CO2浓度倍增对垂柳和杜仲叶绿体吸收光能和激发能分配的影响

研究了CO_2浓度倍增对垂柳(Salix babylonica L.)和杜仲(Eucommia ulmoides Oliv.)叶片光合色素含量、叶绿体对光能吸收能力和激发能在两个光系统之间分配的影响。结果表明,CO_2 浓度倍增能提高垂柳叶片单位鲜重和单位叶面积叶绿素(Chl)和类胡萝卜素(Car)的含量;提高杜仲Chl含量,降低Car含量。CO_2浓度倍增能提高含等量Chl的叶绿体对光能的吸收和激发能在两个光系统间分配的调节能力。     

Effects of Doubled CO2 Concentration on the Content of Photosynthetic Pigments and PS II Functions of Jointing and Grouting in Setaria italica

Effects of doubled CO2 on the contents of chlorophyll and carotenoid per unit fresh weight and per unit area of leaves and PS Ⅱ functions of Setaria italica (L.) Beauv. were studied. The experimental results showed that the contents of chlorophyll and carotenoid, the proportion of opened PS Ⅱ reaction center from the mature leaves at jointing stage and the mature flag leaves at grouting stage were raised with CO2 enrichment. However, qN value and the overall photochemical quantum yield of PS Ⅱ , as well as the Fv/Fo, Fv/Fro and Fd/Fs in the above-mentioned leaves both at the jointing and grouting stage in response to doubled CO2 were different. The final outcome showed that the photosynthetic functions from the leaves at jointing stage improved by doubled CO2 were better than those from the flag leaves at grouting stage.     

盐胁迫下CO2加倍对春小麦一些光合功能的影响

 研究了在盐胁迫下CO2浓度加倍对春小麦(Triticum aestivum)青323光合色素含量和一些光合功能的影响。结果表明,盐胁迫降低春小麦叶片单位鲜重叶绿素(Chl)和类胡萝卜素(Car)的含量、叶绿体对光能的吸收能力,Mg2+对两个光系统(PSⅡ和PSⅠ)之间激发能分配的调节能力,以及荧光猝灭速率(△FV/T)。然而,CO2加倍有提高上述各参数的作用,表明高CO2浓度能减轻盐胁迫对光合功能的不利效应。     

CO2浓度倍增对谷子拔节期和灌浆期光合色素含量和PSⅡ功能的影响

研究了CO_2浓度倍增对谷子(Setaria italica (L.)Beauv.)叶片单位鲜重和单位叶面积叶绿素(Chl)和类胡萝卜素(Car)的含量以及PSⅡ功能的影响。结果表明,CO_2浓度倍增能提高拔节期成熟叶片和灌浆期成熟旗叶的Chl和Car的含量,并且能提高这两种叶片PSⅡ反应中心开放部分的比例。然而拔节期叶片和灌浆期旗叶的qN值和PSⅡ总的光化学量子产量,以及 F_v/F_o、F_v/F_m和F_d/F_s的值对CO_2浓度倍增的响应不同,表明CO_2浓度倍增对拔节期叶片光合功能的改善优于灌浆期的旗叶。     

Effects of Doubled CO2 on Contents of Photosynthetic and on Kinetic Parameters of Fluorescence Induction in Different Genotypes of Soybean

Effects of doubled C02 on photosynthetic characteristics of soybean ( Glycine max L. ) Bragg (wild type) and its different monogene mutation strains--Nts 382 (supemodulation mutant) and Nod 49 (non-nodulation mutant) were studied. The experimental results showed that the contents of chlorophyll and carotenoid of Bragg, Nts 382 and Nod 49 were increased under doubled CO2, respectively, although to different extent. The determination results of fluorescence induction kinetic parameters showed that PS Ⅱ activity, the efficiency of primary conversion of light energy of PS Ⅱ and the efficiency of potential photosynthetic quantum conversion of a leaf from Bragg and its mutants were raised in doubled CO2. Fluorescence photochemical quenching coefficient and the overall photochemical quantum yield of PS Ⅱ were raised and non-photochemical quenching coefficient was reduced with CO2 enrichment; such changes were bigger in Nts 382 than those in Bragg and Ned 49. It might be that atmospheric N2 was more effectively utilized by Nts 382 than by Bragg and Ned 49.     

