• Journal of Microbiology and Biotechnology
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• 제34권3호
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• pp.562-569
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• 2024

Xanthomonas oryzae pv. oryzae (Xoo) causes a devastating bacterial leaf blight in rice. Here, the antimicrobial effects of ᴰ-limonene, ᴸ-limonene, and its oxidative derivative carveol against Xoo were investigated. We revealed that carveol treatment at ≥ 0.1 mM in liquid culture resulted in significant decrease in Xoo growth rate (> 40%) in a concentration-dependent manner, and over 1 mM, no growth was observed. The treatment with ᴰ-limonene and ᴸ-limonene also inhibited the Xoo growth but to a lesser extent compared to carveol. These results were further elaborated with the assays of motility, biofilm formation and xanthomonadin production. The carveol treatment over 1 mM caused no motilities, basal level of biofilm formation (< 10%), and significantly reduced xanthomonadin production. The biofilm formation after the treatment with two limonene isomers was decreased in a concentration-dependent manner, but the degree of the effect was not comparable to carveol. In addition, there was negligible effect on the xanthomonadin production mediated by the treatment of two limonene isomers. Field emission-scanning electron microscope (FE-SEM) unveiled that all three compounds used in this study cause severe ultrastructural morphological changes in Xoo cells, showing shrinking, shriveling, and holes on their surface. Moreover, quantitative real-time PCR revealed that carveol and ᴰ-limonene treatment significantly down-regulated the expression levels of genes involved in virulence and biofilm formation of Xoo, but not with ᴸ-limonene. Together, we suggest that limonenes and carveol will be the candidates of interest in the development of biological pesticides.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 1995년도 Proceedings of special lectures on Molecular Biological Approaches to Plant Disease National Agricultural Science and Technology Institute Suwon, Korea
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• pp.21-25
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• 1995

;Bacterial blight caused by Xanthomonas oryzae pv. Olyzae is one of the most important diseases of rice. Host resistance, which relies on single, dominant resistance genes, is the only reliable method to control the disease at present. Pathogenic variation of the bacteria has been shown to follow the deployment of resistance genes in commercial cultivars. Information on the factors and the mechanisms for genetic variation of this pathogen is limited. Further, we have no clear evidence of whether population variability is due to sexual recombination or to variation introduced by mutations or intragenic recombination in a clonally maintained population.(omitted)itted)

• The Plant Pathology Journal
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• 제24권2호
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• pp.143-151
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• 2008

To define the functions of the rpf genes in Xanthomonas oryzae pv. oryzae (Xoo), which regulates pathogenicity factors in Xanthomonas campestris pv. campestris (Xcc), marker-exchange mutants of each rpf gene were generated. When the mutants were inoculated on a susceptible cultivar, the lesion lengths caused by the rpfB, rpfC, rpfF, and rpfG mutants were significantly smaller than those caused by the wild type, whereas those caused by the rpfA, rpfD, and rpfI mutants were not. Several virulence determinants, including extracellular polysaccharide (EPS) production, xylanase production, and motility, were significantly decreased in the four mutants. However, the cellulase activity in the mutants was unchanged. Complementation of the rpfB and rpfC mutations restored the virulence and the expression of the virulence determinants. Expression analysis of 14 virulence genes revealed that the expression of genes related to EPS production (gumG and gumM), LPS (xanA, xanB, wxoD, and wxoC), phytase (phyA), xylanase (xynB), lipase (lipA), and motility (pitA) were reduced significantly in the mutants rpfB, rpfC, rpfF, and rpfG. In contrast, the expression of genes related to cellulase (eglxob, clsA), cellobiosidase (cbsA), and iron metabolism (fur) was unchanged. The results of this study clearly show that rpfB, rpfC, rpfF, and rpfG are important for the virulence of Xoo KACC10859, and that virulence genes are regulated differently by the Rpfs.

• 한국응용곤충학회지
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• 제23권1호
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• pp.1-6
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• 1984

백엽고병에 대한 저항성품종으로 알려진 밀양 30호의 이병화원인을 구명하기 위하여 수원, 밀양, 해남산에 대한 최고분얼기, 출수기엽과 기본식물에 대한 각균군의 균주별 저항성 관계를 조사한 결과 가. $1979\~'81$년 전국에서 이병된 밀양 30호의 침해균군 비친화성으로 밝혀진 I, II균군의 균주가 다수분리되었다. 나. 산지 및 생육시기별 저항성 정도의 차는 인정할 수 없었으나 II 균군의 특수균주(병원성 분화형)에 대해 침해받았음이 원인이었다. 다. 밀양 30호의 기본식물에서도 동일 균군 균주에 의해 반응이 일치되므로 품종보다 균주의 병원성 분화에 따른 이병화임을 알 수 있었다.

• Journal of Applied Biological Chemistry
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• 제54권4호
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• pp.231-237
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• 2011

A gene encoding a putative alanine racemase in Xanthomonas. oryzae pv. oryzae was cloned, expressed and characterized. Expression of the cloned gene was performed in Escherichia coli BL21(DE3)pLys using a pET-21(a) vector harbouring $6{\times}histidine$ tag. Purification of the recombinant alanine racemase by affinity chromatography resulted in major one band by sodium dodecyl sulfate polyacryl amide gel electrophoresis analysis, showing about 45 kDa of molecular weight. The alanine racemase gene, cloned in this experiment, appears to be constitutively expressed in X. oryzae, as analyzed by reverse transcriptase polymerase chain reaction. The enzyme was the most active toward L-alanine and secondly D-alanine, showing a racemic reaction, thus the enzyme is considered as an alanine racemase. The enzyme was considerably activated by addition of pyridoxal-5-phosphate (PLP), showing that 75% increase in activity was observed at 0.3 mM, compared with control. D-Cysteine as well as L-cysteine significantly inhibited the enzyme activity. The inhibitions by cysteines were more prominent in the absence of PLP, showing 9 and 5% of control activity at 2 mM of addition, respectively. The enzyme was the most active at pH 8.0 and more stable at alkaline pHs than acidic pH condition.

• 한국식물생명공학회:학술대회논문집
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• 한국식물생명공학회 2005년도 추계학술대회 및 한일 식물생명공학 심포지엄
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• pp.152-152
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• 2005

• 한국식물생명공학회:학술대회논문집
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• 한국식물생명공학회 2005년도 추계학술대회 및 한일 식물생명공학 심포지엄
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• pp.153-153
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• 2005

• 한국작물학회:학술대회논문집
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• 한국작물학회 2018년도 추계학술대회
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• pp.225-225
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• 2018

• 한국작물학회:학술대회논문집
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• 한국작물학회 2021년도 추계학술대회
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• pp.221-221
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• 2021

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 춘계학술대회
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• pp.121-121
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• 2022