Investigating energy partitioning during photosynthesis using an expanded quantum yield convention

Ahn, T.K.,Avenson, T.J.,Peers, G.,Li, Z.,Dall'Osto, L.,Bassi, R.,Niyogi, K.K.,Fleming, G.R. Elsevier Science Publishers [etc.] 2009 Chemical physics Vol.357 No.1

In higher plants, regulation of excess absorbed light is essential for their survival and fitness, as it enables avoidance of a build up of singlet oxygen and other reactive oxygen species. Regulation processes (known as non-photochemical quenching; NPQ) can be monitored by steady-state fluorescence on intact plant leaves. Pulse amplitude modulated (PAM) measurements of chlorophyll a fluorescence have been used for over 20 years to evaluate the amount of NPQ and photochemistry (PC). Recently, a quantum yield representation of NPQ (Φ<SUB>NPQ</SUB>), which incorporates a variable fraction of open reaction centers, was proposed by Hendrickson et al. [L. Hendrickson, R.T. Furbank, W.S. Chow, Photosynth. Res. 82 (2004) 73]. In this work we extend the quantum yield approach to describe the yields of reversible energy-dependent quenching (Φ<SUB>qE</SUB>), state transitions to balance PC between photosystems II and I (Φ<SUB>qT</SUB>), and photoinhibition quenching associated with damaged reaction centers (Φ<SUB>qI</SUB>). We showed the additivity of the various quantum yield components of NPQ through experiments on wild-type and npq1 strains of Arabidopsis thaliana. The quantum yield approach enables comparison of Φ<SUB>qE</SUB> with data from a variety of techniques used to investigate the mechanism of qE. We showed that Φ<SUB>qE</SUB> for a series of A. thaliana genotypes scales linearly with the magnitude of zeaxanthin cation formation, suggesting that charge-transfer quenching is largely responsible for qE in plants.

고추의 엽록소 형광 이미지 분석법에 의한 한발스트레스 지표화 가능성

유성녕(Sung-Yung Yoo),엄기철(Ki-Cheol Eom),박소현(So-Hyun Park),김태완(Tae-Wan Kim) 한국토양비료학회 2012 한국토양비료학회지 Vol.45 No.5

본 연구에서는 생육초기 고추의 한발 스트레스 조건에서 작물 생육에 미치는 영향을 구명하기 위해 엽록소 이미지형 광분석을 이용하여 엽록소 형광 매개변수를 비교분석 하였다. 비록 통계적 유의성이 인정되지는 않았지만 전체 잎의 이미지에 나타나는 형광매개변수들의 평균값은 감소하는 경향이었다. 가변형광값에대한 최대형광값의 비는 변동이 없는 반면, 광계II의 정류상태에서의 양자수득율 및 형광감쇄율은 다소 감소하였다. 이러한 현상은 퀴논 A 단백질로부터 퀴논 B 단백질로의 전자전달의 감소를 의미하였다. 잎의 중앙부위와 엽병부근에서의 비광학적 소광 및 가변형광의 비광학적 소광 상수는 한발스트레스 4일 후 유의성있게 증가하였다. 즉 생리적 스트레스 매개변수로 활용이 가능하였다. 광계Ⅱ에서의 정류상태 양자수득율의 감소는 고추잎의 모든 부위에서 공통적으로 유의성있게 측정되었다. 결론적으로 ΦPSⅡ (QY_LSS), NPQ_LSS, qN 등의 엽록소형광 매개변수들은 고추의 한발스트레스를 판단할 수 있는 생리적 지표로 활용 가능한 것으로 유의성이 인정되었다. The objectives of this study focused on measuring chlorophyll fluorescence related to drought stress comparing some parameters. Almost parameters were declined although they were not significant on the basis of mean values of fluorescence of total leaf area. While the ratio of fluorescence intensity variable chlorophyll (FV) to fluorescence intensity maximal chlorophyll (FM) was not changed, the effective quantum yield of photochemical energy conversion in photosystemII (ΦPSII) and chlorophyll fluorescence decrease ratio (Rfd) were slightly reduced, indicating inhibition of the electron transport from quinone bind protein A (QA) to quinone bind protein B (QB). Some parameters such as non-photochemical quenching rate (NPQ_LSS) and coefficients of non-photochemical quenching of variable fluorescence (qN) in mid-zone of leaf and near petiole zone leaf were significantly enhanced within 4 days after drought stress, which can be used as physiological stress parameters. Decrease in ΦPSII could was significantly measured in all leaf zones. In conclusion, three parametric evidences for chlorophyll fluorescence responses such as ΦPSII, NPQ, and qN insinuated the possibility of photophysiological indices under drought stress.

