不同温度下叶绿体毫秒延迟发光和质子区域化的关系

在０～１℃的低温条件下叶绿体毫秒延迟发光的快相明显较室温时的高,说明低温条件有利于水氧化所释放的质子在类囊体膜上形成区域化;磷酸化能在毫秒级范围内就利用水氧化所产生的区域化质子合成ＡＴＰ,使毫秒延迟发光的快相降低。随着温度升高,水氧化产生的区域化质子易向非区域化质子转变,２５℃时毫秒延迟发光的快相主要与膜电位有关而难以观察到水氧化所释放的质子的影响。水氧化产生的质子区域化与叶绿体膜的状态密切相关。     

Effect of artificial acid rain and SO2 on characteristics of delayed light emission.

The structure and function of chloroplast in plant leaves can be affected by acid rain and air pollution. The photosystem II in a plant is considered the primary site where light-induced delayed light emission (DLE) is produced. With the lamina of zijinghua (Bauhinia variegata L.) and soybean (Glycine max (L.) Merr.) as testing models, we studied the effects of artificial acid rain and SO2 on characteristics of DLE by using a home-made weak luminescence detection system. The results show that the changes in DLE intensity of green plants can reflect the changes in chloroplast intactness and function. With proper calibration, DLE may provide an alternative means of evaluating environmental acid stress on plants. The changes in DLE intensity may provide a new approach for the detection of environmental pollution and its impact on the ecosystem.     

The far red induced slow component of delayed light from chloroplasts is emitted from Photosystem II

In spinach chloroplasts illuminated with far red light, the relative intensity maximum during the decay of delayed light is emitted at 680–690 nm. This finding supports previous models predicting emission from Photosystem II, and contradicts earlier attributions to Photosystem I.Due to self absorption, the emission spectrum of the relative maximum is shifted to longer wavelengths and displays apparent Photosystem I characteristics in chloroplast samples of higher concentration or in leaves. This may have caused earlier investigators to ascribe the emission to Photosystem I.A differences between the spectral width of the emission spectra of delayed fluorescence and the relative maximum indicates that these two phenomena represent emission from different sub-populations of Photosystem II centers.Abbreviations PS I Photosystem I - PS II Photosystem II - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea     

Studies on thermoluminescence,delayed light emission and oxygen evolution from photosynthetic materials: UV effects

The effect of ultraviolet light on thermoluminescence, oxygen evolution and the slow component of delayed light has been investigated in chloroplasts and Pothos leaves. All peaks including peak V (48°C) were inhibited by UV. However, the peak at 48°C which was induced by DCMU was enhanced following UV irradiation of chloroplasts at ambient temperature (23°C) whereas peak II (-12°C) and peak III (10°C) which were also induced by DCMU were inhibited. Chloroplasts treated with DCMU and dark incubated for several minutes at ambient temperature prior to recording of glow curves have also shown enhancement of peak at 48°C. A slow component of delayed light and photosystem II activity of chloroplasts were inhibited by UV whereas photosystem I activity was marginally affected. These results corroborate involvement of photosystem II in generating thermoluminescence and slow components of delayed light in photosynthetic materials.Abbreviations DCIP Dichlorophenol Indophenol - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - DCQ 2,6 Dichloro-p-benzoquinone - DLE delayed light emission - MOPS Morpholino propane sulfonic acid - PSI Photosystem I - PS II Photosystem II - TL thermoluminescence     

Influence of State-2 transition on the proton motive force across the thylakoid membrane in spinach chloroplasts

The proton motive force (pmf) across the thylakoid membrane is composed of the proton gradient and the membrane potential, which promotes millisecond-delayed light emission (ms-DLE). In this study, the time courses of LHC II phosphorylation and ms-DLE were investigated in spinach chloroplast during State-2 transition. Red light illumination resulted in an exponential rise in LHC II phosphorylation and a biphasic time course of ms-DLE. The phospho-LHC II appeared upon ∼ 1 min illumination. The phosphorylation level increased exponentially when illumination was elongated to 20 min. The t_&frac; of saturated LHC II phosphorylation was estimated 4–5 min under present illumination. During this process, the amplitudes of ms-DLE increased transiently to a maximal amplitude within 0.5 min illumination, and the reached maximum of the fast phase of ms-DLE was ∼ 140% of the dark control. Then, ms-DLE decreased from the maximum. After ≥3 min illumination, ms-DLE decreased to a lower level than the dark control. In the presence of uncouplers and inhibitors, the transient increase in the biphasic time course of ms-DLE was removed by nigericin and DCMU, and the sequential decrease was delayed by DCCD. The time course was not affected significantly by valinomycin and DBMIB. Moreover, the level of LHC II phosphorylation was enhanced by nigericin, valinomycin and DCCD, and was inhibited completely by DCMU and partially by DBMIB. Taken together, we proposed that the PS II photochemical activity remained unaffected even with a higher level of LHC II phosphorylation, which was reflected by the effect of DCCD on the time course of ms-DLE. Probably, the evidence of LHC II phosphorylation is the rearrangement of LHC II–PS II complex and the thylakoid, a feedback to light-exposure, rather than the redistribution of excitation energy from PS II to PS I.     

