• 한국유기농업학회지
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• 제14권2호
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• pp.179-189
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• 2006

재식거리에 따른 옥수수의 광합성율의 차이를 보면, 이식 후 23일째(5월 31일)에 재식거리 $40{\times}40cm$에서 제일 낮게 나타났으나, 시일이 지나면서 식물체의 내염성 증가로 광합성율이 큰 차이는 보이지 않았다. 식물체의 생육특성의 차이를 보면, 이식 후 23일째(5월 31일)에 염류의 영향으로 재식거리 $40{\times}40cm$에서 생육저해가 나타났지만, 시일이 지나면서 왕성한 생장을 보였다. 식물체내의 염분함량의 차이를 보면, 대체로 재식거리 $40{\times}40cm$에서 다른 재식거리보다 높은 경향을 보였으며, 염류흡수 차이를 보면 $K^{+}$ 함량이 다른 염류함량보다 훨씬 높게 나타났다. 옥수수의 재배에 따른 토양의 제염효과를 보면, 재식거리 $30{\times}30cm$에서 $K^{+}$는 28%, $Ca^{2+}$는 36.6%, $Mg^{2+}$는 30.6%, $Na^{+}$는 22.9%로 이식 후 37일째(6월 14일)에서 이식 후 23일째(5월 31)에 비해 현저하게 감소하였다. 또한 표토의 염류함량이 심토보다 높게 나타났다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.238-238
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• 2017

Salt stress is one of the deteriorating abiotic stresses due to the climate change, which causes over-accumulation of $Na^+$ and $Cl^-$ ions in plants and inhibits the growth and yield of rice especially in coastal Southeastern Asia. The yield components of rice plant (panicle number, spikelet number per panicle, 1000-grain weight, % of ripened grains) that are majorly affected by salt stress vary with growth stages at which the plant is subjected to the stress. In addition, the salt sensitivity of each yield component differs among rice varieties even when the salt-affected growth stage was same, which indicates that the physiological mechanism to maintain each yield component is different from each other. Therefore, we hypothesized that rice plant has different genes/QTLs that contribute to the maintenance of each yield component. Using a Japanese leading rice cultivar, Koshihikari, and salt-tolerant Nona bokra's chromosome segment substitution lines (CSSLs) with the genetic background of Koshihikari (44 lines in total) (Takai et al. 2007), we screened higher yielding CSSLs under salinity in comparison to Koshihikari and identified the yield components that were improved by the introgression of chromosome segment(s) of Nona bokra. The experiment was conducted in a salinized paddy field. One-month-old seedlings were transplanted into a paddy field without salinity. These were allowed to establish for one month, and then the field was salinized by introducing saline water to maintain the surface water at 0.4% salinity until harvest. The experiments were done twice in 2015 and 2016. Although all the CSSLs and Koshihikari decreased their yield under salinity, some CSSLs showed relatively higher yield compared with Koshihikari. In Koshihikari, all the yield components except panicle number were decreased by salinity and % of ripened grains was mostly reduced, followed by spikelet number per panicle and 1000-grain weight. When compared with Koshihikari, keeping a higher % of ripened grains under salinity attributed to the significantly greater yield in one CSSL. This indicated that the % of ripened grains is the most sensitive to salt stress among the yield components of Koshihikari and that the Nona bokra chromosome segments that maintained it contributed to increased yield under salt stress. In addition, growth analyses showed that maintaining relative growth rate in the late grain filling stage led to the increased yield under salt stress but not in earlier stages.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.20-20
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• 2017

