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Polygenic risk scores (PRSs) have been studied for predicting human diseases, and various methods for PRS calculation have been developed. Most PRS studies to date have focused on European ancestry, and the performance of PRS has not been sufficiently assessed in East Asia. Herein, we evaluated the best-performing PRSs for East Asian populations using data for seven diseases: asthma, breast cancer, coronary artery disease, glaucoma, hyperthyroidism, hypothyroidism, and type 2 diabetes (T2D). A total of 42 PRSs were generated for East Asian samples by applying three PRS methods [linkage disequilibrium (LD) pruning and P-value thresholding (P + T), PRSice, and PRS-CS] and genome-wide association study (GWAS) data from two biobank-scale datasets [European (UK Biobank) and East Asian (BioBank Japan)] to seven diseases. In most cases, PRS-CS showed better predictive performance for disease risk than the other methods and classified low- and high-risk groups more clearly. In addition, the East Asian GWAS data outperformed those from Europeans for T2D PRS, but neither of the two GWAS ancestries showed a dominant effect on PRS performance for other diseases. For East Asian populations, PRS-CS using large-sample GWAS data is likely to provide superior performance, and a PRS generated with GWAS from other ancestries may also perform well.

Erwinia amylovora, a causal bacterium of fire blight disease, is registered as a prohibited quarantine pathogen in Korea. To control the disease, the government should diagnose the disease, dig and bury the host trees when fire blight occurs. Fire blight was the first reported in 43 orchards of Anseong, Cheonan, and Jecheon in 2015, and 42.9 ha of host trees were eradicated. However, the disease spread to eleven cities, so that 348 orchards and 260.4 ha of host trees were eradicated until 2019. Fire blight of Asian pear occurred mainly in the southern part of Gyeonggi, and Chungnam province, on average of 29±9.2 orchards per year. And the age of the infected trees were mostly 20-30 years old. In apple trees, the disease occurred mainly in the northern part of Gyeonggi, Gangwon, and Chungbuk province, on average of 41±57.6 orchards per year, increased highly in 2018 and 2019. The age of infected apple trees were under 20 years old. Therefore, because the disease spread rapidly in young apple trees, spraying control agents to the trees in a timely manner and removing infected trees quickly are important to prevent the spread of fire blight in the orchard of immature trees.

In August 2017, anthracnose symptoms were observed on the petioles and leaf veins of Korean radish (Rhaphanus sativus) in Hongcheon, Jeongseon, and Pyeongchang of the Gangwon province, Korea. Many grayish to dark-brown spots of 1-2 mm in diameter, appeared on the lower surface and leaf veins of the radish leaves. The spots gradually enlarged and coalesced to form dark-brown irregular lesions. Ten Colletotrichum isolates were obtained from the affected tissues of the Korean radish. Out of them, eight isolates were identified as C. higginsianum and two isolates were identified as C. truncatum based on morphological characteristics and multi-l℃us molecular phylogenetic analysis using the internal transcribed spacers and intervening 5.8S rDNA (ITS), partial beta-tubulin gene (TUB2), partial actin gene (ACT), and partial chitin synthase-1 gene (CHS1). The pathogenicity test was carried out on wounded and unwounded Korean radish (cv. Siraegimu and Osarimu), and Chinese cabbage (cv. Chuno and Smart) by in℃ulating with a spore suspension. All isolates except one C. truncatum isolate developed typical symptoms on both wounded and unwounded Korean radish. In Chinese cabbage, only the plants in℃ulated with C. higginsianum isolates developed symptoms regardless of the wound. This is the first report of anthracnose caused by C. truncatum on Korean radish in Korea.

The Ralstonia solanacearum species complex (RSSC) can be divided into four phylotypes, and includes phenotypically diverse bacterial strains that cause bacterial wilt on various host plants. This study used 93 RSSC isolates responsible for potato bacterial wilt in Korea, and investigated their phylogenetic relatedness based on the analysis of phylotype, biovar, and host range. Of the 93 isolates, twenty-two were identified as biovar 2, eight as biovar 3, and sixty-three as biovar 4. Applied to the phylotype scheme, biovar 3 and 4 isolates belonged to phylotype I, and biovar 2 isolates belonged to phylotype IV. This classification was consistent with phylogenetic trees based on 16S rRNA and egl gene sequences, in which biovar 3 and 4 isolates clustered to phylotype I, and biovar 2 isolates clustered to phylotype IV. Korean biovar 2 isolates were distinct from biovar 3 and 4 isolates pathologically as well as genetically - all biovar 2 isolates were nonpathogenic to peppers. Additionally, in host-determining assays, we found uncommon strains among biovar 2 of phylotype IV, which were the tomato-nonpathogenic strains. Since tomatoes are known to be highly susceptible to RSSC, to the best of our knowledge this is the first report of tomato-nonpathogenic potato strains. These results imply the potential prevalence of greater RSSC diversity in terms of host range than would be predicted based on phylogenetic analysis.