Further characterization of a photosystem ii particle isolated from spinach chloroplasts by triton treatment delayed light emission

Delayed light emission from the Triton-fractionated Photosystem II subchloroplast fragments (TSF-IIa) was measured between 0.5 and 10 ms after the termination of illumination. The delayed light emission was diminished by Photosystem II inhibitors, DCMU and o-phenanthroline, which act between the reduced primary acceptor and the plastoquinone pool.Secondary electron donors to Photosystem II, diphenylcarbazide, phenylenediamine, Mn²⁺, and ascorbate inhibited delayed light emission. Secondary electron acceptors such as ferricyanide, dichlorophenol indophenol, and dimethyl benzoquinone enhanced delayed light emission. The addition of secondary electron acceptors to TSF-IIa particles containing Mn²⁺ restored delayed light emission to almost the control level. The plastoquinone antagonist, 2,5-dibromo-3-methyl-6-isopropyl p-benzoquinone, increased delayed light emission at low concentrations but decreased it at higher concentrations. Silicomolybdate enhanced the delayed light emission of TSF-IIa particles markedly, and reversed the inhibition by DCMU. Silicomolybdate showed a similar stimulatory effect on the delayed-light intensity in broken spinach chloroplasts at shorter times after the termination of illumination. Carbonyl cyanide m-chloro (or p-trifluoromethoxy) phenylhydrazones inhibited the delayed light emission, but NH₄Cl had no effect.     

The effect of light intensity on the assay of the low temperature limit of photosynthesis using msec delayed light emission

Steady state millisecond delayed fluorescence (DLE) of intact leaves and cyanobacterial cells was measured continuously with a Becquerel-type phosphoroscope while cooling from the growth temperature to near 0°C or heating from the low to high temperature at about 1°C/min. The temperature of maximum DLE depended upon light intensity. In Anacystis grown at 28 and 38°C DLE maximum occurred near 15 and 23°C, respectively, which are the temperatures where thylakoid membrane lipids have been shown to pass from the liquid crystalline to the mixed solid-liquid crystalline state in these cyanobacteria. In some plants such as field mallow DLE increased continuously as the temperature decreased, whereas in others it rose to a maximum, then decreased. Chilling-sensitive plants such as tomato, sweet potato and Trichospermum, showed DLE maxima around 10–14°C while the chilling-resistant plant, oat, had a maximum near 4°C and field mallow had no maximum above 0°C.Abbreviations DLE delayed light emission CIW-DPB Publ. No. 1022.     

Temperature dependence of delayed chlorophyll fluorescence in intact leaves of higher plants. A rapid method for detecting the phase transition of thylakoid membrane lipids

The temperature dependence of the yield of in vivo prompt and delayed chlorophyll fluorescence was investigated in maize and barley leaves. In the chilling-sensitive maize, delayed fluorescence at steady-state level showed a maximum near the temperature at which thylakoid membrane lipids undergo a phase transition as revealed by differential scanning calorimetry measurements. In the chilling-resistant barley, no phase transition was detected above 0°C and the delayed light emission varied in a monotonic fashion. It was shown that measurements of delayed luminescence intensity in vivo can provide a rapid and sensitive method for detecting the phase change of membrane lipids in intact leaves of chilling-sensitive plant species such as tomato, cotton, cucumber, castor bean or avocado. In contrast, the use of steady-state prompt chlorophyll fluorescence as an indicator of membrane fluidity change was not successful.     

Methane emission from a wetland plant: the role of CH4 oxidation in Eriophorum

The importance of plant-mediated CH₄ transport was studied in a northern wetland. CH₄ transport through Eriophorum, a dominant sedge, was found to be the major pathway for CH₄ fluxes. Mean emission from Sphagnum lawns was low (34 g CH₄ m^-2 h^-1) and significantly higher from tussocks of Eriophorum vaginatum (974 g CH₄ m^-2 h^-1; U-test, p < 0.05). Mean flux from single tillers of Eriophorum angustifolium was 92 g CH₄ h^-1. In contrast to other ecosystems, no CH₄ oxidation was associated with Eriophorum. Hence, the lack of oxidation is one reason for the high emission rates from these ecosystems. This finding is a caveat for models of CH₄ emission and may also have consequences for carbon flow models of northern wetlands.     