나노구조의 블랙-버네사이트를 이용한 퀴논계 화합물의 산화-변환 연구

한윤이(Yoo Ni Harn),최찬규(Chan Kyu Choi),신현상(Hyun Sang Shin) 大韓環境工學會 2010 대한환경공학회지 Vol.32 No.6

본 연구에서는 나노구조의 새로운 망간산화물 입자(즉, 블랙-버네사이트)를 합성하여 물질특성 및 1,4-naphthoquinone (1,4-NPQ)을 대상으로 반응매개체 존재 하에서의 산화-변환반응 효율을 조사하였고, 그 결과를 기존의 McKenzie 방법으로 얻은 망간산화물(즉, 브라운-버네사이트)의 결과와 비교 분석하였다. XRD 분석 결과 합성한 망간산화물 입자의 결정상은 버네사이트(δ-MnO₂)임을 확인하였으며, SEM 측정결과 입자표면은 섬유상의 구조에 의한 나노크기의 미세기공을 가진 볼모양(ball-like)의 형태를 보였다. 배치실험 결과, 나노구조의 망간산화물에 의한 1,4-NPQ 제거는 유사-1차 반응을 따랐으며 기존 망간산화물과 비교해 BET 비표면적 값이 작음(41.05vs 19.80m2/g)에도 불구하고 약 2.3배의 높은 속도 상수값을 보였다. 이러한 결과는 블랙-버네사이트에서의 상대적으로 높은 결정성과 나노구조의 표면 특성에 기인한 것으로 해석되며, 블랙-버네사이트 입자가 퀴논화합물에 대하여 상대적으로 높은 반응성을 보임을 알 수 있다. 반응산물에 대한 HPLC 크로마토그램 분석 결과로부터 블랙 버네사이트 입자에 의한 1,4-NPQ의 제거는 반응 매개체인 catechol 존재 하에서의 상호-결합반응을 통한 중합체 생성을 통해 제거됨을 확인하였다. In this study, new manganese oxide (i.e., black-birnessite) particles with nanostructures were prepared and its physico-chemical properties and oxidative-transformation efficiency on 1,4-naphthoquinine(1,4-NPQ) in the presence of reactive mediator was investigated. The results were also compared with that of the manganese oxide (i.e., brown-birnessite) particles synthesized by classical McKenzie method. Analysis of XRD and SEM data show that the particles are a single phase corresponding to a birnessite-based manganese oxide with cotton ball-like shapes containing nanofibers. In batch experiments, removals of 1,4-NPQ by the black-birnessite follows pseudo-first-order kinetics and the rate constant values obtained are greater about 2.3 times than that of the brown-birnessite in spite of its lower surface area (41.0vs 19.80m2/g). The results can be explained by the higher crystallinity and nano structured features of the back-birnessite particles, which give higher reactivity for the removals of the quinone compound. HPLC analysis of the reaction products confirmed that the balck-birnessites removed 1,4-NPQ through cross-coupling reaction in the presence of catechol as a reactive mediator.

Photodynamic Stress-Induced Nonenzymatic Antioxidant Responses in Transgenic Rice Overexpressing 5-Aminolevulinic Acid Synthase

Sunyo Jung(정선요) 韓國雜草學會 2011 Weed&Turfgrass Science Vol.31 No.4

색소체 transit 서열이 결여된 Bradyrhizobium japonicum ALA-S 유전자를 과발현하는 형질전환 벼의 광역학적 스트레스에 의해 유도되는 항산화반응을 조사하였다. 350 μmol m-2 s-1의 높은 광 수준은 야생형 벼에 비교하였을 때 형질전환 계통인 C4와 C5의 quantum yield를 감소시켰다. 대조적으로, 높은 광수준 하에서 형질전환 계통 C4와 C5의 nonphotochemicalquenching (NPQ) 수준은 야생형 계통과 낮은 광 수준 하의 형질전환 계통에 비해 높은 증가를 보여주었다. 형질전환 계통에서 높은 NPQ 수준은 xanthophyll인 zeaxanthin 수준의 증가와 밀접한 관련이 있었다. 150 μmol m-2 s-1의 낮은 광 수준과 비교하였을 때 높은 광 수준에서 violaxanthin 수준이 야생형 벼에서 증가하였으나, 형질전환 C4와 C5 계통에서는 현저하게 감소하였다. 형질전환 벼에서 nonphotochemical energy dissipation과 광보호기작을 가진 xanthophyll 색소가 광역학적 피해를 조절하는데 결정적인 역할을 하는 것으로 생각되나, 이러한 기작 이 광역학 스트레스를 극복하지는 못하였고 결과적으로 photobleaching 증상에 이르게 하였다. We investigated photodynamic stress-induced antioxidant responses in transgenic rice overexpressing Bradyrhizobium japonicum 5-aminolevulinic acid synthase (ALA-S) coding sequence lacking plastidal transit sequence. High light of 350 μmol m-2 s-1 decreased the quantum yield in the transgenic lines, C4 and C5, compared to that of wild-type line. By contrast, non-photochemical quenching (NPQ) levels of C4 and C5 under high light were higher than those of the transgenic lines under low light of 150 μmol m-2 s-1 as well as wild-type line under low and high light. Greater levels of NPQ in the transgenic lines exposed to high light were in a close correlation with increases in the xanthophyll pigment, zeaxanthin. Under high light, levels of neoxanthin, violaxanthin, lutein, and β-carotene in the transgenic lines were lower than those in wild-type line. Taken together, nonphotochemical energy dissipation and photoprotectant xanthophyll pigments play a critical role to deal with the severe photodynamic damage in the transgenic rice plants, although they could not overcome the photodynamic stress, leading to severe photobleaching symptoms.