Plant genomes include heterochromatic loci that consist of repetitive sequences and transposable elements. LTR retrotransposon is the major class of transposons in advanced plants in terms of proportion in plant genome. The elements contribute not only to genome size but also to genome stability and gene expression. A number of cases have been reported transposon insertions near genic regions affect crop traits such as fruit pigments, stress tolerance, and yields. Functional LTR retrotransposons produce extrachromosomal DNA from genomic RNA by reverse transcription that takes place within virus-like-particles (VLPs). DECREASED DNA METHYLATION 1 (DDM1) plays important roles in maintaining DNA methylation of heterochromatin affecting all sequence contexts, CG, CHG, and CHH. Previous studies showed that ddm1 mutant exhibits massive transcription of retrotransposons in Arabidopsis, but only few of them were able to create new insertions into the genome. RNA-dependent RNA POLYMERASE 6 (RDR6) is known to function in restricting accumulation of transposon RNA by processing the transcripts into 21-22 nt epigenetically activated small interfering RNA (easiRNA). We purified VLPs and sequence cDNA to identify functional LTR retrotransposons in Arabidopsis ddm1 and ddm1rdr6 plants. Over 20 LTR copia and gypsy families were detected in ddm1 and ddm1rdr6 sequencing libraries and most of them were not reported for mobility. In ddm1rdr6, short fragments of ATHILA gypsy elements were detected. It suggests easiRNAs might regulate reverse transcription steps. The highest enriched element among transposon loci was previously characterized EVADE element. It has been reported that active EVADE element is more efficiently silenced through female germline than male germline. By genetic analyses, we found ddm1 and rdr6 mutation affect maternal silencing of active EVADE elements. DDM1-GFP protein accumulated in megaspore mother cell but was not found in mature egg cell. The fusion protein was also found in early embryo and maternal DDM1-GFP allele was more dominantly expressed in the embryo. We observed localization of DDM1-GFP in Arabidopsis and DDM1-YFP in maize and found the proteins accumulated in dividing zone of root tips. Currently we are looking at cell cycle dependency of DDM1 expression using maize system. Among 10 AGO proteins in Arabidopsis, AGO9 is specifically expressed in egg cell and shoot meristematic cells. In addition, mutation of AGO9 and RDR6 caused failure in maternal silencing, implying 21-22 nt easiRNA pathway is important for retrotransposon silencing in female gametophyte or/and early embryo. On the other hand, canonical 24 nt sRNA-directed DNA methylation (RdDM) pathways did not contribute to maternal silencing as confirmed by this study. Heat-activated LTR retrotransposon, ONSEN, was not silenced by DDM1 but the silencing mechanisms require RdDM pathways in somatic cells. We will propose distinct mechanisms of LTR retrotransposons in germline and somatic stages.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.97-97
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• 2017

Plant genomes include heterochromatic loci that consist of repetitive sequences and transposable elements. LTR retrotransposon is the major class of transposons in advanced plants in terms of proportion in plant genome. The elements contribute not only to genome size but also to genome stability and gene expression. A number of cases have been reported transposon insertions near genic regions affect crop traits such as fruit pigments, stress tolerance, and yields. Functional LTR retrotransposons produce extrachromosomal DNA from genomic RNA by reverse transcription that takes place within virus-like-particles (VLPs). DECREASED DNA METHYLATION 1 (DDM1) plays important roles in maintaining DNA methylation of heterochromatin affecting all sequence contexts, CG, CHG, and CHH. Previous studies showed that ddm1 mutant exhibits massive transcription of retrotransposons in Arabidopsis, but only few of them were able to create new insertions into the genome. RNA-dependent RNA POLYMERASE 6 (RDR6) is known to function in restricting accumulation of transposon RNA by processing the transcripts into 21-22 nt epigenetically activated small interfering RNA (easiRNA). We purified VLPs and sequence cDNA to identify functional LTR retrotransposons in Arabidopsis ddm1 and ddm1rdr6 plants. Over 20 LTR copia and gypsy families were detected in ddm1 and ddm1rdr6 sequencing libraries and most of them were not reported for mobility. In ddm1rdr6, short fragments of ATHILA gypsy elements were detected. It suggests easiRNAs might regulate reverse transcription steps. The highest enriched element among transposon loci was previously characterized EVADE element. It has been reported that active EVADE element is more efficiently silenced through female germline than male germline. By genetic analyses, we found ddm1 and rdr6 mutation affect maternal silencing of active EVADE elements. DDM1-GFP protein accumulated in megaspore mother cell but was not found in mature egg cell. The fusion protein was also found in early embryo and maternal DDM1-GFP allele was more dominantly expressed in the embryo. We observed localization of DDM1-GFP in Arabidopsis and DDM1-YFP in maize and found the proteins accumulated in dividing zone of root tips. Currently we are looking at cell cycle dependency of DDM1 expression using maize system. Among 10 AGO proteins in Arabidopsis, AGO9 is specifically expressed in egg cell and shoot meristematic cells. In addition, mutation of AGO9 and RDR6 caused failure in maternal silencing, implying 21-22 nt easiRNA pathway is important for retrotransposon silencing in female gametophyte or/and early embryo. On the other hand, canonical 24 nt sRNA-directed DNA methylation (RdDM) pathways did not contribute to maternal silencing as confirmed by this study. Heat-activated LTR retrotransposon, ONSEN, was not silenced by DDM1 but the silencing mechanisms require RdDM pathways in somatic cells. We will propose distinct mechanisms of LTR retrotransposons in germline and somatic stages.

