• 한국생태학회:학술대회논문집
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• 한국생태학회 2002년도 VIII 세계생태학대회
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• pp.83-91
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• 2002

The Red Queen hypothesis for the advantage of sex predicts that pathogens will evolve by increasing fitness with frequent encounters with specific host genotypes. In this study, BMV population size, measured as an indicator of fitness, was investigated during repeated passages through the same, or different host genotypes of the crop host, Hordeum vulgare (barley). Overall, mean BMV concentration within individual hosts was significantly higher in genetically homogeneous compared to heterogeneous host passage lines. In addition, BMV populations, passaged through a specific host variety, showed higher growth in that host variety compared to BMV passaged through varying varieties. These results supports the Red Queen hypothesis. However, the decrease in viral populations during passages contradicts the Red Queen. Nevertheless, the results found here show that even under simplified conditions, pathogens do not evolve in simple, predictable ways. Constraints on pathogen evolution may lead to counterintuitive results.

• The Korean Journal of Ecology
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• 제25권4호
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• pp.217-225
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• 2002

The Red Queen hypothesis for the advantage of sex predicts that pathogens will evolve by increasing fitness with frequent encounters with specific host genotypes. In this study, BMV population size, measured as an indicator of fitness, was investigated during repeated passages through the same, or different host genotypes of the crop host, Hordeum vulgare (barley). Overall, mean BMV concentration within individual hosts was significantly higher in genetically homogeneous compared to heterogeneous host passage lines. In addition, BMV populations, passaged through a specific host variety, showed higher growth in that host variety compared to BMV passaged through varying varieties. These results supports the Red Queen hypothesis. However, the decrease in viral populations during passages contradicts the Red Queen. Nevertheless, the results found here show that even under simplified conditions, pathogens do not evolve in simple, predictable ways. Constraints on pathogen evolution may lead to counterintuitive results.

• The Plant Pathology Journal
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• 제37권4호
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• pp.404-412
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• 2021

Despite the plant microbiota plays an important role in plant health, little is known about the potential interactions of the flower microbiota with pathogens. In this study, we investigated the microbial community of apple blossoms when infected with Erwinia amylovora. The long-read sequencing technology, which significantly increased the genome sequence resolution, thus enabling the characterization of fire blight-induced changes in the flower microbial community. Each sample showed a unique microbial community at the species level. Pantoea agglomerans and P. allii were the most predominant bacteria in healthy flowers, whereas E. amylovora comprised more than 90% of the microbial population in diseased flowers. Furthermore, gene function analysis revealed that glucose and xylose metabolism were enriched in diseased flowers. Overall, our results showed that the microbiome of apple blossoms is rich in specific bacteria, and the nutritional composition of flowers is important for the incidence and spread of bacterial disease.

• 한국육종학회지
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• 제43권5호
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• pp.383-390
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• 2011

Near-isogenic lines (NILs) carrying bacterial blight resistance genes (Xa4, xa5 and Xa21) were developed in japonica rice using Suweon345 as genetic background. NILs were selected by gene specific DNA markers and inoculation of K1 or K3a race. NILs conferring Xa4 were resistant to K1, K2, K3, and moderately resistant to K3a. NILs conferring xa5 were resistant to K1, K2, K3, and K3a. NILs having Xa21 were susceptible to K1, while resistant to K2, K3 and K3a. Target genes of NILs with the genetic background of Suweon345 were also confirmed by using eleven Philippines races and International Rice Bacterial Blight (IRBB) NILs carrying Xa4, xa5 and Xa21. All NILs had no significant difference from their recurrent parents in the major agronomic traits except for panicle length and brown rice 1,000 grain weight. Heading date of NILs ranged from Aug. 10 to Aug. 11, which was similar to that of recurrent parent, Suweon345. Culm length, number of grains per panicle and ratio of ripened grain of NILs were similar to those of Suweon345. Milled rice of NILs was ranged from 4.82 to 4.93MT/ha. These NILs will be useful for improving resistance to K3a race of bacterial blight pathogens in Korean japonica cultivars.