Greening of intermittent-light-grown bean plants in continuous light: thylakoid components in relation to photosynthetic performance and capacity for photoprotection

Phaseolus vulgaris (cvv. Windsor longpod and snap bean) plants, etiolated during germination, were exposed to intermittent light (2 min light every 2 hr) for up to 68 hr and then transferred to continuous white light. On transfer of the plants to continuous light (100 photons mumol m-2 s-1, 24 degrees C), the quantum yield of oxygen evolution increased two-fold in about 30 hr. The chlorophyll content per unit leaf area or unit fresh weight increased dramatically, but the fresh weight per unit leaf area was relatively constant. The changes were expressed on the basis of fresh weight or leaf area. On this basis, the contents of photosystem (PS) I and II increased in continuous light, by a factor of 3 and 8, respectively. While the chlorophyll b content and the contents of apoproteins of light-harvesting chlorophyll-protein complexes (LHCIIb, CP29, CP26 and CP24) increased markedly, neither the total carotenoid content nor the de-epoxidation state of the xanthophylls [ratio of zeaxanthin(Z) + antheraxanthin(A) to (Z + A + violaxanthin) was about 0.4)] responded significantly on transfer to continuous light. The fast rise of the flash-induced electrochromic signal (delta A518) was well correlated with the increases in PS I and PS II reaction centres, and with chlorophyll b and total carotenoid contents. The increase in the quantum yield of oxygen evolution during greening in continuous light is attributed to a more balanced distribution of excitation energy between the two photosystems, facilitated by the increased number of PS II units, the increased antenna size of each unit and the enhancement of grana formation. The chloroplast in intermittent light was found to contain abundant xanthophyll cycle pigments and the psbS gene product, presumably adequate for photoprotection in continuous light as soon as chlorophyll a/b- protein complexes are synthesized. The results suggest that greening in continuous light is accompanied by adjustments that include enhanced quantum efficiency of photosynthesis and development of a capacity for harmless dissipation of excess excitation energy.     

A single step separation of PS 1, PS 2 and chlorophyll-antenna particles from spinach chloroplasts

After solubilization of photosynthetic membranes by digitonin, three main protein pigment complexes were isolated by electrophoresis with deoxycholate as detergent.The band with the slowest mobility, fraction 1, had PS 1 activity and was devoid of PS 2 activity. This fraction was four times enriched in P700 when compared with chloroplasts. Fraction 1 had little chl b, a long wavelength absorption maximum in the red, a maximum of low temperature emission fluorescence at 730nm, and a circular dichroism spectrum characteristic of PS 1 enriched fraction.Fraction 2 exhibited a PS 2 activity and no PS 1 activity. It was enriched five times in PS 2 reaction centre and had little chl b and carotenoids. The absorption maximum was at 674 nm and the low temperature fluorescence emission maximum was at 700 nm. Fraction 2 might be useful PS 2 enriched particle because of the great stability of this fraction with regard to photochemical activity and also rapidity and simplicity of its preparation.Fraction 3, which had the fastest migration, was devoid of photochemical activities; It was rich in chl b and had the fluorescence and the circular dichroism spectrum characteristic of an antenna complex.Abbreviations PS 1 (2) photosystem 1 (2) - chl chlorophyll - car carotenoid - Q primary plastoquinone electron acceptor - P700 primary electron donor of PS 1 - P680 primary electron donor of PS 2 - K₃Fe(CN)₆ potassium ferricyanide - DCMU dichlorophenyldimethylurea - DCPIP dichlorophenolindophenol - DPC diphenyl-carbazide     