• 한국환경농학회지
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• 제33권3호
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• pp.220-230
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• 2014

BACKGROUND: Excessive metals in the soil have become one of the most significant environmental problems. Phytoremediation has received considerable attention as a method for restoring the contaminated soils. The microbes having remarkable metal tolerance and plant growth-promoting abilities could also play a significant role in remediation of metal-contaminated soils, because bioaugmentation with such microbes could promote phytoextraction of metals. Therefore, the present study was focused on evaluating the phytoextraction of heavy metals (Co, Pb and Zn) in Helianthus annuus (sunflower) induced by bioaugmentation of a phosphate solubilizing bacterium. METHODS AND RESULTS: A phosphate solubilizing bacterium was isolated from metal-contaminated soils based on the greater halo size (>3 mm) with solid NBRIP agar medium containing 10 g glucose, 5 g $Ca_3(PO_4)_2$, 5 g $MgCl_2{\cdot}6H_2O$, 0.25 g $MgSO_4.7H_2O$, 0.2 g KCl, 0.1 g $(NH_4)_2SO_4$ in 1 L distilled water. Isolated bacterial strain was assessed for their resistance to heavy metals; $CoCl_2.6H_2O$, $2PbCO_3.Pb(OH)_2$, and $ZnCl_2$ at various concentrations ranging from $100-400{\mu}g/mL$ (Co, Pb and Zn) using the agar dilution method. A pot experiment was conducted with aqueous solutions of different heavy metals (Co, Pb and Zn) to assess the effect of bacterial strain on growth and metal uptake by Helianthus annuus (sunflower). The impact of bacterial inoculation on the mobility of metals in soil was investigated under laboratory conditions with 50 mL scaled polypropylene centrifuge tubes. The metal contents in the filtrate of plant extracts were determined using an atomic absorption spectrophotometer (Perkinelmer, Aanalyst 800, USA). CONCLUSION: Inoculation with Enterobacter ludwigii PSB 28 resulted in increased shoot and root biomass and enhanced accumulation of Co, Pb and Zn in Helianthus annuus plants. The strain was found to be capable of promoting metal translocation from the roots to the shoots of H. annuus. Therefore, Enterobacter ludwigii PSB 28 could be identified as an effective promoter of phytoextraction of Co, Pb and Zn from metal-contaminated soils.

• Journal of Plant Biotechnology
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• 제38권1호
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• pp.54-61
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• 2011

에틸렌 생합성 효소인 ACC oxidase 유전자인 CAO cDNA가 antisense 방향으로 도입된 형질전환 담배 식물체는 endogenous한 NtACO의 발현 및 에틸렌 생합성이 모두 억제되었다. 또한 폴리아민 생합성 효소인 SAMDC의 유전자 발현 및 효소 활성이 증가하였고 spermidine 함량이 증가하였다. 이러한 결과는 에틸렌 생합성의 감소로 인하여 세포 내 폴리아민 함량의 변화가 유도되는 경쟁적 관계로 spermidine이 증가하였고 이것은 SAMDC의 발현 및 활성 증가를 유도하였다고 여겨진다. 또한 이들 형질전환 식물체는 담배 역병균에 대한 저항 효과 뿐만 아니라 PR 단백질의 유전자들의 발현양이 증가하였는데 이는 에틸렌 감소에 유도되는 폴리아민 중에서도 spermidine의 증가가 PR 단백질의 유전자들의 발현을 촉진시키고 그 결과 병원균 감염에 대한 저항성을 유도하는 기작이 작동한 것으로 여겨진다. Spermidine을 합성하는데 중요하게 작용하는 SAMDC의 활성을 억제하는 MGBG를 처리한 경우에는 PR1a 발현이 억제된 경우에서 이 기작의 가능성을 확인하였다. 결론적으로 병원균 감염에 대한 과정에서 spermidine의 생합성이 증가하게 되면 PR 단백질 등 스트레스 저항성 관련 단백질들이 유도되어 스트레스 저항성을 높일 수 있을 것으로 사료된다.