• 농약과학회지
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• 제7권2호
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• pp.139-148
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• 2003

마늘저장 중 피해실태를 조사하고 경종적 환경적 여러 요인이 마늘 저장 중 부패에 미치는 영향을 구명하여 마늘저장 중 부패를 줄일 수 있는 기술을 개발하기 위하여 수행하였다. 마늘저장 중 피해가 큰 병은 푸른곰팡이병, 마른썩음병 그리고 자주점무늬병(잎마름병) 이었다. 마늘 저장 중 부패는 경종적 요인으로 재배유형 (논, 밭), 연작년수, 수확시기와, 환경요인으로 저장고의 통풍정도, 저장온도 및 습도가 큰 영향을 주는 것으로 나타났다. 마늘은 조기수확할 경우 부패가 심하였고 논재배 마늘보다는 밭재배마늘이 부패가 잘되었다. 그러나 연작년수와 부패율은 무관하였다. 마늘부패에 대한 환경요인의 영향을 조사한 결과, 습도가 증가함에 따라 푸른곰팡이병은 증가하는 것으로 나타났고, 마른썩음병과 잎마름병은 영향을 받지 않았다. 푸른곰팡이병균, 마른썩음병균 및 자주점무늬병균은 $10^{\circ}C$에서 잘 자랐으며, 특히 장기간 (2개월) 배양 할 경우 푸른곰팡이병균 자주점무늬병균은 $-1^{\circ}C$에서 자랐다. 농작업 중 생긴 상처는 마늘부패에 크게 영향을 주는 것으로 나타났다. 병원균을 접종하지 않고 상처를 낼 경우 마늘표면에 상처를 내지 않고 병원균을 접종할 경우보다 부패정도가 더 심하였다. 마늘 저장 부패를 경감하기 위하여, 감자한천배지상에서 세가지 병원균에 대하여 항균성이 높은 7종의 농약을 선발하였다. 이들 농약을 수확전 30일에 살포하고 저장할 경우 tebuconazole과 benomyl/thiram이 부패를 현저히 경감시켰으며, 마늘을 수확한 후 농약현탁액에 침지하여 처리하였을 때 prochloraz, benomyl/thiram, tebuconazole 등이 효과가 우수한 것으로 나타났다. 마늘종구 소독용으로 사용되고 있는 benomyl/thiram을 농가에서 종구용 마늘을 대상으로 분무처리한 경우 방제효과가 매우 우수하였다.

• 한국약용작물학회지
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• 제10권3호
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• pp.155-161
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• 2002

본 연구 결과 2000년 지역적으로 재배적 환경이 다른 수원, 안동, 영주의 백출 재배 포장에서 발생한 이병주들과 토양 시료로부터 SS-배지와 Jee-배지를 이용하여 분리된 균들은 백출 역병의 원인균인 P. drechsleri로 확인되었다. 이들 분리균 들은 격막이 없는 다량의 팽윤균사를 형성하며, 10% V8A 배지에 배양한 경우 PDA배지에 배양한 경우보다 빠른 균생장 속도를 보이며 $5^{\circ}C$이하와 $40^{\circ}C$이상에서는 전혀 균 생장이 이루어지지 않았다. 10% V8A 배지에서 균을 배양한 후 멸균수와 함께 균질화한 균사-유주자 현탁액을 접종원으로 하여 다량의 유묘에 접종한 결과 $5.0%{\sim}26.4%$와 $23.5%{\sim}72.2%$로 다양한 병반율과 이병주율이 확인되어 효과적인 병원성 검정이 이루어 졌다. 안동지역의 토양시료로부터 분리된 P-A200073 균주와 수원지역의 이병주 뿌리로부터 분리된 P-9755가 병원성이 높아 각각 $26.4%{\sim}63.2%$와 $25.1%{\sim}72.2%$의 병반율과 이병주율을 보였으나 무처리구의 경우 이병주가 발생하지 않았다. 접종 이병주의 조직으로부터 균 재 분리를 시도한 결과 대부분의 뿌리와 땅 가줄기에서 P. drechsleri가 분리되었으나 병반을 보이는 상위 줄기와 엽 조직으로부터는 균이 분리되지 않았다.

