Mg2+对生长在不同光强下的小麦叶绿体光合功能的影响

研究结果表明,Mg~(2+)对生长在不同光强度下的小麦叶绿体光合功能有不同影响。与生长在低光强(2×10~8勒克斯)下的小麦叶绿体相比,Mg~(2+)更加明显地降低从生长在高光强(2×10~4勒克斯)下的小麦所分离的叶绿体的吸收光谱在红区和蓝区的吸收峰值;但它更大幅度地提高后者在低温(77K)下的PSⅡ相对荧光产量(F_(687))与PSⅠ相对荧光产量(F_(742))的比值,PSⅡ活性和PSⅡ原初光能转化效率。实验结果证明,更高的光强度可能有利于叶绿体形成更多可流动的LHC-Ⅱ和LHC-Ⅰ。     

Structure and Function of Chloroplast Membrane XVI. Comparative Studies on Some Photosynthetic Characteristics between Normal and Mutant Barleys

Some photosynthetic characteristics of mutant barley Chlorina f, were studied in comparison with that of normal variety. They were quite different in chlo- roplast membrane structures, pigment protein complexes, the content of electron transport components and photosynthetic functions. The absence of Chlb in mutant barley, as demonstrated by absorption and fluorescence excitation spectra, caused some defects of membrane structure and lose of the ability to regulate the distribution of excitation energy between PSII and PSⅠ. In comparison with the normal variety, the mutant barley contained much less chlorophyll per leaf area, but more P700, Cyt f and PQ on the chlorophyll basis. These differences surely affect their photochemical activities. As envisaged by fluorescence spectra, peripheral antenna of PSⅠ is absent in mutant barley membrane besides the lacking of Chl a/b-protein of PSⅡ. Fluorescence induction transient of mutant barley leaf did not show the typical time course of O→P→S→M→T. The coexistence of light harvesting Chl a/b-protein eomplex of PSⅡ and peripheral antenna of PSI and their cooperation with each other seem to be necessary for the occurence of typical fluorescence induction transient.     

Influences of Ce on the Formation of Chlorophyll-Protein Complexes in Chloroplasts of Cucumber Leaves

It has been proven that the Ce content of cucumber (Cucumis sativus L. ) leaves was enhanced with the increase of CeC13 concentration in Hoagland solution. The Chl a/b ratio of cucumber leaves in the control was the same as that in the treated plant, both being 3.67. However, under lower light intensity, the Chl a/b ratio in leaves of the contral was 2.72 whereas that of the treated leaves was 2.86. It showed that only under lower light intensity Ce could decrease the contents of chlorophyll b in leaves. The authors also evidenced that Ce was able to accelerate the formation of chlorophyll-protein complexes of PS Ⅰ and 110 kD polypeptide and decrease the light harvesting complex protein and 27 kD polypeptide.     

Comparative Study of Chlorophyll-Protein Complexes of Thylakoids of Bryopsis and Spinacia

properties, pigment compositions, Chl a/b ratios and apparent molecular weights of chlorophyll-protein complexes were compared between spinach and a marine green alga, Bryopsis corticulans. The results are as follows: 1. Ten chlorophyll-protein complexes were resolved from spinach thylakoid membranes solubilized by SDS in a final SDS/Chl weight ratio of 10:1, and subjected to SDS-PAGE with 11% resolution gel. CPIa 1–3 and CPI belonged to photosystem Ⅰ, and the rest to phorosystem Ⅱ. The maximum absorption of CPIa2, CPIas and CPI were all at 674nm, but that of CPIa1 at 670nm, and those of LHCII and D2 at 670 and 673nm, respectively. Chlorophyll ia PSⅡ was 63% of the total. In PSⅡ, most of chlorophyll was in LHCII which contained 86% of the chlorophyll in PSⅡ. In PSⅠ, chlorophyll in CPla was 72% of the total. Chlorophyll a was the main pigment in PSⅠ components which have Chl a/b ratio over 15. 2. Eight chlorophyll-protein complexes were isolated from B. corticulans with a SDS/Chi weight ratio of 8:1 and 8% resolution gel. The maximum absorption of CPIa, CPI, LHCII and D2 were respectively at 671nm, 673nm, 669nm and 664nm. PSⅡ contained 77% of the total chlorophyll. LHCII chlorophyll was 95% of the PSⅡ chlorophyll. CPI held 77% of PSⅠ chloro~ phyll. There was more chlorophyll b in Bryopsis complexes, especially in LHCI1 (Chl a/b< 0.8). The molecular weights of Bryopsis complexes were higher than those of the spinach complexes. Bryopsis LHCII contained siphoxanthin and siphothin, the marked pigments of Siphohales, as functional pigments. The above results revealed three points of difference between these two plants. Firstly, Chl a is the main pigment in spinach, whereas in Bryopsis the main pigments are Chl b and siphoxanthin. This is in accordance with the suggestion that plants may change their pigment composition to adapt light regime in the environment during evolution. Secondly, in Bryopsis, chlorophyll is concentrated in photosystem Ⅱ, but in spinach chlorophyll is shared evenly by two photosystems. Finally, CPI in Bryopsis contained the major part of chlorophyll in PSⅠ, yet in spinach CPIa is the superior.     

