• Journal of Plant Biology
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• 제31권4호
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• pp.299-307
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• 1988

The electron transport activities of choloroplasts isolated from hte detached rise (Oryza sativa L. cv. Chucheong) leave stored under low temperature(4$^{\circ}C$) with light illumination were investigated to understand the role of light in the low temperature inhibition of photosynthesis in the chilling-sensitive plants. Chlorophyll content of the detached leaves upon incubation at 28$^{\circ}C$ and 4$^{\circ}C$ in the dark was also measured. The rice seedlings were grown with Hoagland medium in the growth chamber of 28$^{\circ}C$ temperature and 400 ft.c fluorescent light with the photoperiod of 16 h. Although chlorophyll content of the detached leaves stored in the dark declined by 61.7% after 28$^{\circ}C$ treatement, there occurred only 5.2% decrease of chlorophyll with 4$^{\circ}C$ treatment. Low temperature treatment(4$^{\circ}C$) for 6 days brought about decreases in total photosystem(PS II＋PS I) activities by 35.2% and 73.6% in te presence and absence of light, respectively, while after 28$^{\circ}C$ treatment of the detached leaves for 6 days in the dark there was only 27.6% decrease in PS II＋PS I activity. PS II activities were also decreased by 35.6% and 72.2% in the light and dark, respectively. PS I activities were decreased slightly, however, by 7.6% and 16.2% in the light and dark, respectively. Investigations into DPClongrightarrowDCPIP and NH2OHlongrightarrowDCPIP activities revealed that low temperature inhibition of PS II activities was not due to the inactivation of the water oxidation capacity at low temperature. It was concluded that light protects the electron transport activities of isolated rice chloroplasts from the inhibitory effect of low temperature in the detached leaves.

• 농업과학연구
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• 제8권1호
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• pp.3-10
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• 1981

수도개체군(手稻個體群)의 생장(生長)과 수량(收量)을 생산생태자적관점(生産生態字的觀点)에서 해석(解析)하고저 그 생산구조(生産構造)와 평균생장속도(平均生長速度) 및 관련요인(關聯要因)의 영향(影響)을 구명(究明)하여 다음과 같은 결과(結果)를 얻었다. 1. 개체군하(個體群下)에서는 개체상태(個體狀態)보다 전생육기간(全生育期間)에 걸쳐 높은 평균생장속도(平均生長速度)를 지속(持續)하였으며 등숙기간(登熟期間)의 생장속도(生長速度)가 비교적(比較的) 높아 수량(收量)이 증가(增加) 하였다. 2. 벼의 개체군(個體群)이 평균생장속도(平均生長速度)를 높게 유지(維持)하였음은 순동화율(純同化率)보다 엽면적증대(葉面積增大)의 영향(影響)이 더 컸었다. 3. 개체군(個體群)서 품종(品種)에 따라서는 상위엽층(上位葉層)의 과번무(過繁茂)로 하위층엽(下位層葉)에 대(對)한 투광(透光)를 저해(沮害)하여 그 고사(枯死)를 많게 하였다. 4. 개체군(個體群)에서는 생육후기(生育後期)에 갈수록 동화기관(同化器官) 대(對) 비동화기관(非同化器官)의 비율(比率), 투광율(透光率) 및 엽신(葉身)의 질소함량(窒素含量)이 상대적(相對的)으로 저하(低下)하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제12권5호
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• pp.742-746
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• 1999

The potential of Leucaena leucocephala and Prosopis cineraria leaves as nitrogen supplements ($16g/kg\;W^{0.75}/d$) to improve the utilization of a basal diet of rice straw by goats was assessed in a feeding trial. Rice straw supplementation with forage oats (Avena sativa) was fed as a control diet. DMI, $g/kgW^{0.75}$ of rice straw by goats receiving Leucaena was significantly (p<0.05) higher followed by Prosopis and oat fodder. The supplementation of Leucaena improved the digestibility coefficient of DM, OM, CP, NDF and ADF nutrient density. Goats on Prosopis or oat fodder supplemented straw responded similarly in terms of nutrient utilization. The intake ($g/kgW^{0.75}$) of DCP, TDN and nitrogen balance of goats were significantly higher (p<0.05) when Leucaena was fed. It is suggested that the Leucaena may be a useful N-supplement in areas where livestock are fed poor quality crop residues.