Bakanae occurs throughout rice growing regions of the world including Asia, Africa, America and Europe. So far the pathogen causing bakanae on rice has been widely known as F. fujikuroi in the Korean peninsula. However, previous studies have shown that Fusarium species within the Gibberella fujikuroi species complex are commonly associated with bakanae. Therefore the objective of this study is to determine the genetic diversity of the Fusarium species responsible for bakanae. Using morphological approaches and translation of DNA sequences belonging to elongation factor 1 α (TEF), histone H3 and calmodulin genes, the pathogen was identified and characterized. A total 590 isolates of Fusarium species were recovered from the rice plants with typical symptoms of bakanae and rice seeds. Out of one set of the 100 Fusarium isolates, the phylogenetic tree of 90 isolates amplified and constructed from DNA sequences of TEF gene consisted of three main clades. Futher it was observed that of the 89 Fusarium isolates amplified and constructed from 474 bp of DNA sequences of histone H3 gene, consisted of F. fujikuroi and F. proliferatum groups. Lastly, based on DNA sequences of clamodulin gene, 89 isolates including F. fujikuroi and F. proliferatum formed one clade with each reference strain. It could be again sub divided into F. proliferatum group and 2 F. fujikuroi groups. As clearly demonstrated in this study, identifying Fusarium species associated with bakanae only depending on morphological investigation is a highly challenging task, owing to its diverse characteristics. Moreover, other Fusarium species such as F. proliferatum, and F. andiyazi besides F. fujikuroi are also capable of causing bakanae. And also besides these there are other non-pathogenic F. fujikuroi which are hard to distinguish even with molecular identification protocols.

Background Because next-generation sequencing (NGS) for detecting somatic mutations has been adopted in clinical fields, both qualitative and quantitative QC of the somatic variants through whole coding regions detected by NGS is crucial. However, specific applications or guidelines, especially for quantitative QC, are currently insufficient. Our goal was to devise a practical approach for both quantitative and qualitative QC using an example of detecting clonal hematopoiesis of indeterminate potential (CHIP). Methods We applied the QC scheme using commercial reference materials and in-house QC materials (IQCM) composed of haplotype map and cancer cell lines for monitoring CHIP. Results This approach efficiently validated a customized CHIP NGS assay. Accuracy, analytical sensitivity, analytical specificity, qualitative precision (concordance), and limit of detection achieved were 99.87%, 98.53%, 100.00%, 100.00%, and 1.00%, respectively. The quantitative precision analysis also had a higher CV percentage at a lower alternative read depth (R2 = 0.749∼0.858). Use of IQCM ensured more than 100-fold reduction in the cost per run compared with that achieved using commercial reference materials. Conclusion Our approach determined the general analytical performance of NGS for detecting CHIP and recognized limitations such as lower precision at a lower level of variant burden. This approach could also be theoretically expanded to a general NGS assay for detecting somatic variants. Considering the reliable NGS results and cost-effectiveness, we propose the use of IQCM for QC of NGS assays at clinical laboratories.

The soil-borne pathogenic Ralstonia solanacearum species complex (RSSC) is a group of plant pathogens that is economically destructive worldwide and has a broad host range, including various solanaceae plants, banana, ginger, sesame, and clove. Previously, Korean RSSC strains isolated from samples of potato bacterial wilt were grouped into four pathotypes based on virulence tests against potato, tomato, eggplant, and pepper. In this study, we sequenced the genomes of 25 Korean RSSC strains selected based on these pathotypes. The newly sequenced genomes were analyzed to determine the phylogenetic relationships between the strains with average nucleotide identity values, and structurally compared via multiple genome alignment using Mauve software. To identify candidate genes responsible for the host specificity of the pathotypes, functional genome comparisons were conducted by analyzing pan-genome orthologous group (POG) and type III secretion system effectors (T3es). POG analyses revealed that a total of 128 genes were shared only in tomato-non-pathogenic strains, 8 genes in tomato-pathogenic strains, 5 genes in eggplant-non-pathogenic strains, 7 genes in eggplant-pathogenic strains, 1 gene in pepper-non-pathogenic strains, and 34 genes in pepper-pathogenic strains. When we analyzed T3es, three host-specific effectors were predicted: RipS3 (SKWP3) and RipH3 (HLK3) were found only in tomato-pathogenic strains, and RipAC (PopC) were found only in eggplant-pathogenic strains. Overall, we identified host-specific genes and effectors that may be responsible for virulence functions in RSSC in silico. The expected characters of those genes suggest that the host range of RSSC is determined by the comprehensive actions of various virulence factors, including effectors, secretion systems, and metabolic enzymes.