施氮和大气CO2浓度升高对小麦旗叶光合电子传递和分配的影响

采用开顶式气室盆栽培养小麦,设计2个大气CO2浓度(正常:400 μmol.mol-1;高:760 μmol·mol-1)、2个氮素水平(0和200 mg·kg-1土)的组合处理,通过测定小麦抽穗期旗叶氮素和叶绿素浓度、光合速率(Pn)-胞间CO2浓度(C1)响应曲线及荧光动力学参数,来测算小麦叶片光合电子传递速率等,研究了高大气CO2浓度下施氮对小麦旗叶光合能量分配的影响.结果表明:与正常大气CO2浓度相比,高大气CO2浓度下小麦叶片氮浓度和叶绿素浓度降低,高氮处理的小麦叶片叶绿素a/b升高.施氮后小麦叶片PSⅡ最大光化学效率(Fv/Fm)、PSⅡ反应中心最大量子产额(Fv'/Fm')、PSⅡ反应中心的开放比例(qr)和PSⅡ反应中心实际光化学效率(φPSⅡ)在大气CO2浓度升高后无明显变化,虽然叶片非光化学猝灭系数(NPQ)显著降低,但PSⅡ总电子传递速率(JF)无明显增加;不施氮处理的Fv'/Fm'、φPSⅡ和NPQ在高大气CO2浓度下显著降低,尽管Fv/Fm和qp无明显变化,JF仍显著下降.施氮后小麦叶片JF增加,参与光化学反应的非环式电子流传递速率(Jc)明显升高.大气CO2浓度升高使参与光呼吸的非环式电子流传递速率(J0)、Rubisco氧化速率(V0)、光合电子的光呼吸/光化学传递速率比(J0/Jc)和Rubisco氧化/羧化比(V0/Vc)降低,但使Jc和Rubisco羧化速率(Vc)增加.因此,高大气CO2浓度下小麦叶片氮浓度和叶绿素浓度降低,而增施氮素使通过PSⅡ反应中心的电子流速率显著增加,促进了光合电子流向光化学方向的传递,使更多的电子进入Rubisco羧化过程,Pn显著升高.     

Effects of Light intensity on Photosynthetic Characteristics of Wheat Seedling

The contents of pigments and chlorophyll-protein complexes, fluorescence characteristics and electron transport rate were compared for wheat seedlings grown under different light intensities. Leaves of wheat seedlings grown under low-light intensity (2 klx) had lower chlorophyll and carotenoid contents on leaf area or fresh weight basis, a lower ratio of chlorophyll a/b, lower CPIa and CPI contents in photosynthetic membranes than those of wheat seedlings grown under high-light intensity (20 klx). However, the LHCP content in photosynthetic membranes was higher in the former. The kinetic studies of fluorescence induction showed that wheat seedlings grown under low-light intensity possessed a bigger photosynthetic unit, lower PSⅡ activity and lower efficiency of primary energy conversion than those grown under high-light intensity. Moreover. lower electron transport rate was found in the chloroplasts of the former.     

Theoretical assessment of alternative mechanisms for non-photochemical quenching of PS II fluorescence in barley leaves

The components of non-photochemical chlorophyll fluorescence quenching (qN) in barley leaves have been quantified by a combination of relaxation kinetics analysis and 77 K fluorescence measurements (Walters RG and Horton P 1991). Analysis of the behaviour of chlorophyll fluorescence parameters and oxygen evolution at low light (when only state transitions — measured as qN_t — are present) and at high light (when only photoinhibition — measured as qN_i — is increasing) showed that the parameter qN_t represents quenching processes located in the antenna and that qN_i measures quenching processes located in the reaction centre but which operate significantly only when those centres are closed. The theoretical predictions of a variety of models describing possible mechanisms for high-energy-state quenching, measured as the residual quenching, qN_e, were then tested against the experimental data for both fluorescence quenching and quantum yield of oxygen evolution. Only one model was found to agree with these data, one in which antennae exist in two states, efficient in either energy transfer or energy dissipation, and in which those photosynthetic units in a dissipative state are unable to exchange energy with non-dissipative units.Abbreviations: F_o, F_m room-temperature chlorophyll fluorescence yield with all centres open, closed - F_v variable fluorescence yield - LHC II light-harvesting chlorophyll-protein complex of PS II - PS I, PS II Photosystem I, II - P700, P680 primary donor in Photosystem I, II - Q_A primary electron acceptor of PS II - P_max maximum quantum yield of oxygen evolution - qN coefficient of non-photochemical quenching of variable fluorescence - qN_e, qN_t, qN_i coefficient of non-photochemical quenching due to high-energy-state, state transition, photoinhibition - qO coefficient of quenching of dark level fluorescence - qP coefficient of photochemical quenching of variable fluorescence - _P intrinsic quantum yield of open PS II reaction centres = _s/qP - _{PS 2} quantum yield of PS = qP × F_v/F_m - _S quantum yield of oxygen evolution = rate of oxygen evolution/light intensity     

