitting spots on maturing bunches reduced the visual appeal of mature fruits. Appearance of pitting symptoms on fruits in relation with age of fruits and their distribution pattern on bunch and fingers was also documented in detail. Further, the roles of transitory leaves, weed hosts, seasonality on disease occurrence have also been documented.

• Mycobiology
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• 제46권2호
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• pp.172-176
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• 2018

A new species belonging to the genus Alternaria was isolated from the necrotic leaf spots of Brassica rapa subsp. pekinensis in Yuseong district, Daejeon, Korea. It is an occasional isolate, not an etiological agent, which is morphologically similar to A. broccoli-italicae, but differs in conidial size and conidiophore shape. Phylogenetic analysis using the sequence datasets of the internal transcribed spacer (ITS) region of the rDNA, glyceraldehyde-3-phosphate dehydrogenase (gpd), and plasma membrane ATPase genes showed that it is distantly related to A. broccoli-italicae and closely related to Alternaria species in the section Pseudoalternaria, which belonged to a clade basal to the section Infectoriae. Morphologically, the species is unique because it produces solitary conidia or conidial chains (two units), unlike the four members in the section Pseudoalternaria that produce conidia as short branched chains. It exhibits weak pathogenicity in the host plant. This report includes the description and illustration of A. brassicifolii as a new species.