温州蜜柑叶片光系统反应中心光能分配的变化

为深入了解果树光化学反应中心光能分配的状况,以柑橘为试材,采用调制荧光法对叶片光系统在高光强和低光强下的状态转换进行了研究.结果表明, 光系统在100 μmol·m^-2·s^-1的低光强下,由于QA的还原使PQ库处于还原状态,导致光能由PSⅡ转向PSⅠ分配,光系统处于状态2;在1 000 μmol·m^-2·s^-1 的高光强下, PQ库无法得到电子而处于氧化状态,导致光能分配由PSⅠ转向PSⅡ,光系统处于状态1.叶片经磷酸酯酶抑制剂NaF处理后,光系统从高光强下状态2到状态1的转换受到抑制.高光强下过多的光能由PSⅠ向PSⅡ分配是导致PSⅡ光破坏的重要原因.     

The Chlorophyll-Protein Complexes Resolved from Ultrasonically Broken Thylakoid Memb-ranes of Blue-Green Algae

When the thylakoid membranes of blue-green algae were broken by ultrasonic vibrations and subjected to polyacrylamide gel electrophoresis at 4℃, six green zones were resolved. They were designated as CPIa, CPlb, CPI; CPal, CPa2, and FC. The absorption spectrum of CPI had a red maximum at 674 nm and a peak in the blue at 435 nm. It was identified as PS chlorophyll a-protein Complex, but was contaminated with minor PSⅡ which was implied by the appearance of fluorescence emission peak at 680 nm besides the main one at 725 nm at 77 K. The spectral properties of CPIa and CPlb were similar to that of CPl. The absorption spectra of CPa1 and CPa2 were similar, both having red maxima at 667 nm and peaks in the blue at 431.5 nm. Their fluorescence emission had the same peaks at 684 nm at 77 K indicating that they belonged to PSⅡ. It was recognized that CPal of 47 kD is the reaction center complex of photosystem Ⅱ and CPa2 of 40 kD is the internal antenna complex of photosystem Ⅱ. The spectral characteristics of the chlorophyll-protein complexes resolved by ultrasonic method were similar to those of the same complexes resolved by SDS solubilization, except the absorbance positions of CPa1 and CPa2 in the blue peak and the red one which shifted to blue about 3–5 nm. It was calculated that in thylakoid membranes of blue-green algae 40.93% chlorophyll was in PSⅠ, while 38.78% of chlorophyll in PSⅡ. The difference of chlorophyll contents between PSⅠ and PSⅡ was only 2.15%. Concerning the fact that minor PSⅡ compound remained in the part of PSⅠ zones, it might be concluded that the distribution of chlorophyll between PSⅠ and PSⅡ in blue-green algae was equal. This result was in agreement with the hypothesis that PSⅠ and PSⅡ operates in series in photosynthetic electron transport.     