Multiple deletions of small Cab-like proteins in the cyanobacterium Synechocystis sp. PCC 6803: consequences for pigment biosynthesis and accumulation

Deletion of the genes for four or five small Cab-like proteins (SCPs) in photosystem (PS) I-less and PS I-less/PS II-less strains of Synechocystis sp. PCC 6803 caused a large decrease in the chlorophyll and carotenoid content of the cells without accumulation of early intermediates in the chlorophyll biosynthesis pathway, suggesting limited chlorophyll availability. The PS II/PS I ratio increased upon deletion of multiple SCPs in a wild type background, similar to what is observed in the presence of subsaturating concentrations of gabaculin, an inhibitor of an early step in the tetrapyrrole biosynthesis pathway. Upon deletion of multiple SCPs, neither 77 K fluorescence emission properties of phycobilisomeless thylakoids from the PS I-less/PS II-less strain nor the energy trapping efficiency of PS II were affected, indicating that under steady-state conditions SCPs do not bind much chlorophyll and do not serve as PS II antenna. Under conditions where protochlorophyllide reduction and thus chlorophyll synthesis were inhibited, chlorophyll disappeared quickly in a mutant lacking all five SCPs. This implies a role of SCPs in stabilization of chlorophyll-binding proteins and/or in reuse of chlorophylls. Under these conditions of inhibited reduction of protochlorophyllide, the accumulation kinetics of this intermediate were greatly altered in the absence of the five SCPs. This indicates an alteration of tetrapyrrole biosynthesis kinetics by SCPs. Based on this and other evidence, we propose that SCPs bind carotenoids and transiently bind chlorophyll, aiding in the supply of chlorophyll to nascent or reassembling photosynthetic complexes, and regulate the tetrapyrrole biosynthesis pathway as a function of the demand for chlorophyll.     

假根羽藻外周天线色素分子间能量传递

假根羽藻外周天线捕光色素蛋白复合物(L ight-harvesting Comp lex II,LHC II)在不同聚集态的情况下,它所包含色素分子间的能量传递是不同的。采用荧光发射光谱和激发光谱技术对不同聚集态(单体、三聚体和寡聚体)的LHC II进行研究,发现三聚体中色素分子间的能量传递效率比较高,单体要小一些。520 nm激发下,类胡萝卜素分子向叶绿素a分子的能量传递效率:三聚体约为64%、单体约为56%;650 nm激发下,叶绿素b分子向叶绿素a分子的能量传递效率:三聚体约为89%、单体约为78%。寡聚体的能量传递要复杂些,从光谱分析出它包含两种不同吸收光谱特性的叶绿素b分子,吸收峰分别为480 nm和468 nm,其中蓝区吸收峰为480 nm的叶绿素b分子向发射685 nm荧光的叶绿素a分子的能量传递效率要小于75%。     

Changes in CO2 Exchange Rate,Stomatal Conductance,Activities of Photosystems 1 and 2, and Chloroplast Polypeptide Profile Induced by Simulated Acidic Rain

In seedlings of Vigna radiata (L.) R. Wilczek cultivars ADT-1 and CO-5 exposed to acidic showers (H2SO4 : HNO3 : HCl, 4 : 2 : 1, v/v) of different pH (7.0, 5.5, 4.0, and 2.5) for 10 d, net CO2 uptake and stomatal conductance were reduced. The chlorophyll (Chl) a and b contents were reduced but the carotenoid (Car) content increased. In vivo Chl a fluorescence patterns of both the cultivars were altered. No significant change in photosystem (PS) 1 activity was observed except at pH 2.5 where an inhibition was evident. By contrast, PS2 activities declined rapidly with increasing acidity. The room temperature absorption spectra of isolated chloroplasts showed very little changes. SDS-PAGE analysis revealed depletion of 23, 33, and 55 kDa polypeptides. Cultivar CO-5 was more sensitive to acidic rain than cv. ADT-1.     