• Journal of Plant Biotechnology
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• 제38권1호
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• pp.22-29
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• 2011

비생물학적 스트레스로 $H_2O_2$를 이용하여 산화적 스트레스와 고염분 스트레스를 처리한 후 ROS의 생성을 확인한 결과 스트레스 처리 후 30분에 일시적으로 1차 peak를 형성하였다가 거의 basal level까지 감소하고 다시 증가하여 3시간에 매우 다량의 2차 peak를 형성한 후 거의 basal level로 다시 낮아지는 biphasic 양상을 나타내게 된다. 따라서 ROS의 생성은 초기 30분 내에 일시적으로 발생한 Phase I의 ROS와 Phase II의 좀 더 장기적으로 다량의 고농도로 발생된 ROS의 생리적 역할이 다를 것으로 여겨진다. 본 논문에서는 스트레스 처리 시 생성되는 ROS를 확인한 후 ROS 생성 유전자인 RbohD와 RbohF 유전자 발현이 억제된 RbohD-AS, RbohF-AS 형질전환 식물체를 이용하여 실험을 수행하였다. 스트레스에 의해 생성되는 ROS의 생성을 억제시킴으로써 스트레스에 대한 ethylene 생성이 더 적은 것으로 나타났다. 또한, 이들 형질전환 식물체에서 ethylene 생성과 $H_2O_2$ 억제 효과를 확인하였으며 고염분 등의 스트레스에 대한 저항성은 ROS와 ethylene의 생성이 저하되어 나타난 것으로 판단된다. 산화적 스트레스와 고염분 스트레스에서 후기 ethylene이 다량으로 생성되는 시기, 즉 세포손상이 초래되는 후기에서 DNA fragmentation 분석을 통해서 ROS와 ethylene의 생성이 높은 식물체일수록 PCD가 높게 나타난 것으로 여겨지며, 이 과정에서 작용하는 유전자는 RbohD와 RbohF인 것으로 보이며, RbohD가 더 효과적으로 작용하는 것으로 생각된다. 따라서 스트레스에 반응하는 신호전달과정에서 초기에 ROS가 생성이 되고 후기에 ethylene이 다량으로 생성되어 결국 세포죽음에 이르게 하는 상호 synergism을 일으켜 반응을 나타내며, 이러한 반응 과정에서 RbohD와 RbohF 유전자 발현의 억제가 스트레스에 대한 식물체의 저항성을 높이는 것으로 사료된다.

• Applied Biological Chemistry
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• 제25권3호
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• pp.135-141
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• 1982

Pot에 재배(栽培)한 수도(水稻) 진주벼와 이리 348호(號)에 수분 결핍과 염장애를 유도한 다음 몇가지 유기대사산물(有機代謝産物)과 무기(無機)이온의 함량(含量)을 측정(測定)하고 관계되는 몇가지 효소활성(酵素活性)을 측정(測定)하여 비교검토(比較檢討)하였다. 비내염성(非耐鹽性)으로 알려진 이리 348호(號)가 부적환경조건(不適環境條件)에서 수분손실(水分損失)이 심하고 proline의 함량(含量)도 많았다. 2품종(品種) 모두 부적환경조건(不適環境條件)에서 조단백질, 총유리아미노산, proline, polypheonol화합물(化合物)이 증가(增加)됐으나 환원량(環元糧)은 수분장애구(水分障碍區)에서만 축적(蓄積)되었다. 조단백질에 대한 유기용질(有機溶質)의 비(比)는 진주벼의 부적환경구(不適環境區)에서만 증가한 반면 이리 348호(號)에서는 변화가 없었다. 부적환경구(不適環境區)에서 황성(活性)이 증가(增加)한 효소(酵素)로는 protease, ${\alpha}-amylase$, phosphorylase가 있으며, 특히 조단백질에 대한 총유리아미노산의 비(比)의 증가(增加)는 protease에 의한 단백질의 가수분해(加水分解)에 기인했다. $Na^+$과 $Cl^-$의 함량은 이리 348호(號)에서 진주벼에서 보다 높았다. $Na^+/Ca^{2+}$과 양이온의 일가(一價)/이가(二價)의 값들은 진주벼에서 항상 낮았고, $K^+/Na^+$은 진주벼에서 높았다. 그러므로 이러한 값이 염해(鹽害)와 한발(旱魃)에 대한 저항성과 어떠한 상관(相關)이 있는지 더욱 연구(硏究)할 필요가 있다고 본다.