The soil-borne pathogenic Ralstonia solanacearum species complex (RSSC) is a group of plant pathogens that is economically destructive worldwide and has a broad host range, including various solanaceae plants, banana, ginger, sesame, and clove. Previously, Korean RSSC strains isolated from samples of potato bacterial wilt were grouped into four pathotypes based on virulence tests against potato, tomato, eggplant, and pepper. In this study, we sequenced the genomes of 25 Korean RSSC strains selected based on these pathotypes. The newly sequenced genomes were analyzed to determine the phylogenetic relationships between the strains with average nucleotide identity values, and structurally compared via multiple genome alignment using Mauve software. To identify candidate genes responsible for the host specificity of the pathotypes, functional genome comparisons were conducted by analyzing pan-genome orthologous group (POG) and type III secretion system effectors (T3es). POG analyses revealed that a total of 128 genes were shared only in tomato-non-pathogenic strains, 8 genes in tomato-pathogenic strains, 5 genes in eggplant-non-pathogenic strains, 7 genes in eggplant-pathogenic strains, 1 gene in pepper-non-pathogenic strains, and 34 genes in pepper-pathogenic strains. When we analyzed T3es, three host-specific effectors were predicted: RipS3 (SKWP3) and RipH3 (HLK3) were found only in tomato-pathogenic strains, and RipAC (PopC) were found only in eggplant-pathogenic strains. Overall, we identified host-specific genes and effectors that may be responsible for virulence functions in RSSC in silico. The expected characters of those genes suggest that the host range of RSSC is determined by the comprehensive actions of various virulence factors, including effectors, secretion systems, and metabolic enzymes.

Ralstonia solanacearum is the causal agent of the devastating bacterial wilt disease in many high value Solanaceae crops. R. solanacearum secretes around 70 effectors into host cells in order to promote infection. Plants have, however, evolved specialized immune receptors that recognize corresponding effectors and confer qualitative disease resistance. In the model species Arabidopsis thaliana, the paired immune receptors RRS1 (resistance to Ralstonia solanacearum 1) and RPS4 (resistance to Pseudomonas syringae 4) cooperatively recognize the R. solanacearum effector PopP2 in the nuclei of infected cells. PopP2 is an acetyltransferase that binds to and acetylates the RRS1 WRKY DNA-binding domain resulting in reduced RRS1-DNA association thereby activating plant immunity. Here, we surveyed the naturally occurring variation in PopP2 sequence among the R. solanacearum strains isolated from diseased tomato and pepper fields across the Republic of Korea. Our analysis revealed high conservation of popP2 sequence with only three polymorphic alleles present amongst 17 strains. Only one variation (a premature stop codon) caused the loss of RPS4/RRS1-dependent recognition in Arabidopsis. We also found that PopP2 harbors a putative eukaryotic transcriptional repressor motif (ethylene-responsive element binding factor-associated amphiphilic repression or EAR), which is known to be involved in the recruitment of transcriptional co-repressors. Remarkably, mutation of the EAR motif disabled PopP2 avirulence function as measured by the development of hypersensitive response, electrolyte leakage, defense marker gene expression and bacterial growth in Arabidopsis. This lack of recognition was partially but significantly reverted by the C-terminal addition of a synthetic EAR motif. We show that the EAR motif-dependent gain of avirulence correlated with the stability of the PopP2 protein. Furthermore, we demonstrated the requirement of the PopP2 EAR motif for PTI suppression. A yeast two-hybrid screen indicated that PopP2 does not interact with any well-known Arabidopsis transcriptional co-repressors. Overall, this study reveals high conservation of the PopP2 effector in Korean R. solanacearum strains isolated from commercially cultivated tomato and pepper genotypes. Importantly, our data also indicate that the PopP2 conserved repressor motif could contribute to the effector accumulation in plant cells.