Steady State of Photosynthesis in Cyanobacterial Photosynthetic Systems Before and After Regulation of Electron Transport Composition: Overall Rate of Photosynthesis and PSI/PS II Composition

The effect of regulation of photosystem (PS) composition onthe photosynthetic steady state was examined using the cyanobacteriumSynechocystis PCC 6714. Photosynthetic rates under orange lightabsorbed by phycobiliprotein (PBP) (PBP light) and under redlight absorbed mainly by chlorophyll a (Chi a light) were comparedfor the cells before and after adaptation to the respectivelight regimes. Results were as follows: (1) Photosynthetic ratesper absorbed light quantum became higher after adaptation thanthose before adaptation. (2) Under Chi a light, the low turnoverrate of PS I before adaptation was markedly enhanced after adaptation(decrease in PS I content), but in the case of adaptation toPBP light (increase in PS I content), a marked enhancement ofPS II turnover occurred after adaptation. (3) In the formercase, a low turnover rate of PS I before adaptation was dueto the occurrence of a large number of closed PS I complexes,but in the latter, limited excitation of PS I caused a largenumber of closed PS II complexes before adaptation. Resultsfor the latter case indicate that the energy transfer from phycobilisome(PBS) to one PS I complex is far smaller than that from PBSto one PS II complex, and that the imbalance of energy distributionfrom PBS to the two photosystems is compensated for by the increasein the number of PS I complexes. (Received September 10, 1987; Accepted December 9, 1987)     

A comparison of chlorophyll a and carotenoid concentrations as indicators of algal volume

SUMMARY. 1. Carotenoid concentration, as measured hy absorbance at 480 nm. was a better indicator of algal volume than chlorophyll a when the results from two lakes and laboratory studies on Osciltaloria agardhii var. isothrix Skuja were compared. The correlation between algal volume and carotenoid in White Lough ( r =0.91) was significantly higher (0.001 P <0.01) than ihat between algal volume and chlorophyll a (r=0.77). The Lotigh Neagh correlation coefficient lor algal volume with carotenoid (r=0.89) was only marginally stronger than that with chlorophyll a (r=0.87).
2. The relatively weak correlation between algal volume and chlorophyll a in White Lough was a result of a summer decline in the chlorophyll a content of O. agardhii var. isothrix , which dominated the phytoplankton. The chlorophyll a content of the phytoplankton was depressed by high summer daily totals ol light hours received by the phytoplankton in White Lough of up to 14 h in comparison to a maximum value of 3.8 h in Lough Neagh. where no seasonal cycle of chlorophyll a content was evident.
3. Laboratory studies demonstrated that while chlorophyll a per unit algal volume of O. agardhii var. isothri.x declined with increasing light dose, carotenoid content did not. Nitrogen and phosphorus limitation depressed the carotenoid content but to a lesser degree than was observed for chlorophyll a.     

二氧化碳加富对大豆叶片光系统II功能的影响

 本文研究了长期CO2加富对大豆叶片光系统Ⅱ(PSⅡ)功能的影响。结果表明,CO2加富能促进大豆叶片PSⅡ潜在活性和原初光能转化效率,以及电子传递量子产量的提高;增加荧光光化学淬灭组分,降低荧光非光化学淬火组分。CO2加富对大豆叶片PSⅡ功能的改善,可能是CO2加富条件下,大豆叶片光合速率的提高和产量增加的重要原因之—。     

实生和嫁接槐树的枝梢生长与光合特性

测定槐树实生树和嫁接树叶片的光合光响应特性、比叶重和叶绿素含量及枝梢生长的结果表明,嫁接树枝梢基径和高度增长趋势与实生树一致,但嫁接树一次、二次梢基径和高度增长量均大于实生树。嫁接树的最大净光合速率、光饱和点、比叶重和单位重量的叶绿素含量均显著高于实生树,高的光合能力与其单位面积叶片重量增加和单位重量叶绿素含量增高有关。嫁接槐树的类胡萝卜素与叶绿素比值高于实生槐树,叶绿素a,b比值和单位重量类胡萝卜素含量显著高于实生槐树,表明其对强光的适应性强。     

