• Journal of Photoscience
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• 제9권2호
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• pp.373-375
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• 2002

Lhcb genes encoding light-harvesting chlorophyll-a/b binding (LHC) proteins of photosystem (PS) II were comprehensively characterized using the expressed sequence tag (EST) databases in the green alga, Chlamydomonas reinhardtii. The gene family was composed of eight Lhcb genes including four new genes, which were isolated and sequenced. The effects of light intensity on the levels of mRNAs accumulation of multiple Lhcb genes were studied under various conditions. The results indicate that Lhcb genes are coordinately regulated in response to light conditions, and repressed when the input light energy exceeded the requirement for $CO_2$ assimilation. The effects of high light on the expression of the Lhcb genes observed in the presence of an electron transport inhibitor, DCMU, and in mutants deficient in photosynthetic reaction centers suggest the presence of two alternative mechanisms for regulating the genes expression under high-light conditions.

• 한국농림기상학회지
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• 제7권4호
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• pp.296-302
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• 2005

건조 스트레스에 의한 광합성 기구의 피해 양상을 파악하기 위하여 사시나무를 대상으로 광합성 특성의 변화를 조사하였다. 사시나무의 뿌리를 채취하여 근 맹아를 유도하고 각 개체를 증식한 후 실험에 사용하였다. 건조처리는 PEG농도를 무처리구인 대조구와 $0\%,\;2\%,\;5\%,\;and\;10\%$ 처리구로 구분하여, 주1회 300ml씩 관수하여 4주 후 광합성 특성과 광화학계 및 탄소고정계를 분석하였다 수분스트레스의 강도가 증가함에 따라 사시나무의 광합성속도, 기공전도도 및 증산속도는 모두 감소하는 경향을 보였다. 광화학계에서 PEG 처리농도의 증가는 PSII의 양자수율을 감소시켰으며, 이러한 전자에너지 전달의 감소는 순양자수율도 감소시켰다. 한편 호흡속도는 PEG 처리 농도가 증가함에 따라 감소하였으나, 탄소고정계의 광호흡속도는 반대로 증가하였다. 결론적으로 사시나무는 건조스트레스를 받으면 광합성관련 기구가 매우 민감하게 반응하며, 그들의 민감성은 수분스트레스의 강도에 좌우된다. 한편 사시나무는 수분이용효율의 증가와 같은 수분스트레스에 대한 내성 조절 능력을 보여준다.

• 한국해양학회지:바다
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• 제14권2호
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• pp.118-126
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• 2009

저서규조류는 하구역 먹이망을 이해하는 데 중요한 생물로서 그들의 광생리 특성에 따라 일차생산력이 크게 변화한다. 본 연구에서는 단기간 온도 변화가 저서규조류 4종(Navicula sp., Nitzschia sp., Cylindrotheca closterium, Pleurosigma elongatum)의 광합성 반응에 미치는 영향을 Diving PAM을 이용한 엽록소 형광 분석법으로 측정하여 광생리 특성을 분석하였다. 6개의 온도 조건(10, 15, 20, 25, 30, $35^{\circ}C$)에서 2시간 간격으로 24시간 동안 엽록소 형광을 측정하여 P-I 곡선을 도출하였다. 제2광계의 유효양자수율($\Phi_{PSII}$)은 대부분의 종에 있어서 온도가 증가함에 따라 감소하였으며, 상대 최대 전자전달율(rETRmax)은 최적 온도까지 증가한 후 급격하게 감소하였다. 최대 빛이용 효율($\alpha$)은 다른 광합성 매개변수에 비해 온도에 덜 민감하였으나, 높은 온도에서는 감소하였으며, 광포화 계수($E_K$)는 상대 최대 전자전달율의 반응과 매우 유사하였다. 종별 광생리 특성을 분석한 결과, Navicula sp.와 Cylindeotheca closterium가 광생리적 조절을 통하여 단시간의 온도 변화에 광순응하는 것을 확인할 수 있었다.