低温光抑制恢复过程中黄瓜叶片PSⅡ活性及其电子传递对PSⅠ的影响

以“津春4号”黄瓜为试材,通过测定黄瓜叶片叶绿素荧光快速诱导动力学曲线和对820 nm光的吸收曲线,结合叶绿素荧光淬灭分析,研究低温光胁迫(4℃,200 μmol·m-2·s-1)6 h后,黄瓜叶片在常温(25℃)不同光强(0、15、200μmol·m-2·s-1)下PS Ⅰ和PS Ⅱ活性的恢复,以及恢复过程中PS Ⅰ与PS Ⅱ的相互作用.结果表明:低温光胁迫6h后,PS Ⅰ和PS Ⅱ发生不同程度的光抑制.在常温恢复阶段,PS Ⅱ活性快速恢复且对光强不敏感;PS Ⅰ活性在弱光下(15 μmol·m-2·s-1)快速恢复,在较强光(200 μmol·m-2·s-1)下恢复较慢.在低温光抑制恢复过程中,常温下PS Ⅱ活性恢复较快可能导致PS Ⅱ向PS Ⅰ的线性电子传递过快,进而抑制PS Ⅰ的活性恢复.因此,在进行黄瓜抗冷性育种时,不应该仅追求较高的PS Ⅱ抗性和较快的PS Ⅱ恢复速度,还应该注意两个光系统活性的协调.在生产中,应当在低温逆境发生及其之后较长一段时间内采取措施降低叶表面光照强度,以利于对植株光合机构的保护和光合活性的恢复.     

Studies on the Chlorophyll,protein Complexes and Polypeptides of Chloroplast Membrane of Cator Bean

The chlorophyll protien complexes separated from several plants were resolved by SDS-PAGE. It showed that the percentage (18%) of complex Ⅳ in total amount of chlorophyll of castor bean (Ricinus communis L.) was obviously higher than that ( 13% ) of snake gourd (Luffa cylindrka (L.) Roem) and the percentage (41%) of LHCP complex in total amount of chlorophyll of castor bean was lower than that (48%) of snake gourd. The light-induced variable fluorescence change of castor bean (Fv/Fo=2.6) was much higher than that of snake gourd (Fv/Fo = 1.08) and other plants. The photochemical activities of chloroplasts of castor bean were very high. Its oxygen evolution activity (H20 → DMBQ) was 575 μ moles O2·mg-1Chl·h-1, and the oxygen absorbtion activity of PSⅠ (DCIPH2 → WV) was 1274μ moles O2·mg-1Chl·h-1, the Chl/P700 ratio was 373, but those of snake gourd were 210, 148 and 751 respectively. There were distinct difference between the polypeptide pattern of castor bean and those of other plants. It was observed that 43, 47 KD polypeptide bands (polypeptides of PSⅡ) of castor bean were darker than those of other plants. From the results mentioned above, it was considered that the high photochemical activities possessed by castor bean chloroplasts were partly due to its small photosynthetic units, e.g. its LHCP/RCCHL ratio yas smaller than those of other plants.     

A Comparative Study on PSⅡ Light Harvesting Chlorophyll a/b Protein Complexes Between Spinach and Cucumber

PS Ⅱ light harvesting chlorophyll a/b protein complexes (LHC Ⅱ ) were isolated from chloroplast of spinach (Spinacia oleracea Mill. ) and cucumber (Cucumis sativus L. ). Comparative studies were made on the polymerized forms. Chl a/b ratio, spectral characteristics and polypeptide components of these two kinds of LHC Ⅱ. Experimental results showed that the LHC Ⅱ from spinach had a Chl a/b ratio of 1.33 and the LHC Ⅱ from cucumber had a Chl a/b ratio of 1.77. The spectral characteristics of the LHC Ⅱ from cucumber also indicated the enrichment of Chl b in this LHC Ⅱ . There was also obvious differences in the polypeptide components between these two kinds of LHC Ⅱ, the LHC Ⅱ of spinach contained a 27 kD and a 25 kD polypeptides, while the LHC Ⅱ of cucumber contained only a 27 kD polypeptide. This showed that the 25 kD polypeptide contained less Chl b. The analysis of the chlorophyll protein complexes showed that the monomer, dimer and trimer of the LHC Ⅱ of spinach were composed of two polypeptides, while all the polymerized forms of cucumber’s LHC Ⅱ were composed of one polypeptide.     