• 한국작물학회지
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• 제44권3호
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• pp.296-301
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• 1999

The concerns on the crop damage by ultraviolet (UV) radiations is increasing owing to the decrease of their absorbing stratospheric ozone in the tropospheric. Cultivar differences on early growth of UV radiation among five Korean rice cultivars, four japonica types and one Tongil type (indica-japonica cross hybrid), were studied. Pot-seeded rice plants were grown under four different radiation conditions, i.e., visible radiation only, visible radiation with supplemented with high or low dose of UV-B (280~320 nm in wavelength) and UV-C (less than 280 nm in wavelength). The inhibitory degree on plant height, shoot and root weight and length of leaf blade and leaf sheath were determined at 40 days after seeding. UV-C showed the most severe inhibitory effect on the degree of biomass gain and leaf growth in most cultivars examined, followed by high UV-B and low UV-B. Among the cultivars used, the Kuemobyeo was the most sensitive cultivar and had not repair or showed resistance ability to continued irradiation of UV radiation. However, Janganbyeo and Jaekeon showed different responses that the elongation of leaf blades was promoted on 2nd and 3rd leaves and inhibited on 4th and 5th leaves but this inhibitory degree was reduced on 6 th and 7th leaves. Such tendency on leaf growth means that both cultivars had low sensitivity and most resistant ability to continued irradiation of UV radiation. While Tongil showed different response to enhanced UV radiation, ie., low UV-B promoted leaf growth but the inhibitory was severely increased by continued irradiation of high UV-B and UV-C, which means that Tongil had high threshold of UV radiation for response as an inhibitory light of plant growth. The results of this study indicate that the differences on sensitivity or resistant to the effects of UV radiation were existed among Korean rice cultivars.

• Molecules and Cells
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• 제40권10호
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• pp.773-786
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• 2017

The loss of green coloration via chlorophyll (Chl) degradation typically occurs during leaf senescence. To date, many Chl catabolic enzymes have been identified and shown to interact with light harvesting complex II to form a Chl degradation complex in senescing chloroplasts; this complex might metabolically channel phototoxic Chl catabolic intermediates to prevent oxidative damage to cells. The Chl catabolic enzyme 7-hydroxymethyl Chl a reductase (HCAR) converts 7-hydroxymethyl Chl a (7-HMC a) to Chl a. The rice (Oryza sativa) genome contains a single HCAR homolog (OsHCAR), but its exact role remains unknown. Here, we show that an oshcar knockout mutant exhibits persistent green leaves during both dark-induced and natural senescence, and accumulates 7-HMC a and pheophorbide a (Pheo a) in green leaf blades. Interestingly, both rice and Arabidopsis hcar mutants exhibit severe cell death at the vegetative stage; this cell death largely occurs in a light intensity-dependent manner. In addition, 7-HMC a treatment led to the generation of singlet oxygen ($^1O_2$) in Arabidopsis and rice protoplasts in the light. Under herbicide-induced oxidative stress conditions, leaf necrosis was more severe in hcar plants than in wild type, and HCAR-overexpressing plants were more tolerant to reactive oxygen species than wild type. Therefore, in addition to functioning in the conversion of 7-HMC a to Chl a in senescent leaves, HCAR may play a critical role in protecting plants from high light-induced damage by preventing the accumulation of 7-HMC a and Pheo a in developing and mature leaves at the vegetative stage.

• 식물병연구
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• 제21권2호
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• pp.103-106
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• 2015

벼 도열병은 벼의 조직에 따라서 잎, 마디, 목, 그리고 이삭의 병징에 의해 특성화된다. 심각한 수량 손실이 잎 도열병 보다는 목도열병과 이삭도열병이 원인이 됨에도 불구하고, 분리된 균주의 병원력 검정은 목과 이삭 대신 잎에서 수행되었다. 이 연구에서 우리는 목과 이삭 도열병을 위한 병원성 검정 방법을 개발하였다. 병원력 검정을 위해, 잎, 목, 그리고 이삭 도열병으로 부터 각각 3개의 대표균주를 선발하였다. 벼에 도열병균을 접종한 후 48시간 동안 고습도생장상에서 두었을 때, 24시간보다 목과 이삭에서 높은 발병률을 보였다. 잎 도열병 검정과 다르게, 목과 이삭에서의 전형적인 병반은 접종 14일 후 나타났다. 이 연구방법은 앞으로 벼 도열병의 벼 조직 별 병원성 검정방법을 위해 활용될 수 있을 것이다.