• Journal of Ginseng Research
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• 제22권2호
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• pp.102-113
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• 1998

This experiment used chlorophyll fluorescence techniques to assess the effect of irradiant during leaf development on photoinhibition of photosynthesis in Panax ginseng. Seedlings of p. ginseng were grown in the 91asshouse at four shade levels. The maximum mid-day irradiant in each treatment between emergence (January 4) and completion of the experiment (February 25) was 1220, 485, 235, 125 $\mu$mol/$\textrm{m}^2$/s. To assess the rapidity of photosynthetic readaptation to changes in light levels, fluorescence parameters (Fo, F, Fm, Fm', AF/Fm;, Fv/Fm) were measured for three days before and after transfer of plants (on February 21) from each light treatment into each of the other light treatments. Before transfer, dark adapted values of Fv/Fm in the 1220 (0.699) and 485 (0.739) treatments were different from each other and lower than values in the 235 (0.764) and 125 (0.768) treatments, indicating mild photoinhibition. Patterns of change in F during the day also differed between treatments, with low light treatments tracking irradiant levels, but F in the high light treatment (1220) declined in the morning, presumably due to fluorescence quenching. Although plants grown at high irradiant had relatively low photosynthetic efficiency, relative electron transport rate was greater than in lower irradiant treatments. After transfer, plants adopted the daily pattern of change in F of the treatment to which they were moved with little change in absolute levels of F, except in plants transferred from the highest (1220) to the lowest light level (125), where F increased over the course of the three days following transfer. After plants were transferred, Fm' converged on values similar to those in plants raised in the treatments to which they were moved. Values of Fv/Fm in plants moved from low to high light declined dramatically, but there was no decline in plants from 485 moved to 1220. Values of Pv/Fm in plants that were moved from high light to lower light increased to values above those recorded in plants raised in the lower light treatments. Reductions in quantum efficiency caused by photoinhibition at high irradiant may be more than compensated for by higher electron transport rates, although evidence suggests that under high irradiant this tends to be balanced by reduced leaf area and earlier senescence. Chlorophyll fluorescence techniques appear capable of indicating effects of irradiant induced stress in ginseng, yielding results comparable to those obtained with gas exchange techniques but in less time and with greater replication.

• 한국농림기상학회지
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• 제23권2호
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• pp.100-107
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• 2021

영농형 태양광은 동일 토지면적에서 태양광 패널에 의한 발전과 작물 경작을 융합한 시스템이다. 광 에너지가 부족한 영농형 태양광 하부에서 작물의 수확량이 감소하는 것은 필연적이나, 이를 관장하는 패널 하부에서 생육한 작물의 광합성 반응에 대해서는 국내외적으로 거의 알려진 바가 없다. 본 연구는 고정형 영농형 태양광 시설 하부에서 재배된 작물 잎에 흡수된 광에너지가 광합성 반응 중심에 전달되고 열로 방출되는 효율을 엽록소 형광 관측을 통해 조사하였다. 패널 하부와 노지의 콩과 벼는 ETR에서 큰 차이가 없는 것으로 보아 광인산화 효율보다는 잎이 흡수한 광 에너지에 따라 CO₂ 고정량이 결정되는 것으로 보인다. 또한, 패널 하부의 콩과 벼는 노지보다 NPQ가 더 높은 것으로 보아 활성화된 광보호기작이 광인산화로의 에너지 분배에 부정적 역할을 할 수 있을 것으로 보인다. 향후 영농형 태양광에서의 작물 생산량과 광합성의 관계를 이해하기 위해 보다 다양한 기후 및 재배조건에서의 광합성 반응을 조사할 필요가 있겠다.

• 한국잡초학회지
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• 제18권3호
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• pp.246-256
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• 1998

Metsulfuron-methyl 처리시 옥수수에 발현되는 자색화의 원인을 알아보기 위하여 제반실험을 수행하였다. Metsulfuron-methyl 처리시 농도와 시간에 의존하여 당과 anthocyanin의 함량이 증가되었고, 증가된 anthocyanin은 ILE+VAL이나 DCMU 처리에 의해서 경감되었다. 당을 외부로부터 공급하였을 때 당 농도에 의존하여 anthocyanin 함량이 증가되었고, 당형성이 제한되어 있는 백화조직에서는 metsulfuron-methyl 처리로 anthocyanin 생성이 증가되지 않았다. 그리고 metsulfuron-methyl은 광합성 자체를 억제하지 않았다. Metsulfuron-methyl에 의한 anthocyanin 축적을 구조 유전자 변이주 모두에서는 관찰할 수 없었고, 조절유전자 변이주 중에서는 R-r, r-r에서만 anthocyanin축적을 관찰할 수 있었다. 이들의 제반 결과는 metsulfuron-methyl이 처리되면 광합성 산물인 당이 축적되고, 이는 anthocyanin 생합성 과정에 관련된 유전자를 자극함으로써 anthocyanin 생합성과정을 활성화시키며 이로 인해 옥수수가 자색화됨을 시사해 준다.