不同波长光照对罗汉果光合及生长影响

罗汉果试管苗在不同波长的LED(半导体)蓝(475±5nm)、黄(585±5nm)、红(660±5nm)及普通日光灯下培养,25d后观测发现,其外观的优劣依次为:蓝光>白光>红光>黄光;植株重量:蓝光>红光>黄光>白光;蓝光和白光下的植株叶大、色绿,植株矮壮,侧芽多;红光和黄光下的植株叶小、色黄绿,植株高、细、弯曲、节间长。测定罗汉果成熟叶片的吸收光谱,发现在波长380~500nm及660~680nm处有较强吸收。不同的光质下测定成熟叶片光合速率,大小依次为:红光>蓝光>白光>黄光。上述的各项试验表明,蓝光对罗汉果幼苗生长发育最好;红光和蓝光为成熟叶片光合作用的最佳光源。     

不同光质LED光源对草莓光合特性、产量及品质的影响

以‘妙香7号’草莓品种为材料,利用LED精量调制光源,设红光、蓝光、黄光、白光、红/蓝/黄(7/2/1)、红/蓝(7/2) 5个处理,以白光为对照,测定了草莓叶片的光合与荧光参数、色素含量、果实产量、品质和根系活力指标,研究 500 μmol·m^-2·s^-1光强下不同光质处理对草莓光合特性、果实产量及品质的影响.结果表明： 红光处理有利于提高草莓叶片的净光合速率与蒸腾速率,而蓝光有减弱作用;气孔导度与胞间CO₂浓度均以蓝光处理效果最为显著.叶绿素荧光参数(F_o、F_m、Φ_PSⅡ)均在红光处理下最大,而F_v/F_m、F_v/F_o、F_m/F_o均在红/蓝/黄处理下最大;红/蓝/黄处理下草莓色素含量、果实产量和根系活力均显著高于其他处理.红光处理的可溶性固形物和维生素C含量均最高,且与红/蓝/黄处理差异不显著;蓝光处理有利于提高可滴定酸和蛋白质含量,而红/蓝/黄处理的固酸比最大.红/蓝/黄处理最有利于增加光合色素含量,提高果实产量,促进部分品质改善.     

杂交酸模叶片线粒体交替氧化酶呼吸途径在光破坏防御中的作用

以杂交酸模(Rumex K-1)为试材,研究了不同光强下线粒体交替氧化酶呼吸途径(AOX途径)对酸模叶片光破坏的防御作用.结果表明:在200 μmol·m-2·s-1弱光下,用水杨基羟肟酸抑制AOX途径后,Rumex K-1叶片的PSⅡ实际光化学效率、光合线性电子传递速率以及光合放氧速率均显著下降,非还原性QB反应中心显著升高,加重了叶片的光抑制,而活性氧清除机制上调,避免了活性氧的过量积累,部分缓解了Rumex K-1叶片的光抑制;在800 μmol·m-2·s-1强光下,AOX途径受抑,导致Rumex K-1叶片发生严重的光抑制,而此时活性氧清除机制的上调不足以缓解活性氧过量的积累.无论在强光还是弱光下,AOX途径在Rumex K-1叶片的光破坏防御过程中都起着重要作用,而且在强光下,AOX途径对叶片的光破坏防御作用是叶绿体内其他光破坏防御途径所不能代替的.     

Effects of Cucumber Mosaic Virus Infection on Photosynthetic Activities of Tobacco Leaves and Chloroplasts

Changes in photosynthetic activities were studied with tobacco (Nicotiana tabacum L.) leaves and chloroplasts infected by cucumber mosaic virus (CMV) at the top, middle and bottom located leaves. Net photosynthetic rate was reduced at all three positioned leaves, with the maximum reduction occurring at the top leaves (31.9% of control). The infected chloroplasts showed a reduction in electron transport rates of the whole chain electron transport, photosystem Ⅱ (PSⅡ) and photosystem Ⅰ (PSⅠ). Since the decline in the whole chain electron transport (15.6% of control, H2O→MV) closely paralleled the decline in PSⅡ activity (20.9% of control, H2O→PBQ), the inhibition of the latter was probably responsible for the overall decrease. Chlorophyll a fluorescence measurements showed a variable reduced fluorescence yield (Fv/Fo) which indicated that PSⅡ was impaired and the CO2 assimilation was disturbed by CMV infection. Fluorescence emission spectra at 77 K indicated that energy distribution between PSⅡ and PSⅠ was affected. F686/F734 of infected leaves and chloroplasts increased and the greatest increase (331.1% of control ) was found in the top leaves. These data may conclude that the infection inhibited mainly the PSⅡ activity.     