Effects of Manganese Deficiency on Spectral Characteristics and Oxygen Evolution in Maize Chloroplasts

The effects of Mn²⁺ deficiency on light absorption, transmission, and oxygen evolution of maize chloroplasts were investigated by spectral methods. Several effects of Mn²⁺ deficiency were observed: (1) the skeleton of pigment protein complexes and oxygen-evolving center and the combination between pigment and protein were damaged; (2) the light absorption of chloroplasts was obviously decreased; (3) the energy transfer among amino acids within PS II protein–pigment complex and decreased energy transport from tyrosine residue to chlorophyll a and from chlorophyll b and carotenoid to chlorophyll a were inhibited; (4) the oxygen-evolving of chloroplast was significantly inhibited. However, Mn²⁺ addition decreased the damage of light absorption, transmission, and oxygen evolution of maize chloroplasts caused by Mn²⁺ deficiency.     

Effect of light intensity on pigments and main acyl lipids during ‘natural’ chloroplast development in wheat seedlings

The content and composition of pigments and acyl lipids (monogalactosyl diacylglycerol, digalactosyl diacylglycerol and phosphatidyl glycerol) have been investigated in developing chloroplasts isolated from successive 2-cm sections along the leaves of wheat seedlings grown either under 100, 30 or 3 W·m^-2. In all examined stages of plastid development chlorophyll a/b and chlorophyll/carotenoid ratios were higher with increasing irradiance, whereas chlorophyll content expressed on fresh weight basis gradually decreased.Concentrations of monogalactosyl diacylglycerol, digalactosyl diacylglycerol and phosphatidyl glycerol decreased per chlorophyll unit with increasing plastid maturity. The higher was the light intensity applied during plant growth, the higher were galactolipid and phosphatidyl glycerol contents in developing chloroplasts. During plastid development the percentage of -linolenic acid markedly increased in total and individual acyl lipids. Under high light conditions, the accumulation of this fatty acid proceeded more rapidly. Significantly higher proportion of -linolenic acid was found in acyl lipid fraction of chloroplasts differentiating in high light grown plants, than in those from plants exposed to lower light intensities. The differences in the double bond index may indicate higher fluidity of thylakoid membranes in sun-type chloroplasts.Trans-3-hexadecenoic acid, virtually absent in the youngest plastids, was found in much higher concentration (per chlorophyll unit and as mol % of phosphatidyl glycerol fatty acids) in chloroplasts developing at high light conditions.Abbreviations MGDG monogalactosyl diacylglycerol - DGDG digalactosyl diacylglycerol - PG phosphatidyl glycerol - PC phosphatidyl choline - DBI double bond index - PS I photosystem I - PS II photosystem II - PSU photosynthetic unit - LHCP light harvesting chlorophyll-protein complex     

Light-harvesting pigment-proteins of photosystem I in maize. Subunit composition and biogenesis

Three different pigment-binding proteins of the light-harvesting complex (LHC I) of maize photosystem I (PS I) have been isolated. Absorption and fluorescence excitation spectral analyses showed that each pigment-protein can transfer absorbed energy from its carotenoid and/or chlorophyll b components to chlorophyll alpha. Their apoproteins with apparent sizes of 24 (LHC Ia), 21 (LHC Ib), and 17 (LHC Ic) kDa have been purified to homogeneity. Differences in their pigment and amino acid compositions and in their reactions with antibodies demonstrate that the two smaller pigment-proteins are not proteolytically derived from the largest one. LHC Ib's apoprotein is particularly enriched in cysteine residues. None of the three apoproteins cross-reacted with antibodies raised against the major light-harvesting chlorophyll a/b-protein of photosystem II (LHC IIb) or against the PS I core complex (CC I) subunits. Studies of the biogenesis of PS I during greening of etiolated plants showed that all of the CC I subunits accumulated to a detectable level prior to the appearance of the 17-kDa subunit of LHC I, the accumulation of which preceded those of the 24- and 21-kDa subunits of LHC I. In addition, subunit VI of CC I is shown to be differentially expressed in mesophyll and bundle sheath cells; a slightly larger form of it accumulates in mesophyll than in bundle sheath thylakoids during plastid development.