Studies on the protolytic reactions coupled with water cleavage in photosystem II membrane fragments from spinach

The protolytic reactions of PSII membrane fragments were analyzed by measurements of absorption changes of the water soluble indicator dye bromocresol purple induced by a train of 10 s flashes in dark-adapted samples. It was found that: a) in the first flash a rapid H⁺-release takes place followed by a slower H⁺-uptake. The deprotonation is insensitive to DCMU but is completely eliminated by linolenic acid treatment of the samples; b) the extent of the H⁺-uptake in the first flash depends on the redox potential of the suspension. In this time domain no H⁺-uptake is observed in the subsequent flashes; c) the extent of the H⁺-release as a function of the flash number in the sequence exhibits a characteristic oscillation pattern. Multiphasic release kinetics are observed. The oscillation pattern can be satisfactorily described by a 1, 0, 1, 2 stoichiometry for the redox transitions S_i S_i+1 (i=0, 1, 2, 3) in the water oxidizing enzyme system Y. The H⁺-uptake after the first flash is assumed to be a consequence of the very fast reduction of oxidized Q₄₀₀(Fe³⁺) formed due to dark incubation with K₃[Fe(CN)₆]. The possible participation of component Z in the deprotonation reactions at the PSII donor side is discussed.Abbreviations A protonizable group at the PSII acceptor side - BCP Bromocresol Purple - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - FWHM Full Width at Half Maximum - Q_A, Q_B primary and secondary plastoquinone at PSII acceptor side - Q₄₀₀ redox group at PSII-acceptor side (high spin Fe²⁺) - P680 Photoactive chlorophyll of PSII reaction center - S_i redox states of the catalytic site of water oxidation - Z redox component connecting the catalytic site of water oxidation with the reaction center     

弱光胁迫对花生功能叶片RuBP羧化酶活性及叶绿体超微结构的影响

间作套种是我国主要的花生(Arachis hypogaea)种植方式之一。然而, 与单作相比, 在间作套种体系中, 花生截获的光能较少, 生长发育差, 产量低, 研究不同品种耐阴机理对选择适宜间作套种的花生品种具有重要意义。该研究用耐阴性不同的两个花生品种‘花育22号’ (强耐阴性)和‘白沙1016’ (弱耐阴性)为材料, 在大田条件下采用不同透光率遮阴网设置50%自然光强(中度弱光胁迫)和15%自然光强(严重弱光胁迫) 2个弱光处理, 从出苗期开始遮阴40天, 以自然光强为对照, 研究了弱光胁迫对花生功能叶片RuBP羧化酶活性和叶绿体超微结构的影响。结果表明: 光强为自然光照50%和15%的处理, ‘花育22号’ RuBP羧化酶活性与对照相比虽有降低, 但差异不显著, 而‘白沙1016’分别比对照低40.1%和59.4%, 显著低于对照。与对照相比, 50%自然光强下‘花育22号’叶绿体数不变, 叶绿体基粒数和基粒片层数显著增多, 叶绿体变长且发育完好, 15%自然光强下, 叶绿体数、基粒数和淀粉粒数显著减少, 叶绿体膜和基粒片层出现破损, 但叶绿体变长, 基粒片层数增加; ‘白沙1016’在50%自然光强下, 叶绿体数目和超微结构变化同‘花育22号’相似, 在15%自然光强下叶绿体变圆, 基粒数的降幅和基粒片层破损程度大于‘花育22号’且基粒片层数减少, 淀粉粒数增多。因此, 弱光胁迫特别是严重弱光胁迫条件下, 功能叶RuBP羧化酶活性降低幅度小、叶绿体超微结构受损程度低是‘花育22号’耐阴的光合生理基础。     

Identification of far-red-induced relative increase in the decay of delayed light emission from photosynthetic membranes with thermoluminescence peak V appearing at 321 K

The relative increase in the decay of delayed light emission from photosynthetic membranes following far-red light excitation is shown to be related to thermoluminescence peak V appearing at 321 K. Peak V and the relative increase in the decay of delayed light emission show parallel changes in their intensities following far-red excitation.     