• Journal of Acupuncture Research
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• 제23권2호
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• pp.1-19
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• 2006

Objectives : The aim of this study was to investigate the hypoglycemic and hypolipidemic activities and mechanisms of Acanthopanax senticosus (AS) herbal acupuncture. Methods : Anti-diabetic and anti-steatotic activity of the AS herbal acupuncture was investigated on C57BL/6J ob/ob mice. After random grouping at the age of 9 weeks, the herbal acupuncture groups were injected subcutaneously at the left and right Gansu (BL18) corresponding acupuncture points alternately on exactly the same time every day with 0.1ml of either 400 mg/kg or 800 mg/kg of AS (AS400 and AS800) for 8-week period. As a positive control, metformin was administrated at a dose of 300 mg/kg (MT300). Body weights were measured weekly, and on every other week blood was collected for blood glucose analysis. At the end of study, blood was also collected for determination of plasma insulin and lipid levels, after which they were killed and periepidydimal fat, liver, muscle, and pancreas were immediately removed. The removed tissues were instantly soaked in liquid nitrogen and stored at $-70^{\circ}C$ for morphological examination and mRNA analysis. Results : The AS herbal acupuncture significantly prevented weight gain on C57BL/6J ob/ob mice. The AS herbal acupuncture lowered blood glucose and improved glucose tolerance in C57BL/6J ob/ob mice. The increase of insulin response during the OGTT was inhibited by the AS herbal acupuncture. Insulin sensitivity of skeletal tissue was enhanced. Plasma lipid levels were significantly improved in the AS herbal acupuncture groups. The AS herbal acupuncture decreased hepatic lipogenesis and hepatic triglyceride production, and increased fatty acid (FA) transporter that involves in FA uptake. The AS herbal acupuncture inhibited the increase of liver mass by prevention of the accumulation of TG but did not inhibit weight gain of fat tissue on C57BL/6J ob/ob mice. Conclusion : In summary, we have demonstrated several unique properties of the AS herbal acupuncture in decreasing body weight, and reversing insulin resistance and hepatic steatosis in ob/ob mice. This AS herbal acupuncture acts as an insulin sensitizer and specifically decreases circulating glucose and lipids, and suppresses hepatic lipogenesis.

• 자원환경지질
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• 제42권5호
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• pp.427-434
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• 2009

유류 및 중금속으로 오염된 토양에서 Pb 및 Cd에 내성을 갖는 미생물을 분리하여 미생물 내 중금속 흡착 특성을 조사하였다. 분리한 토착미생물의 Pb 및 Cd의 흡착특성과 흡착에 영향을 미치는 요인 중에 생장단계, 중금속 농도, 생물량, pH, 온도에 따른 영향을 비교하였다. 또한 흡착등온식을 적용하여 중금속의 흡착용량과 흡착강도를 알아보았다. 낮은 중금속 초기 농도와 높은 생물량에서 높은 중금속 제거 효율을 가지며 중금속 마다 다른 흡착 효율을 보여 주었다. 흡착 효율은 미생물 생장 말기, pH 5~9 조건에서 최적의 효율을 나타내었으나, 25~$35^{\circ}C$에서 온도 변화에 따른 영향은 미미하였다. 생물흡착 과정을 Langmuir 등온 흡착식에 적용하면, 이론적 최대 흡착량은 Pb와 Cd에 대해서 각각 62.11과 192.31 mg/g로 나타났고, $R^2$가 0.71과 0.98로 계산되었다. Cd는 세포 표면의 단일 층에 단분자 흡착에 의한 생물흡착이 진행되었으나, Pb는 미생물 대사 작용을 통한 세포 내로의 축적 작용과 미생물 내 음이온과의 반응에 의한 침전물 형성작용 둥을 통하여 생물흡착이 진행된 것으로 판단된다.