Human nonvisual responses to simultaneous presentation of blue and red monochromatic light

Blue light sensitivity of melatonin suppression and subjective mood and alertness responses in humans is recognized as being melanopsin based. Observations that long-wavelength (red) light can potentiate responses to subsequent short-wavelength (blue) light have been attributed to the bistable nature of melanopsin whereby it forms stable associations with both 11-cis and all-trans isoforms of retinaldehyde and uses light to transition between these states. The current study examined the effect of concurrent administration of blue and red monochromatic light, as would occur in real-world white light, on acute melatonin suppression and subjective mood and alertness responses in humans. Young healthy men (18-35 years; n = 21) were studied in highly controlled laboratory sessions that included an individually timed 30-min light stimulus of blue (λ(max) 479 nm) or red (λ(max) 627 nm) monochromatic light at varying intensities (10(13)-10(14) photons/cm(2)/sec) presented, either alone or in combination, in a within-subject randomized design. Plasma melatonin levels and subjective mood and alertness were assessed at regular intervals relative to the light stimulus. Subjective alertness levels were elevated after light onset irrespective of light wavelength or irradiance. For melatonin suppression, a significant irradiance response was observed with blue light. Co-administration of red light, at any of the irradiances tested, did not significantly alter the response to blue light alone. Under the current experimental conditions, the primary determinant of the melatonin suppression response was the irradiance of blue 479 nm light, and this was unaffected by simultaneous red light administration.     

Photosynthetic characteristics of rice leaves grown under red light with or without supplemental blue light

In rice plants grown under red light supplemented with blue light (red/blue-light PPFD ratio was 4/1), photosynthetic rates per unit leaf area measured under white light at 1,600 and 250 micromol m-2) s-1 were higher than those in the plants grown under red light alone. The higher photosynthetic rates were associated with higher total N content of leaves, which was accompanied by larger amounts of key components of photosynthesis-limiting processes, including Rubisco, Cyt f, Chl and LHCII. These results suggested that the increase in total N content of leaves induced by supplemental blue light enhanced both light-saturated and light-limited photosynthesis.     

磷脂酰甘油对光系统Ⅱ放氧活性的影响

The dependence of oxygen evolution in PS Ⅱ from spinach Spinacia oleracea L. on the content of exogenous anionic phosphatidylglycerol (PG) at pH 6.0 was investigated through reconstitution experiment. It was found that there was a steady increase in oxygen evolution. With increasing PG/PS Ⅱ ratio up to a maximum at concentrations ranging from 10-22 mg PG/mg chlorophyll (Chl). Then, further addition of PG resulted in the inhibitions of oxygen evolution. With a PG/PS Ⅱ ratio of 40 mg PG/mg Chl, the oxygen-evolving activity of PS Ⅱ decreased to 40% of the untreated PS Ⅱ. It is suggested that a stimulation of oxygen evolution at a low PG/Chl ratio was resulted from the structural optimization of PS Ⅱ by PG while an inhibitory effect on oxygen evolution at higher values of this ratio was ascribed to the structural changes of extrinsic proteins of PS Ⅱ owing to osmotic pressure.     

Blue, red and blue plus red light control of chloroplast pigment and pigment-proteins in corn mesophyll cells: Irradiance level-quality interaction

Corn ( Zea mays L. cv. OP Golden Bantum) was grown under low irradiance blue, red or blue plus red light. Red was more effective than blue light for synthesis of Chl a, b and light-harvesting proteins (LHC-2) associated with photosystem 2(PS2). Blue light was slightly more effective for synthesis of light-harvesting proteins (LHC-1) associated with photosystem 1 (PS1), but below a fluence rate of 1 μmol m⁻² s⁻¹ the response to blue vs that to red depended on irradiance level. Blue light containing a small amount of red light was as effective as red light for Chl a and b synthesis, but no more effective than blue light for LHC-2 synthesis. Adding small amounts of blue light to red repressed the effect of red light on LHC-2 synthesis and produced irradiance response curves similar to those produced by blue alone for LHC-2 synthesis. This repression by blue light depended on the ratio of red to blue and the level of the blue light.     