• Molecules and Cells
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• 제28권2호
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• pp.131-137
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• 2009

Plant defensins are small (5-10 kDa) basic peptides thought to be an important component of the defense pathway against fungal and/or bacterial pathogens. To understand the role of plant defensins in protecting plants against the brown planthopper, a type of insect herbivore, we isolated the Brassica rapa Defensin 1 (BrD1) gene and introduced it into rice (Oryza sativa L.) to produce stable transgenic plants. The BrD1 protein is homologous to other plant defensins and contains both an N-terminal endoplasmic reticulum signal sequence and a defensin domain, which are highly conserved in all plant defensins. Based on a phylogenetic analysis of the defensin domain of various plant defensins, we established that BrD1 belongs to a distinct subgroup of plant defensins. Relative to the wild type, transgenic rices expressing BrD1 exhibit strong resistance to brown planthopper nymphs and female adults. These results suggest that BrD1 exhibits insecticidal activity, and might be useful for developing cereal crop plants resistant to sap-sucking insects, such as the brown planthopper.

• 한국약용작물학회지
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• 제25권1호
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• pp.1-9
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• 2017

Background: Some plants have harmful effects on fungi and bacteria as well as other plants. Incorporating such plant into soil as green manure is effective in reducing population densities of soil pathogens. Methods and Results: Twenty-three species of green manure crops were cultivated after the harvest of 6-year-old ginseng and then incorporated into the soil at the flowering stage. The following year, the root rot ratio of 2-year-old ginseng and soil chemical properties were investigated. In the absence of green manure addition, the $NO_3$ content, electric conductivity (EC), and K content decreased by 95%, 79% and 65%, respectively. In the presence of green manure addition, $P_2O_5$ and $NO_3$ contents reduced by 41% and 25%, respectively. The "survived root ratio" of 2-year-old ginseng significantly increased by 56.2%, 47.5%, and 47.3%, in the Sorghum sudanense, Ricinus communis and Helianthus tuberosus treatment, respectively. In addition, there was a significant increase in the "survived root ratio" in the Secale cereale, Chrysanthemum morifolium, Atractylodes macrocephala, and Smallanthus sonchifolius treatments. The "survived root ratio" of ginseng showed a significant positive correlation with the soil pH and a negative correlation with the $NO_3$ contents, and EC. Conclusions: Cultivation of plant form the Chrysanthemum family as green manure, using mainly the rhizomes was effective for the control of root rot disease of ginseng.

• The Plant Pathology Journal
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• 제29권4호
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• pp.446-450
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• 2013

The ascomycete fungus Fusarium graminearum is a major causal agent for Fusarium head blight in cereals and produces mycotoxins such as trichothecenes and zearalenone. Isolation of the fungal strains from air or cereals can be hampered by various other airborne fungal pathogens and saprophytic fungi. In this study, we developed a selective medium specific to F. graminearum using toxoflavin produced by the bacterial pathogen Burkholderia glumae. F. graminearum was resistant to toxoflavin, while other fungi were sensitive to this toxin. Supplementing toxoflavin into medium enhanced the isolation of F. graminearum from rice grains by suppressing the growth of saprophytic fungal species. In addition, a medium with or without toxoflavin exposed to wheat fields for 1 h had 84% or 25%, respectively, of colonies identified as F. graminearum. This selection medium provides an efficient tool for isolating F. graminearum, and can be adopted by research groups working on genetics and disease forecasting.

• 한국약용작물학회:학술대회논문집
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• 한국약용작물학회 2009년도 심포지엄 및 춘계학술발표회
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• pp.403-404
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• 2009