• 환경생물
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• 제38권3호
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• pp.450-460
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• 2020

The occurrence of exotic weeds and their influx into farmlands due to climate change poses many problems. Therefore, it is necessary to generate a prediction model for the occurrence pattern of these exotic weeds based on scientific evidence and devise prevention measures. The photosynthetic apparatus is known as the most temperature-sensitive component of a plant cell and its initial response to temperature stress is to inhibit the activation of photosystem II. This study investigated the potential of OJIP transients in assessing temperature stress in exotic weeds. The four exotic weeds currently flowing into Korean farmlands include Amaranthus spinosus, Conyza bonariensis, Crassocephalum crepidioides, and Amaranthus viridis. These weeds were treated at 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, and 40℃ and the OJIP curves and JIP parameters were measured and analyzed. The results showed that heat and chilling stress affected the photosystem II(PSII) electron transport of A. spinosus, whereas C. crepidioides and A. viridis were more affected by high-temperature stress than by low-temperature stress. Lastly, C. bonariensis showed resistance to both high and low-temperature stress. The results of this study suggest that OJIP transients and JIP parameters can be used to analyze damage to the photosynthetic apparatus by temperature stress and that they can serve as sensitive indicators for the occurrence pattern of exotic weeds.

• Journal of Plant Biology
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• 제28권1호
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• pp.69-77
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• 1985

${Zn}^{2+}$이 엽록체의 광합성계에 미치는 영향을 구명코져 보리 엽록체를 사용하여 전자전달, 광인산화반응의 활성측정 및 전기영동에 의한 CP복합체의 안정성을 조사하였다. ${Zn}^{2+}$은 추출된 분리엽록체 조건에서 뿐아니라, 생육시 반응용액 조건에서도 전자전달, 특히, PS II의 활성을 저해하였으며, 이보다 광인산화활성을 더욱 더 크게 저해하였다. 전자전달능의 저해는 ${Mn}^{2+}$에 의하여 회복될 수 있었으며, 광인산화반응에서 ${Mg}^{2+}$과 ${Zn}^{2+}$는 서로 기능상의 경쟁을 나타냈다. 한편 전기영동에서 CP I은 ${Zn}^{2+}$과 mercaptoethanol이 존재하면 쉽게 파괴됨을 볼 수 있었다.

• Journal of Photoscience
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• 제1권1호
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• pp.47-52
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• 1994

Effects of HgCl$_2$-treatment on electron transport, chlorophyll a fluorescence and its quenching were studied using isolated barley (Hordeum vulgare L. cv. Albori) chloroplasts. Depending on the concentration of HgCI$_2$, photosynthetic oxygen-evolving activities of photosystem II (PS II) were greatly inhibited, whereas those of photosystem I (PS I) were slightly decreased. The inhibitory effects of HgCl$_2$ on the oxygen-evolving activity was partially restored by the addition of hydroxyamine, suggesting the primary inhibition site by HgCl$_2$2-treatment is close to the oxidizing site of PS tl associated with water-splitting complex. Addition of 50 $\mu$M HgCI$_2$ decreased both photochemical and nonphotochemical quenching of chlorophyll fluorescence. Especially, energy dependent quenching (qE) was completely disappeared by HgCl$_2$-treatment as observed by NH$_4$CI treatment. In the presence of HgCI$_2$, F'o level during illumination was also increased. These results suggest that pH gradient across thylakoid membrane can not be formed in the presence of 0 $\mu$M HgCl$_2$. In addition, antenna pigment composition might be altered by HgCl$_2$-treatment.

• Journal of Microbiology and Biotechnology
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• 제21권2호
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• pp.136-146
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• 2011

This study provides first-hand proteomic data on the survival strategy of Anabaena sp. PCC 7120 when subjected to long-term iron-starvation conditions. 2D-gel electrophoresis followed by MALDI-TOF/MS analysis of iron-deficient Anabaena revealed significant and reproducible alterations in ten proteins, of which six are associated with photosynthesis and respiration, three with the antioxidative defense system, and the last, hypothetical protein all1861, conceivably connected with iron homeostasis. Iron-starved Anabaena registered a reduction in growth, photosynthetic pigments, PSI, PSII, whole-chain electron transport, carbon and nitrogen fixation, and ATP and NADPH content. The kinetics of hypothetical protein all1861 expression, with no change in expression until day 3, maximum expression on the $7^{th}$ day, and a decline in expression from the $15^{th}$ day onward, coupled with in silico analysis, suggested its role in iron sequestration and homeostasis. Interestingly, the up-regulated FBP-aldolase, Mn/Fe-SOD, and all1861 all appear to assist the survival of Anabeana subjected to iron-starvation conditions. Furthermore, the $N_2$-fixation capabilities of the iron-starved Anabaena encourage us to recommend its application as a biofertilizer, particularly in iron-limited paddy soils.