花粒期光照对夏玉米光合特性和叶绿体超微结构的影响

在大田条件下,以夏玉米品种‘登海605’为试验材料,研究花粒期不同光照强度(正常光照、开花至收获期遮阴和开花至收获期增光)对夏玉米叶片光合、荧光性能和叶绿体超微结构的影响.结果表明:与对照相比,花粒期遮阴影响叶绿体排布及内部结构发育,基粒个数和基粒片层数均有不同程度减少,叶片的净光合速率、蒸腾速率、气孔导度、叶绿素含量下降,PSⅡ反应中心的实际光化学效率和最大光化学效率降低,非光化学淬灭系数数值增加,导致产量降低;增光后叶绿体结构良好,基粒片层排列紧致、清晰且数量增加,PSⅡ反应中心的实际光化学效率增加,净光合速率、蒸腾速率、气孔导度、叶绿素含量上升,叶片光合性能增强,产量增加.即花粒期遮阴破坏了夏玉米叶片叶绿体超微结构,降低了叶片光合能力,产量下降;花粒期增光增加了叶肉细胞中叶绿体的基粒和基粒片层,导致基粒片层排列紧密有序,有利于增加作物产量潜力.     

CH4 emission from a hollow-ridge complex in a raised bog: The role of CH4 production and oxidation

The aim of this study was to correlate magnitude andcontrols of CH₄ fluxes with the microtopographyand the vegetation in a hollow-ridge complex of araised bog. High CH₄ emission rates were measuredfrom hollows and mud-bottom hollows, while hummocksconsumed atmospheric CH₄ at a low rate. Thehighest emissions were measured from plots with Eriophorum vaginatum and Scheuchzeriapalustris. CH₄ emission ceased after Scheuchzeria had been clipped below the water table,indicating the importance of this aerenchymatic plantas a conduit for CH₄.Peat in the upper catotelm of hollows was younger andless decomposed than in hummocks. Potential CH₄production in vitro was higher and themethanogenic association was better adapted to highertemperatures in hollow than in hummock peat. Highertemperatures in hollows resulted in a strongerCH₄ source in hollows than in hummocks. Negativefluxes from hummocks indicated that even in wetlandsmethanotrophic bacteria exist that are able to oxidizeCH₄ at atmospheric mixing ratios, and thatoxidation controls CH₄ emission completely. TheCH₄ mixing ratio was low in the acrotelm, but itincreased within the catotelm. Comparing fluxesmeasured in static chambers with fluxes calculatedfrom the porewater CH₄ profiles it was deducedthat the zone of methane oxidation was located closeto the water table.In hollows, CH₄ production at in situtemperature was far higher than emission into theatmosphere, corresponding to an oxidation rate ofnearly 99%. The CH₄ flux between the catotelmand the acrotelm of hollows was also higher than theemission, indicating the importance of CH₄oxidation in the aerobic acrotelm, too. CH₄microprofiles showed that CH₄ oxidation inmud-bottom hollows was confined to the topmost 2 mm,and that in Sphagnum-covered hollows CH₄oxidation occurred at the lower edge of green Sphagnum-parts.     

铁炉渣施加对稻田甲烷产生、氧化与排放的影响

为了阐明铁炉渣施加对稻田甲烷产生、氧化与排放的影响,采用静态箱-气相色谱法对对照(CK)、2 Mg/hm2(FeⅠ)、4Mg/hm2(FeⅡ)和8 Mg/hm2(FeⅢ)铁炉渣施加后稻田甲烷产生、氧化与排放进行了测定与分析.研究结果表明:观测期内,CK、Fe Ⅰ、FeⅡ和FeⅢ样地甲烷产生量分别为0.06-8.87、0.12-8.28、0.15-7.84、0.17-7.82 mg·m-2·h-1,平均产生量分别为4.68、3.92、3.14、2.76 mg·m-2·h-1;甲烷氧化量分别是0.02-1.27、0.09-0.95、0.09-1.54、0.09-2.79 mg·m-2·h-1,平均氧化量为0.46、0.47、0.59、0.55 mg·m-2·h-1;甲烷排放分别是0.04-7.99、0.03-7.33、0.06-6.30、0.08-5.12 mg· m-2·h-1,平均值分别为3.11、2.29、1.76、1.59 mg·m-2·h-1.铁炉渣的施加降低了甲烷产生量和排放通量,提高了甲烷氧化量.     