2013년 6월, 경기도 여주시에서 저장 중인 고구마 괴근 표면에 갈색의 썩음 증상이 관찰되었다. 병징은 둥글고, 옅은 갈색 내지 진한 갈색이며, 단단하고 건조한 편으로 표피에 한하여 얄팍하게 나타났다. 병반 부위는 오래된 부위에서 움푹 패이고, 괴근의 내부로 깊게 썩히지 않았다. 병든 고구마에서 7개의 Fusarium균을 분리하였고, CLA 배지에서 균학적 특징을 조사한 결과 F. oxysporum으로 동정되었다. 이러한 결과를 확인하기 위하여 elongation factor 1 ${\alpha}$ 유전자 부위의 염기서열을 분석하였다. 그 결과, 7개 균주 중 4개는 F. commune으로, 3개는 F. oxysporum으로 확인되었다. 고구마 괴근을 상처구와 무상처구로 구분하고, 균사절편을 접종하여 병원성을 확인한 결과, 접종 7일 후 F. commune을 접종한 상처구에서만 병징이 관찰되었다. 따라서 본 병을 Fusarium commune에 의한 고구마 표피썩음병으로 명명하며, 국내에서 최초로 보고한다. 【In June 2013, surface rot symptoms were observed on sweet potatoes (Ipomoea batatas) in Yeoju city, Korea. The lesions were circular, light to dark brown, firm, dry, and superficial. The diseased area became sunken in older tissues, and the symptoms usually did not extend deeply into the flesh. Seven isolates of Fusarium species were isolated from diseased sweet potatoes. All isolates were identified as Fusarium oxysporum based on morphological characteristics on CLA medium. To confirm the identification, molecular analysis of elongation factor 1 alpha gene was conducted. Among the isolates, however, four isolates were F. commune, and three isolates were F. oxysporum based on the DNA sequence data. Pathogenicity was tested using agar block inoculation on wounded or unwounded sweet potato pieces. Lesions were observed on wounded sweet potato pieces after 7 days inoculation in only F. commune isolates. This is the first report that F. commune causes Fusarium surface rot of sweet potato in Korea.】

In this study, a whole-cell biotransformation by Bacillus amyloliquefaciens Korean Collection for Type Culture 13588 was carried out to acquire naringenin derivatives. High-performance liquid chromatography analysis of the reaction metabolites showed the presence of 3 different products. The structure of the metabolites was confirmed through high-resolution quadrupole-time-of-flight electrospray-ionization mass spectrometry and nuclear magnetic resonance analysis. The result revealed that B. amyloliquefaciens catalyzes naringenin into 3 derivatives, naringenin 7- O-phosphate, naringenin 7- O-glucoside (prunin), and 6''- O-succinylprunin. To our knowledge, this is the first report of the production of 3 different derivatives when naringenin was used as a substrate. Furthermore, our study also revealed that the product naringenin 7- O-phosphate has approximately 45-fold higher water solubility than that of naringenin. Our finding suggests that biotransformation might solve the low bioavailability of flavonoids.

Institute of Genetic Engineering, Hankyong National University, Ansung 456-749, Korea(Received on October 30, 2013; Revised on November 12, 2013; Accepted on November 19, 2013)Totally sixty three bacteria were isolated from lower stems showing symptoms of bacterial wilt on pepperplants in 14 counties of 7 provinces, Korea. The isolates showed strong pathogenicity on red pepper (cv.Daewang) and tomato (cv. Seogwang) seedlings. All virulent bacteria were identified as Ralstoniasolanacearum based on colony types, physiological and biochemical tests and polymerase chain reaction(PCR). All R. solanacearum isolates from peppers were race 1. The bacterial isolates consisted of biovar 3(27%) and biovar 4 (73%). Based on polymorphic PCR bands generated by repetitive sequence (rep-PCR),the 63 R. solanacearum isolates were divided into 12 groups at 70% similarity level. These results will be usedas basic materials for resistant breeding program and efficient control against bacterial wilt disease of pepper.Keywords : Biovar, Classification, Pepper, Ralstonia solanacearum, Rep-PCR

Sorghum (Sorghum bicolor Moench) was traditionally grown on a small scale, however, at present its cultivation is getting momentum in terms of food and animal feed crop throughtout the Korea. Grain mold symptoms of the plant were frequently observed during disease surveys in Korea from 2007 to 2009. The symptoms were highly variable. Severely infected grain was fully covered with mold and partially infected grain may look normal or discolored. Ninety isolates of Fusarium species were obtained from the diseased plants collected from several locations in the country. Among the collected Fusarium isolates, 41 were identified as Fusarium thapsinum, 23 as F. proliferatum, 12 as F. graminearum, 5 as F. incarnatum, and 3 as F. equiseti based on their morphological and cultural characteristics. Elongation factor 1 alpha gene sequences of the isolates were used for phylogenetic analysis. Analyses of the sequences revealed that the isolates were confirmed to be identical with related species of NCBI GenBank. Pathogenicity tests showed that three dominant species, F. thapsinum, F. proliferatum and F. graminearum were strongly virulent to grains of sorghum. This study is the first report of sorghum grain mold caused by Fusarium species in Korea.

