• The Plant Pathology Journal
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• 제22권2호
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• pp.119-124
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• 2006

Kudzu vine(Pueraria montana var. lobata) is an invasive climbing woody vine that envelops trees and shrubs, pressing physically and shutting out sunlight, which needs to be controlled. Kudzu vine pathogens were surveyed as a way to seek its biocontrol agents in 2002. Occurrence of a bacterial halo blight disease of kudzu vine was observed at several localities in Korea including Euiwang and Suwon in Gyeonggi Province, Daejon, and Gochang and Buan in Jeonbuk Province. Symptoms of brown to black spots with a surrounding yellowish halo appeared from June and lasted till the rainy season without much expansion, but accompanying often leaf blight and defoliation. Isolated bacteria were identified as Pseudomonas syringae pv. phaseolicola based on physiological and cultural characteristics, Biolog, fatty acid and 16S rDNA sequencing analyses. In artificial inoculation test, these bacteria produced the same halo spot symptoms on kudzu vine and bean plants. They also induced hypersensitive responses (HR) on tobacco, tomato, and chili pepper leaves. This is the first report of a bacterial disease of kudzu vine in Korea, and the bacterial pathogen can be used as a biocontrol agent against the pest plant.

• 식물병연구
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• 제9권4호
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• pp.213-216
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• 2003

2002년 봄, 순천시 비닐 하우스에서 육묘중인 차나무에 세균병이 발견되었다. 초기 병반은 신엽에 작은 수침상 병반이 나타났으며 갈색반점으로 변하였다. 이 병반은 점점 커졌으며, 중륵 또는 엽맥을 따라 신장하였으며 검은색으로 변하였고, 병든 잎은 쉽게 낙엽이 되었다. 병반으로부터 10균주를 분리하여 잎에 접종한 결과 자연 병반과 동일한 병징이 나타났다. 병원세균은 염색반응, 형태적 특성, colony 패턴, 생리적, 생화학적 반응에 따라 Pseudomonas syringae pv. theae로 동정되었다. 국내에서 이 균에 의한 차나무 세균병은 아직 보고되지 않았으므로 병명을 차나무 갈색마름병(brown blight)으로 명명할 것을 제안한다.

• 한국농공학회논문집
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• 제62권4호
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• pp.75-86
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• 2020

The purpose of this study is to develop a technology for estimating rice growth and damage effect according to bacterial leaf blight using UAV multi-spectral imagery. For this purpose, we analyzed the change of aerial images, rice growth factors (plant height, dry weight, LAI) and disease effects according to disease occurrence by using UAV images for 3 rice varieties (Milyang23, Sindongjin-byeo, Saenuri-byeo) from 2017 to 2018. The correlation between vegetation index and rice growth factor during vegetative growth period showed a high value of 0.9 or higher each year. As a result of applying the growth estimation model built in 2017 to 2018, the plant height of Milyang23 showed good error withing 10%. However, it is considered that studies to improve the accuracy of other items are needed. Fixed wing unmanned aerial photographs were also possible to estimate the damage area after 2 to 4 weeks from inoculation. Although sensing data in the multi-spectral (Blue, Green, Red, NIR) band have limitations in early diagnosis of rice disease, for rice varieties such as Milyang23 and Sindongjin-byeo, it was possible to construct the equation of infected leaf area ratio and rice yield estimation using UAV imagery in early and mid-September with high correlation coefficient of 0.8 to 0.9. The results of this study are expected to be useful for farming and policy support related to estimating rice growth, rice plant disease and yield change based on UAV images.

• The Plant Pathology Journal
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• 제24권3호
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• pp.337-351
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• 2008

Host-pathogen interaction in rice bacterial blight pathosystem was analyzed for a better understanding of their relationship and recognition of stable pathogenicity among the populations of Xanthomonas oryzae pv. oryzae. A total number of 52 bacterial strains isolated from diseased leaf samples collected from 12 rice growing states and one Union Territory of India, were inoculated on 16 rice varieties, each possessing known genes for resistance. Analysis of variance revealed that the host genotypes(G) accounted for largest(78.4%) proportion of the total sum of squares(SS), followed by 16.5% due to the pathogen isolates(I) and 5.1% due to the $I{\times}G$ interactions. Application of the Additive Main effects and Multiplicative Interaction(AMMI) model revealed that the first two interaction principal component axes(IPCA) accounted for 66.8% and 21.5% of the interaction SS, respectively. The biplot generated using the isolate and genotypic scores of the first two IPCAs revealed groups of host genotypes and pathogen isolates falling into four sectors. A group of five isolates with high virulence, high absolute IPCA-1 scores, moderate IPCA-2 scores, low AMMI stability index '$D_i$' values and minimal deviations from additive main effects displayed in AMMI biplot as well as response plot, were identified as possessing stable pathogenicity across 16 host genotypes. The largest group of 27 isolates with low virulence, small IPCA-1 as well as IPCA-2 scores, low $D_i$ values and minimal deviations from additive main effect predictions, possessed stable pathogenicity for low virulence. The AMMI analysis and biplot display facilitated in a better understanding of the host-pathogen interaction, adaptability of pathogen isolates to specific host genotypes, identification of isolates showing stable pathogenicity and most discriminating host genotypes, which could be useful in location specific breeding programs aiming at deployment of resistant host genotypes in bacterial blight disease control strategies.