Effects of Light on Chlorophyll Formation in Cultured Tobacco Cells I. Chlorophyll Accumulation and Phototransformation of Protochlorophyll(ide) in Callus Cells under Blue and Red light

A marked accumulation of chlorophyll was observed in calluscells of Nicotiana glutinosa when they were grown under bluelight, while under strong red light no chlorophyll accumulated.This blue light effect saturated at an intensity of about 500mW.m^–2. The effects of white, blue and red light on the transformationof protochlorophyll (ide) (Pchl) accumulated in dark-grown calluscells were studied by following the changes in the intensityof fluorescence emitted by Pchl and different forms of chlorophyll(ide) (Chi). Pchl with a fluorescence maximum at 633 nm (absorptionmaximum: 630 nm) decreased slowly, concomitant with an increasein Chl having a fluorescence maximum at 677 nm (absorption maximum:675 nm), which was subsequently transformed, independently oflight, to Chi with a fluorescence maximum at 683 nm (absorptionmaximum: 680 nm). Both blue and red light of low intensitieswere effective for the phototransformation, while red light,but not blue light, of high intensities caused significant destructionof Pchl. An action spectrum for this photodestruction showedthat the maximum destruction took place at 630 nm. White lightof high intensities was effective for the photoreduction withonly slight destruction of Pchl, suggesting that blue lightcounteracts the destructive effect of red light. At low temperatures,however, blue light as well as red light of low intensitiescaused photodestruction of Pchl. It was inferred that blue lightenhances a certain step or steps involved in the productionof a reductant required for the photoreduction of Pchl to Chl. (Received July 3, 1981; Accepted November 11, 1981)     

Effects of Water Stress on Energy Transduction in Chloroplasts

Water stress inhibited the photosynthetic O2 evolution rate of wheat leaves. It was shown that water stress decreased the electron transport rate, the activities of photophosphorylation and, coupling factor, and, the synthesis of ATP in chloroplasts. PS Ⅱ electron transport was more senstitive to water stress than PS Ⅰ. The reduction in photophosphorylation activity might be the results of reduction in electron transport rate and coupling factor activity, as well as the uncoupling effect of water stress on chloroplasts. The uncoupling effect could be due to the inhibition of light induced proton translocation in chloroplasts.     

Light-induced Damage of Photosystem Ⅱ Primary Electron Donor P680: a High Performance Liquid Chromatographic Analysis of Pigment Content in D1/D2/Cytochrome b559 Complex Under Photoinhibitory Conditions

By HPLC analytical method, the change of PS Ⅱ RC' s pigment content in the process of photodamage under strong illumination from spinach ( Spinacia oleracea Mill. ) was comparatively studied. The experimental results show that: (1) In authors' analytical conditions, (of which, [Chl] = 150 µg/mL, and the illumination strength was put at 2.3 ×10 6 mJ·m－2·s－1 ), 45 rain of illumination could cause almost the whole loss of A680 in the fourth derivative absorption spectra, while A670 decreased to about one half of its original intensity; the absorption maximum in red, concurrently, was shifted from 676 nm to 671 nm, representing the loss of more than 90% of the photochemical activities of the PS Il RC. (2) During the period of continuous illumination, the Chl concentration decreased in a 3-period style, which meant that the first [Chl] decreased to the 2/3 of its original amount from 20 min to 40 rain after illumination had started, then became stabilized up to about 60 min of illumination, there after a second decrease of [ Chl ] in another about 20 min until it reached about 30 % of the original level and remained unchanged from about 80 min on. The original pigment components of D1/D2/Cyt b559 was approximately as 6 Chl a:2 Pheo:2β-Car which are in support of authors' previous proposal about the minimum Chl/Pheo ratio of 4: 2 in PS Ⅱ RC’s pigment contents. (3) After about 40 min of illumination, a newly appeared elution peak was found between the Pheo andβ-Car peaks in HPLC profile, at the retention time of 7.2 min, a little later than that (6.9 rain) of Pheo molecules, the newly appeared elution peak was supposed to be a kind of accumulated and stable product of the PS II RC's photodamage process and very much possible the Pheo-like molecules.