Bacterial diseases in soybean are bacterial pustule by Xanthomonas axonopodis pv. glycines, wildfire by Pseudomonas syringae pv. tabaci, bacterial blight by Pseudomonas savastanoi pv. glycines and bacterial brown spot by Pseudomonas syringae pv. syringae in Korea. It is difficult to identify each disease by early symptoms in fields, because the initial symptoms of these diseases are very similar to each other. In this study, we developed multiplex PCR detection method for rapid and accurate diagnosis of bacterial diseases. The glycinecin A of X. axonopodis pv. glycines, the tabtoxin of P. syringae pv. tabaci, the coronatine of P. savastanoi pv. glycines and the syringopeptin of P. syringae pv. syringae have been reported previously. These bacteriocin or phytotoxin producing genes were targeted to design the specific diagnostic primers. The primer pairs for diagnosis of each bacterial diseases were selected without nonspecific reactions. The studies on simultaneous diagnosis method were also conducted with primarily selected 21 primers. As a result, we selected PCR primer sets for multiplex PCR. Sizes of the amplified PCR products using the multiplex PCR primer set consist of 280, 355, 563 and 815 bp, respectively. This multiplex PCR method provides a efficient, sensitive and rapid tool for the diagnosis of the bacterial diseases in soybean.

C3H4-type RING zinc finger protein (BrRZP1) from Brassica rapa under abiotic stresses. To elucidate the role of the BrRFP1 transcription factor in gene regulation, we transformed tobacco plants with the BrRZFP1 gone. Plants were regenerated from 82 independently transformed callus lines of tobacco and analysed for transgene expression. Trans-gene integration and expression was confirmed by Southern and RT-PCR analyses, respectively. T2 plants displayed more tolerance to the bacterial pathogens Pectobacterium carotovorum and Ralstonia solanacearum, and the tolerance levels were correlated with BrRZFP1 expression levels. These results suggest that the transcription factor BrRZFP1 is an important determinant of stress response in plants and its overexpression in plants could increase biotic stress resistance.

Agricultural Microbiology Division, NAAS, RDA, Suwon 441-707, Korea(Received 12, November 2012., Revised 27, November 2012., Accepted 3, December 2012)ABSTRACT: Stem canker and tuber rot symptoms were observed on yam grown in Andong and Jinju, Koreain 2011. A total of 20 isolates of Rhizoctonia and allied fungi were obtained from the symptomatic plants. Amongthe isolates, 8 isolates were identified as Rhizoctonia solani and 12 isolates as Ceratobasidium sp. based on rDNA-internal transcribed spacer (ITS) sequence similarity. In the cluster analysis of rDNA-ITS sequences, 7 isolates ofR. solani belonged to AG 2-2IIIB and remaining one to AG 1-1A. In addition, among the 12 isolates of Cera-tobasidium sp., 7 isolates belonged to AG-Fa, three isolates to AG-A and the other two isolates to AG-Fb and AG-O, respectively. Pathogenicity tests showed that all the R. solani AG 2-2IIIB isolates are pathogenic on stem andtuber of yam but R. solani AG 1-1A and all the Ceratobasidium isolates are non-pathogenic. The results indicatethat R. solani AG 2-2IIIB is an important pathogen causing stem canker and tuber rot on yams grown in thestudy areas. This is the first report of R. solani AG 2-2IIIB causing stem canker and tuber rot of yam in Korea.KEYWORDS : Rhizoctonia solani, Stem canker, Tuber rot, Yam

In June 2012, leaf spot and stem rot were observed on Wilford Swallowwort plants grown in Cheonan, Korea. Three fungal isolates obtained from the diseased leaves and stems were identified as Stemphylium lycopersici, based on morphological, cultural, and molecular characteristics and pathogenicity. This is the first report of leaf spot and stem rot on Wilford Swallowwort caused by S. lycopersici.