• 식물병연구
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• 제12권2호
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• pp.129-133
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• 2006

2003년 수원의 팥 재배 포장에서 새로운 병해가 발견되었다. 처음에는 잎에서 수침상 점무늬가 형성되고 점점 커져 주위로 노란색의 테두리를 형성하는 진갈색의 반점을 형성한다. 심해지면 잎이 떨어지고 잎자루 및 꼬투리에도 진갈색의 병반이 형성된다. YDC 배지에서 병원세 균을 순수 분리하였을 때 Xanthomonas속 세균의 전형적인 특징인 노란색 색소를 띤 세균이 형성되었다. 분리된 세균을 $10^8 cfu/ml$로 현탁한 후 3 주 동안 자란 팥과 콩에 분무 접종하여 병원성을 확인하였다. 지방산 조성 및 함량과 다양한 탄소원 이용정도를 이용하여 분리세균 SL4311은 X. axonopodis pv. phaseoli로 SL4309와 SL4310 은 X. axonopodis pv. phaseoli var. fuscans로 동정하였으며 이 병을 팥의 세균성잎마름병으로 명명하였다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 추계학술대회
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• pp.73-73
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• 2018

Bacterial leaf blight(BLB), caused by X. oryzae pv. oryzae(Xoo), is one of the most destructive diseases of rice due to its high epidemic potential. Understanding BLB resistance at a genetic level is important to further improve the rice breeding that provides one of the best approaches to control BLB disease. In the present investigation, a collection of 192 accessions was used in the genome-wide association study (GWAS) for BLB resistance loci against four Korean races of Xoo that were represented by the prevailing BLB isolates under Xoo differential system. A total of 192 accessions of rice germplasm were selected on the basis of the bioassay using four isolated races of Xoo such as K1, K2, K3 and K3a. The selected accessions was used to prepare 384-plex genotyping by sequencing (GBS) libraries and Illumina HiSeq 2000 paired- end read was used for GBS sequencing. GWAS was conducted using T ASSEL 5.0. The T ASSEL program uses a mixed linear model (MLM). T he results of the bioassay using a selected set of 192 accessions showed that a large number of accessions (93.75%) were resistant to K1 race, while the least number of accessions (34.37%) resisted K3a race. For races K2 and K3, the resistant germplasm proportion remained between 66.67 to 70.83%. T he genotypic data produced SNP matrix for a total of 293,379 SNPs. After imputation the missing data was removed, which exhibited 34,724 SNPs for association analysis. GWAS results showed strong signals of association at a threshold of [-log10(P-value)] more than5 (K1 and K2) and more than4 (K3 and K3a) for nine of the 39 SNPs, which are plausible candidate loci of resistance genes. T hese SNP loci were positioned on rice chromosome 2, 9, and 11 for K1 and K2 races, whereas on chromosome 4, 6, 11, and 12 for K3 and K3a races. The significant loci detected have also been illustrated, NBS-LRR type disease resistance protein, SNARE domain containing protein, Histone deacetylase 19, NADP-dependent oxidoreductase, and other expressed and unknown proteins. Our results provide a better understanding of the distribution of genetic variation of BLB resistance to Korean pathogen races and breeding of resistant rice.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2019년도 춘계학술대회
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• pp.62-62
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• 2019

Bacterial leaf blight(BLB), caused by X. oryzae pv. oryzae(Xoo), is one of the most destructive diseases of rice due to its high epidemic potential. Understanding BLB resistance at a genetic level is important to further improve the rice breeding that provides one of the best approaches to control BLB disease. In the present investigation, a collection of 192 accessions was used in the genome-wide association study (GWAS) for BLB resistance loci against four Korean races of Xoo that were represented by the prevailing BLB isolates under Xoo differential system. A total of 192 accessions of rice germplasm were selected on the basis of the bioassay using four isolated races of Xoo such as K1 and K2. The selected accessions was used to prepare 384-plex genotyping by sequencing (GBS) libraries and Illumina HiSeq 2000 pairedend read was used for GBS sequencing. GWAS was conducted using TASSEL 5.0. The TASSEL program uses a mixed linear model (MLM). The results of the bioassay using a selected set of 192 accessions showed that a large number of accessions (93.75%) were resistant to K1 race and K2 resistant germplasm proportion remained between 66.67. The genotypic data produced SNP matrix for a total of 293,379 SNPs. After imputation the missing data was removed, which exhibited 34,724 SNPs for association analysis. GWAS results showed strong signals of association at a threshold of [-log10(P-value)] more than 5 (K1 and K2) for nine of the 39 SNPs, which are plausible candidate loci of resistance genes. These SNP loci were positioned on rice chromosome 2, 9, and 11 for K1 and K2 races. The significant loci detected have also been illustrated and make the CPAS markers for NBS-LRR type disease resistance protein, SNARE domain containing protein, Histone deacetylase 19, NADP-dependent oxidoreductase, and other expressed and unknown proteins. Our results provide a better understanding of the distribution of genetic variation of BLB resistance to Korean pathogen races and breeding of resistant rice.