• Weed & Turfgrass Science
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• 제1권4호
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• pp.50-56
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• 2012

본 연구의 목적은 bar 유전자를 발현한 형질전환벼에 대한 글루타민 합성효소 저해제인 glufosinate-ammonium, L-metionine sulfoximine과 광합성저해제인 paraquat에 저항성 수준과 형질전환벼와 비형질전환벼의 암모늄 축적량, 저온반응 및 수량을 비교하는데 있다. 형질전환벼 계통은 비형질전환벼에 비해 glufosinate-ammonium에 45~95배 높은 저항성을 보였다. 한편 형질전환벼 계통은 L-metionine sulfoximine을 처리했을 때도 형질전환벼 계통이 비형질전환벼에 비해 18배 이상의 저항성을 보여 교차저항성이 있음을 확인할 수 있었다. 그러나 glufosinate-ammonium과 작용기작이 다른 제초제인 paraquat에 대한 다중저항성은 없었다. Glufosinate-ammonium 처리에 의해 ammonium 축적은 비형질전환벼에서 증가하였으나 모든 형질전환벼의 계통에서는 적거나 효과가 없었다. 형질전환벼 계통 258, 411, 607 및 608을 제외한 계통은 비형질전환벼에 비해 저온 내성 및 저온 후 회복정도가 유의적으로 낮은 경향을 보였다. 형질전환벼 계통 142, 144, 258 및 608의 수량은 비형질전환벼와 유사하거나 높았다.

• The Plant Pathology Journal
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• 제21권2호
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• pp.172-173
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• 2005

Until now, occurrence of Rice black-streaked dwarf virus (RBSDV) is observed in Gyeongsang provinces, southeastern part of Korea. However, recently, the occurrence of RBSDV is increasing and spreading in Jeonra provinces including Gochang-gun, southwestern part of Korea. RBSDV infected plants showed typical symptoms including stunted, deformed leaves with white waxy or black-streaked swelling along the veins. We extracted viral genomic dsRNA from infected leaves and analyzed dsRNA pattern by polyacrylamide gel electrophoresis. Ten genomic segments with similar sized dsRNAs were observed. We also detected RBSDV by reverse transcription (RT)-PCR using specific primers for S10 from genomic dsRNA and observed amplified DNA fragment specific for RBSDV S10.

• 한국작물학회지
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• 제47권4호
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• pp.301-304
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• 2002

The variation of alternative and cytochrome respiration during ripening in rice leaves (Oryza sativa L. cv. Takanari) was examined. The capacity of both respiration pathway was measured by inhibitor titration method using gas-phase oxygen electrodes. The alternative respiration rate decreased from 31.3% of the total respiration rate at around heading to 11.7% at 34 days after heading in the first fully expanded leaf from the top, and further to 6.4 % at 34 days after heading in the fourth leaf from the top. In contrast, the proportion of cytochrome respiration to total respiration increased with leaf senescence. The possible cause of alternative respiration as either an increase in inefficient respiration or a decrease in growth efficiency during ripening was discussed.

• 생명과학회지
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• 제19권4호
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• pp.442-448
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• 2009

대부분의 열대 식물은 chilling에 민감하게 반응한다. 대표적 열대 식물인 벼 잎에 대한 light-chilling 처리와 이 후의 회복기(post-chilling) 동안 일어나는 반응들을 알아보았다. Chilling 시 벼 잎에서의 광합성 효율($F_v/F_m$)은 대조구보다 50% 감소하였고, 상대적으로 $H_2O_2$ 양은 48% 증가하였다. 항산화 효소들 중 SOD와 GR 활성은 chilling과 post-chilling 시 증가하였다. 특히 SOD isoforms의 경우 CuZn-SOD와 Mn-SOD 가 발현된 반면 Fe-SOD는 발현되지 않았다. CAT 활성은 chilling 시 감소하였으며, 반면에 APX는 크게 증가하였다. Chilling 시 CAT의 isoforms의 변화를 보면, CAT-2와 -3의 활성이 감소한 것과 대조적으로 post-chilling 시 이들 isoforms의 활성은 증가하였다. 이처럼 APX와 CAT 활성은 벼 잎이 chilling stress를 겪게 될 때 상반되는 변화를 보여주었다.