Crop Protection Division, National Academy of Agricultural Science, Rural Development Administration, Suwon 441-707, Korea(Received on February 23, 2012; Revised on August 9, 2012; Accepted on August 10, 2012)In July, 2009, proso millet (Panicum miliaceum), which showing the bacterial brown stripes on leaf sheaths,was collected in Miryang in Korea. Symptoms were systemic brown necrotic stripe lesions on the leaf sheathsand stems, and these symptoms were found in the entire field. The causal agent isolated from symptomaticplants was identified as an Acidovorax avenae subsp. avenae, based on its biochemical and physiologicalcharacteristics and also confirmed by the Biolog data and 16S rRNA gene sequence analysis. Also it causedhypersensitive response (HR) when it was inoculated onto the tobacco and tomato. It caused similarsymptoms when inoculated onto proso millet. This is the first report of A. avenae subsp. avenae, the causalagent of bacterial brown stripe of the proso millet in Korea. Keywords : Acidovorax avenae, Bacterial stripe, Panicum miliaceum기장(Panicum miliaceum L.)은 아프리카, 아시아, 남미에서 널리 이용되는 식량작물로 이들 지역의 단백질 공급에 기여하고 있다(Park 등, 2009). 또한 비타민, 무기질및 식이섬유 등의 기능성 성분의 함량이 높고 다양한 생리활성 물질이 많이 함유되어 있어 건강을 유지시키는 보조식량으로서의 역할이 중요시되고 있다(Ko 등, 2011). Acidovorax avenae subsp. avenae는 1909년 미국 오하이오 지역에서 귀리의 잎마름을 일으키는 식물병원세균으로 Manns(1909)에 의해 처음 보고된 후 벼 세균성줄무늬병(Goto, 1964; Kadota, 1996; Shakya 등, 1985), 옥수수의 세균성 줄기부패병(Rosen, 1926; Summer와 Schaad,1977), 조의 갈색줄무늬병(Rosen, 1926), 사탕수수와 기장의 붉은줄무늬병(Martin과 Wismer, 1989)을 일으키는 것으로 보고되었다. 국내에서는 벼 세균성줄무늬병(Shakya,1980)과 옥수수 줄기썩음병(Lee, 1991)이 보고되어 있으나, 기장에서는 아직 보고된 바 없다.본 연구는 국내에서 기장에 새롭게 발생한 세균성줄무늬병의 병징 및 병원세균의 균학적 특성을 보고하고자 한다.

율무(Coix lacryma-jobi)는 동아시아에 자생하는 작물로, 종실은 주로 건강식품이나 의약용으로 사용되고 있다. 2006년부터 2008년까지 국내 율무 재배 지역에서 이삭마름 증상이 관찰되었다. 병징은 겉껍질이 변색되고, 내부의 속씨는 마르고 쭉정이가 되는 것이다. 159개의 Fusarium균을 분리하였고, 분리 빈도별로 F. graminearum(34%), F. proliferatum(14.5%), F. verticillioides(10.1%), F. equiseti(6.9%), F. fujikuroi(6.3%) 순으로 분리되었고, 그 밖에 F. subglutinans, F. semitectum, F. poae, F. sporodochioides가 분리되었다. 분리균주의 elongation factor 1 alpha 유전자의 염기서열 분석을 통한 계통분석을 수행한 결과, NCBI GenBank에 등록된 균주와 동일한 것을 확인하였다. 분리균주의 병원성 검정을 수행한 결과, F. graminearum, F. proliferatum, F. verticillioides가 병원성이 강하였다. 이 연구는 Fusarium균에 의해 발생한 율무 이삭마름 증상에 대한 첫 번째 보고이다. 【Job's tears (Coix lacryma-jobi) is native to East Asia, and grains of the plant are used as health food and medicinal material. Head blight symptoms of the plant were frequently observed during disease surveys in Korea from 2006 to 2008. The symptoms were characterized as discoloration of husks, and subsequently inside of mature grains were shriveled or emptied. One hundred fifty nine isolates of Fusarium species were obtained from the disease symptoms of the plant collected from several locations in the country. Out of the isolates, the most frequently isolated Fusarium species were F. graminearum (34%), F. proliferatum (14.5%), F. verticillioides (10.1%), F. equiseti (6.9%), and F. fujikuroi (6.3%). Other Fusarium species isolated were F. subglutinans, F. semitectum, F. poae, and F. sporodochioides. Elongation factor 1 alpha gene sequences of the isolates were used for phylogenetic analysis. Analyses of the sequences revealed that the isolates were confirmed to be identical with each reference species of NCBI GenBank. Pathogenicity tests showed that F. graminearum, F. proliferatum and F. verticillioides were strongly virulent to grains of Job's tears. The present study is the first report of head blight of Job's tears caused by Fusarium species in Korea.】

Gray mold symptoms were frequently observed on green twigs, blossoms, leaves, and fruits of blueberry trees grown in greenhouses in Cheongyang, Dangjin, Daejeon, and Jeju during disease survey in eight locations of Korea from 2007 to 2010. The disease symptoms were not observed in the fields of the other locations investigated. The disease incidence ranged 1~30% in the greenhouses investigated. A total of 27 single spore isolates of Botrytis species were obtained from the gray mold symptoms, and all the isolates were identified as Botrytis cinerea based on their morphological and cultural characteristics. Four isolates of the fungus were tested for pathogenicity to leaves of four varieties of blueberry trees by artificial inoculation with conidial suspensions. All the tested isolates caused gray mold symptoms on the leaves, which were similar to those observed in the greenhouses. This is the first report that B. cinerea causes gray mold of blueberry trees grown in greenhouses in Korea.