农林复合系统中物种间水肥光竞争机理分析与评价

低丘红壤农林复合系统被认为能通过引入树木而利用土壤深层水分及防治水土流失,从而作为亚热带地区应对季节性干旱的有效利用方式。然而,复合也可引起光能、水分和养分的竞争,导致农作物减产。通过作物生长量的测定、利用多年监测的土壤水文数据、15N微区试验及光合有效辐射的测量,综合探讨了南酸枣-花生复合系统引起的物种间水肥光的变化;通过其交互作用形成的协同,竞争关系分析,较为全面地评价了农林复合系统水肥光竞争特征。研究表明：低丘红壤上南酸枣与花生复合,促进了南酸枣生长,却减小了20％～50％的花生产量和生物量。其原因不单是南酸枣遮荫引起复合花生光合有效辐射减弱,还与水、肥竞争有关。复合系统在旱季加大利用50～100cm土层土壤水分,从而缓冲了干旱造成的影响;但南酸枣与花生间作系统也存在着一定的水分竞争。复合使得南酸枣能够利用施于花生区及淋失到60cm深处的养分,提高了养分的利用率;但同时也导致养分的竞争并影响花生的生长。在花生产量、生物量受复合南酸枣竞争影响因子中,以光最大、养分其次、水分最小。农林复合系统水肥光交互作用因其组分类型与时空配置而异,需从生态、经济、社会效益方面对复合模式加以优化。     

Studies on Halimeda IV. An endogenous rhythm of chloroplast migration in the siphonous green alga,H. distorta 1

Abstract

Halimeda has been found particularly suitable for studies of long‐distance chloroplast migration by virtue of its coenocytic structure and calcium carbonate skeleton. A circadian rhythm of chloroplast migration in Halimeda distorta was monitored by videography of segment surface pigmentation. In normal 12 h light/12 h dark treatments synchronised with dawn and dusk, the segments were green all day, began to become pale immediately the light was turned off, and then remained almost white for most of the night until beginning to re‐green a few hours before dawn. As a result of that, they were already quite green by the time the light was turned on. In continuous darkness a similar cycle, albeit with reducing amplitude and a period of about 23 hours, was maintained for at least 7 days. However, this cycle differed significantly from the normal one in that the segments did not remain green after the light was not switched on at dawn, but rather began to pale immediately thereafter. Conversely, in continuous light the segments did not become pale at any time. Thus, the rhythmical re‐emergence of the chloroplasts before dawn and their subsequent withdrawal appears to be controlled by an endogenous rhythm which is independent of light. However, light does completely, but reversibly, inhibit the chloroplast withdrawal component of the cycle. This behaviour of the chloroplasts in Halimeda is very similar to that in the related alga, Caulerpa, but it is quite different from that in another extensively Studied but unrelated siphonous green alga, Acetabularia, in which the circadian rhythm of chloroplast migration is maintained in continuous light.     

光质对番茄和莴苣幼苗生长及叶绿体超微结构的影响

采用发光二极管(LED)精确调制不同光谱能量分布,以荧光灯光照为对照,研究光质对番茄和莴苣幼苗生长及叶绿体超微结构的影响.结果表明：红光下番茄、莴苣幼苗的可溶性糖、淀粉和碳水化合物含量均显著高于对照,叶片叶绿体中淀粉粒膨大显著;蓝光极显著抑制了番茄下胚轴伸长,显著提高了莴苣和番茄幼苗叶片叶绿素a和类胡萝卜素含量;红蓝光下莴苣幼苗叶片的可溶性糖、淀粉、碳水化合物、蔗糖含量和C/N均达到最大值且显著高于红光处理,番茄和莴苣幼苗的主根显著伸长,幼苗叶片中叶绿体形态正常,基粒增多,基质片层清晰,淀粉粒体积明显小于红光处理.光质对植物幼苗的光形态建成、生长、碳氮代谢及叶绿体发育有显著影响;红光下光合产物积累显著但运输受阻严重,在红光中添加适量蓝光更有利于莴苣幼苗的碳水化合物积累,并可促进幼苗根系生长,有利于同化产物输出.     

Effect of back reactions in the S-cycle on photosynthesis in very weak light

Photosynthesis in light which is so weak that excitation rates are comparable to the decay rates of S-states is modelled. It is found that oxygen evolution rate varies in a non-linear way with Photosystem II excitation rate in this region, but asymptotically approaches a linear relationship (with a slope of one oxygen molecule per four excitations) as excitation rate increases. The asymptote gives an intercept (zero oxygen evolution rate) on the excitation rate axis. The question is raised, whether this model is compatible with photoautotrophy in a red alga found at 268 m depth and able to carry out photosynthesis in extremely weak light. It is found that no unorthodox mechanisms for the S-cycle in this alga have to be assumed to explain its performance.