• 식물병연구
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• 제26권4호
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• pp.195-201
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• 2020

Xanthomonas oryzae pv. oryzae는 벼 흰잎마름병을 일으키는 세균이며, 벼 흰잎마름병은 벼 주요 재배지에서 꾸준하게 발생하고 있다. 본 연구에서는 벼흰잎마름병균을 신속하고 간편하게 검출하기 위해 등온증폭법 중 하나인 recombinase polymerase amplification (RPA)를 적용하여 현장진단 등을 위한 유전자기반 진단법을 개발하였다. RPA법은 짧은 시간의 등온 조건에서 유전자 증폭이 가능하다는 장점이 있다. 본 연구에서 개발한 벼 흰잎마름병 RPA 진단법은 39℃에서 5분간만 반응하면 목표유전자의 증폭이 이루어지므로 기존 진단법보다 신속하고 간편하며 우리나라에 존재하는 K1-K3a의 4종 레이스에 모두 적용가능하며, DNA 추출 없이 식물체 잎의 즙액으로 증폭반응 수행이 가능하며 기존 Taq 기반 PCR보다 약 10배 검출 민감도가 높고 고가의 thermal cycler 없이도 항온수조, 발열블록 혹은 체온을 이용한 증폭반응 수행이 가능하다. 벼흰잎마름병은 벼의 농작물재해보험 대상재해 병충해 중의 하나이므로 과학적 진단결과가 요구되나, 일선 농촌지도 현장에서는 유전자기반 진단을 위한 장비, 기술 등의 부족으로 분자진단이 어려웠다. 본 연구에서 개발한 벼 흰잎마름병 RPA 진단을 활용한다 면 병징 의심부위 마쇄액을 주형으로, 손으로 5분 동안 반응시키는 것만으로도 신속하고 간편하게 벼 흰잎마름병의 목표유전자 증폭산물을 형성하므로 벼 흰잎마름병 진단의 최일선에서 활용할 수 있을 것이다.

• 방사선산업학회지
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• 제4권3호
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• pp.209-213
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• 2010

Bacterial blight is one of the most serious diseases of rice (Oryza sativa L.), and it has been known that Xanthomonas oryzae pv. oryzae (Xoo) causes this disease symptom. To develop resistance rice cultivars against Xoo, 3,000 lines of $M_3$ mutants, which were irradiated with gamma ray, were tested by 'scissor-dip method' primarily, and 191 putative resistant lines were selected. In $M_4$ generation, these lines were screened again with various ways such as measuring of symptom of bacterial blight in leaf, number of tiller, fresh weight, and phenotypic segregation ratio in next generation. Finally, six resistance lines were selected. RT-PCR analysis revealed that these lines displayed high level of R-genes such as Xa21, Pi36, and Pi-ta. These results indicate that mutations by gamma ray cause disruptions of regulatory signal transduction systems of these R-genes. Furthermore, these selected mutants could be useful for the development of rice cultivar resistant to Xoo.

• The Plant Pathology Journal
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• 제16권5호
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• pp.286-289
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• 2000

Mechanol extracts of three cold-tolerant eucalyptus trees-Eucalyptus darlympleana, E. gunnii and E. unigera were screened for antimicrobial activity against twenty two phyto-pathogenic fungi and six food-borne bacterial pathogens. E. unigera showed the antagonistic activity against all the tested pathogens. Among the tested fungal pathogens, Pythium species were highly sensitive to the leaf extracts. Especially, P. vanterpoolii, a causal agent of leaf blight in creeping bentgrass (Agrostis palustris), was completely inhibited by the extracts. The eucalyptus extracts were also effective in inhibiting the fungal growth of Botrytis cinerea and Phomopsis sp. isolated from the lesions of kiwifruit soft rot during post-harvest storage. Escherichia coli O-157 was less sensitive to the inhibition than the other bacterial pathogens tested. It was likely that Gram positive bacteria-Bacillus subtilis and Streptococcus mutans were more sensitive to the eucalyptus extracts than Gram negative bacteria-Escherichia coli, Salmonella enteritidis and Pseudomonas aeruginosa. Our findings suggest that the cold-tolerant eucalyptus species have antimicrobial properties that can serve the development of novel fungitoxic agents or food preservatives.