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice growing regions of the world. There are no effective ways of protecting rice from the disease. In this study, the bacteriophage (phage) mixtures infecting Xoo were investigated as biological control agent on BLB. The effects of pH, heat and ultraviolet on the stability of phages were investigated to check and increase the possibility of practical use in the field. Phages were rather stable between pH 5 and pH 10. The infectivity dropped sharply when the phages were incubated at 50 C and more than 90% of the phages were inactivated after two minutes of ultraviolet treatment. The phages were stable for 7 days at the rice plant leaves, and the phages survived 10 times more than other treatments when mixed with skim milk. Although the skim milk increased the stability of the phages, the control efficacy was not effective. However, the phage mixtures reduced the occurrence of BLB when they were treated with Tecloftalam WP or Acibenzolar-S-methyl simultaneously. The results indicated that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals.

Bakanae disease symptom were observed in barnyard grass in paddy field in Heanam, Jeonnam. The infected plants were blighted and white mass of spore were formed on the stem. Fusarium species were isolated from infected stem and the isolates were identified as Fusarium fujikuroi based on their morphological and molecular characteristics. The isolates of F. fujikuroi were assigned to reference of F. fujikuroi among related Fusarium species based on the translation elongation factor 1-alpha gene sequence. Pathogenicity of the fungal isolates was confirmed on seedlings of rice and barnyard grass by artificial inoculation. The results indicated that barnyard grass can be inoculum source of Bakanae disease on rice. Thus, effective weed management is necessary to Bakanae disease control and healthy seed production.

Colletotrichum panacicola isolates were obtained from anthracnose lesions of Korean ginseng and compared with four Colletotrichum species in morphology, molecular phylogeny and pathogenicity. Based on morphological characteristics, C. panacicola was easily distinguished from Colletotrichum gloeosporioides but not from Colletotrichum higginsianum, Colletotrichum destructivum and Colletotrichum coccodes. A phylogenetic tree generated from ribosomal DNA-internal transcribed spacer sequences revealed that C. panacicola is remarkably distinguished from C. gloeosporioides and C. coccodes but not from C. higginsianum and C. destructivum. However, molecular sequence analysis of three combined genes (actin + elongation factor-1α + glutamine synthatase) provided sufficient variability to distinguish C. panacicola from other Colletotrichum species. Pathogencity tests showed that C. panacicola is pathogenic to Korean ginseng but not to other plants. These results suggest that C. panacicola is an independent taxon distin-zguishable from C. gloeosporioides and other morphologically similar Colletotrichum species.

In order to control postharvest spoilage of satsuma mandarin fruits, rhizobacteria were isolated from soil samples. The Pantoea agglomerans strain 59-4 (Pa 59-4) which suppresses the decay of mandarin fruit by green and blue mold, was tested for the control efficacy and its mode of action was investigated. Pa 59-4 inhibited infection by green and blue mold on wounded mandarins, which were artificially inoculated with a spore suspension of Penicillium digitatum and P. italicum with control efficacies of 85-90% and 75-80%, respectively. The biocontrol efficacy was increased by raising the concentration of cells to between 108 and 109 cfu/ml, and pretreatment with the antagonist prevented subsequent infection by green mold. The population of Pa 59-4 was increased more than 10 fold during the 24 hr incubation at 20oC, indicating that colonization of the wound site might prevent the infection by green mold. Despite poor antifungal activity, the Pa 59-4 isolate completely inhibited the germination and growth of P. digitatum spores at 1 × 108 cfu/ml. We argue that the control efficacy was mediated by nutrient competition. Overall, the effective rhizobacterium, Pa 59-4, was shown to be a promising biocontrol agent for the postharvest spoilage of mandarin fruits by green and blue mold.

A total of 25 isolates of Fusarium fujikuroi were obtained from diseased rice plants in Korea from 2006 to 2007 to assess their resistance against fungicides prochloraz and benomyl + thiram. Minimal inhibitory concentration (MIC) values of F. fujikuroi isolates were examined by agar dilution method. Most of the isolates were sensitive to the fungicides. Out of 25 isolates, six were resistant to prochloraz and three to benomyl + thiram. In addition, the isolates CF245, CF249 and CF337 showed resistant to both fungicides. The progenies ( isolates) obtained through two different crosses between sensitive parental isolates(CF202, CF232 and CF179) and resistant parental isolate (CF337) were evaluated for their mycelial growth at different temperatures and resistance against fungicides. Mycelial growth rate of isolates originated from CF202 CF232 was similar to the parental isolates. However mycelial growth rate of isolates originated from CF179 CF337 was faster than their parent isolates. In case of prochloraz, distribution ratio of sensitivity(S) to resistance(R) against to the fungicide of isolates originated from CF202 CF232 and CF179 CF337 was 86 : 14 and 78 : 22, respectively. In case of benomyl+thiram, all the isolates originated from CF202 CF232 were sensitive to the fungicide, however ratio of sensitivity(S) to resistance(R) against to the fungicide of isolates originated from CF179 CF337 was 35 : 65.