Current Understanding of the Mechanism of qE, a Major Component of Non-photochemical Quenching in Green Plants

Zulfugarov Ismayil S.,Mishra Sujata R.,Han, Ok-Kyung,Safarova Rena B.,Nath Krishna,Lee, Choon-Hwan Korean Society of Photoscience 2005 Journal of Photosciences Vol.12 No.3

Plants dissipate excess excitation energy from their photosynthetic apparatus by a process called non-photochemical quenching (NPQ). The major part of NPQ is energy dependent quenching (qE) which is dependent on the thylakoid pH and regulated by xanthophyll cycle carotenoids associated with photosystem (PS) II of higher plants. The acidification of the lumen leads to protonation and thus conformational change of light harvesting complex (LHC) proteins as well as PsbS protein of PSII, which results in the induction of qE. Although physiological importance of qE has been well established, the mechanistic understanding is rather insufficient. However, recent finding of crystal structure of LHCII trimer and identification of qE mutants in higher plants and algae enrich and sharpen our understanding of this process. This review summarizes our current knowledge on the qE mechanism. The nature of quenching sites and components involved in this process, and their contribution and interaction for the generation of qE appeared in the proposed models for the qE mechanism are discussed.

자외선-B 스트레스에 대한 담배 잎의 광합성 능의 변화

이혜연 ( Hae Youn Lee ),박연일 ( Youn Il Park ),홍영남 ( Young Nam Hong ) 한국환경농학회 2007 한국환경농학회지 Vol.26 No.3

The effect of ultraviolet-B (UV-B) radiation on photosynthesis was studied by the simultaneous measurements of O2 evolution and chlorophyll (Chl) fluorescence in tobacco leaves. When the tobacco leaves were treated with UV-B (1 W·m-2), the maximal photosynthetic O2 evolution (Pmax; 4.60 μmol·m-2·s-1) at 200 μmol·m-2·s-1 was decreased with increasing time of UV-B treatment, showing 80% decline after 4 h treatment. Chl fluorescence parameters were also affected by ultraviolet-B. Fo was increased while both Fm and Fv were decreased, resulted in the decreased of photochemical efficiency of PSII (Fv/Fm). Non-radiative dissipation of absorbed light as heat as estimated as NPQ (Fm/Fm`-1) was also decreased with increasing time of UV-B treatment, while the extent of photochemical quenching (qP) was not changed. Thus, the ratio of (1-qP)/NPQ parameter was also increased with increasing time of UV-B treatment, indicating PSII is under the threat of photoinhibition. The results indicate that UV-B primarily decreases the capacity to dissipate excitation energy by trans-thylakoid pH, which in turn inhibits PSII activity.

차광처리에 따른 수리취의 광합성 관련 특성 변화

이경철,노희선,김종환,안수용,한상섭 한국약용작물학회 2012 한국약용작물학회지 Vol.20 No.5

This study was conducted to investigate the changes of chlorophyll contents, chlorophyll fluorescence, photosynthetic parameters, and leaf growth of Synurus deltoides under different shading treatments. S. deltoides was grown under non-treated (full sunlight) and three different shading conditions (Shaded 88~93%, 65~75%, and 45%~55%). Light compensation point (Lcomp), dark respiration (Dresp), maximum photosynthesis rate (Pnmax), photo respiration rate (Presp), carboxylation efficiency (Φcarb), and photochemical efficiency were decreased with increasing shading level; However, CO2 compensation point (CO2 comp), total chlorophyll content, and specific leaf area (SLA) were shown the opposite trend. S. deltoides under 88~93% treatment showed the lowest photosynthetic activity such as maximum photosynthetic rate (Pnmax), photochemical efficiency, and CO2 compensation point (CO2 comp). Therefore, photosynthetic activity will be sharply decreased with a long period of 8~12% of full sunlight. With the shading level decreased, carotenoid content and non-photochemical fluorescence quenching (NPQ) increased to prevent excessive light damage. This result suggested that growth and physiology of S. deltoides adapted to high light intensity through regulating its internal mechanism.

이산화티탄 처리와 몇 가지 작물 잎의 광화학적 스트레스

홍성창 ( Seung Chang Hong ),권순익 ( Soon Ik Kwon ),김민경 ( Min Kyeong Kim ),채미진 ( Mi Jin Chae ),황해 ( Hae Hwang ),정구복 ( Goo Bok Jung ),강기경 ( Kee Kyung Kang ) 한국환경농학회 2012 한국환경농학회 학술대회집 Vol.2012 No.-

Thermal Dissipation of Excess Light in Arabidopsis Leaves is Inhibited after Gamma-irradiation

( Yu Ran Moon ),( Jin Hong Kim ),( Min Hee Lee ),( Jae Sung Kim ),( Byung Yeoup Chung ) 한국식물학회 2008 Journal of Plant Biology Vol.51 No.1