Stem canker symptoms were observed in a rape field in Muan, Korea during a disease survey in May 2006. A total of 15 isolates of Phoma sp. were obtained from the infected stems of the plant. All isolates were identified as Leptosphaeria biglobosa based on their morphological and cultural characteristics. The Korean isolates of L. biglobosa were assigned to `brassicae` among six subclades of L. biglobosa complex based on the entire ITS sequences of rDNA. Pathogenicity of the fungal isolates was confirmed on leaves and stems of rape by artificial inoculation. This is the first report that Leptosphaeria biglobosa causes stem canker of rape in Korea.

The roots of grapevine in the field in which the crown gall was occurred severely in Chungbuk province were collected and Agrobacterium spp. were isolated from the roots using the selective media. The selected 13 isolates were identified as A. tumefaciens with fatty acid analysis using MIDI system, nucleotide sequence of 16S rDNA, biochemical characteristics, and PCR with the species-specific primers. A. vitis, a pathogen of crown gall disease of grapevine was not isolated from the roots. All of the isolates did not show pathogenicity on the tomato seedlings and the stem and root of grapevine. Eric-PCR showed that DNA band patterns of the root isolates were a little more similar to A. tumefaciens than A. vitis. However, overall similarity between the root isolates and the pathogenic strains of A. tumefaciens and A. vitis was low by rep-PCR. These results suggest that a pathogen causing crown gall in grapevine in Chungbuk province may transmitted through the seedlings rather than via soil or roots.

【Biocontrol activity of five strains of selected rhizo-bacteria were tested in tomato against bacterial wilt caused by Ralstonia solanacearum. After root bacterization the plants were grown in a perlite-hydroponic system. Upon challenge inoculation with the pathogen, all of the rhizobacterial strains efficiently suppressed the bacterial wilt in tomato in various rates, at maximum by the strain, Bacillus vallismortis strain EXTN-1. While the percent of infected plants in the non-bacterized control plants were 95%, it was only 65% in plants pre-treated with EXTN-1. It was also demonstrated that the movement of R. solanacearum within the stem was significantly hampered when the plants were root bacterized. As EXTN-1 has no antagonistic properties against R. solanacearum, the bacterial wilt was probably suppressed by a mechanism other than antibiosis. Previously, the strain had been proven to produce an efficient elicitor for inducing systemic resistance in many crops. As the present study confirmed that EXTN-1 has the ability for reducing the pathogen spread in tomato, the strain could be effectively used as a potential biocontrol agent against bacterial wilt.】

To investigate the changes of the resistance to prochloraz of Fusarium species causing bakanae disease, Fusarium isolates were collected from various regions in Korea, and pathogenicity tests were performed using rice seeds. Minimum inhibitory concentration (MIC) and effective concentration of 50% () values of isolates were determined using the agar dilution method. High frequency distribution of MIC values of prochloraz against isolates collected in 2006~2007 and 2013~2014 years were and , respectively. The mean value of isolates increased from in 2006~2007 to in 2013~2014. Based on the value of isolates collected in 2006~2007, the resistant baseline of prochloraz was determined as . Compared with the ratio of resistant isolates in 2006~2007, the ratio of resistant isolates in 2013~2014 increased from 6.5% to 41.6%.

In 2004, average temperature was higher, and rainfall was less than those of previous year, The diseases of rice, barley, pepper, chinese melon, apple and oriental pear were surveyed. Seedling diseases, leaf blast, sheath blight and bacterial blight of rice, phytophthova blight, virus diseases and anthracnose of pepper, and sudden wilt syndrome and powdery mildew of chinese melon grown in plastic greenhouse were severe. Especially, sheath blight and bacterial blight of rice occurred two times higher than those of previous year, Panicle blight of rice decreased about 4 times, compared with the previous year, presumed that the lower rainy days, rainfall and RH suppressed spread of the fungal pathogens to panicles of rice. Lower rainfall during mid- and late Aug caused three-times less occurrence of phytophtora blight of red-pepper than that of the previous year, Another diseases surveyed occurred similar or less than those of the previous year.