大豆叶片发育中光合、结构及其与3种酶活性的关系

大豆叶片的光合速率、希尔反应活性、叶绿素含量、类囊体垛迭程度都随叶片扩展而增加、随老化而下降;希尔反应在老化时下降最早.次之为叶绿素含量和光合速率;类囊体膜随老化而解体.淀粉粒也减少以至消失,而脂质体球逐渐增加最后涨破叶绿体,叶片透性也增加.过氧化氢酶(CAT)活性随老化下降,超氧化物歧化酶(SOD)活性在发育旱期和老化后期较高.过氧化物酶(POD)活性则随发育及老化而不断升高.讨论了光合活性与结构及三个酶活性之间的关系.     

两个品种烟草叶片发育过程中几种光合参数变化的比较

比较烟草2个品种‘NC89’和‘JYH’叶片发育过程中几个光合参数变化的结果表明,烟草叶片发育过程中光合速率变化表现为上升期、高值持续期（APD）和速降期,叶绿素含量变化经历上升期、相对稳定期（RSP）和速降期。光合功能衰退过程中,核酮糖．1,5-二磷酸羧化酶（RuBPCase）活性比电子传递活性下降快。可逆衰退阶段的2个品种类囊体膜多肽组分和‘NC89’的核酮糖-1,5-二磷酸羧化酶加氧酶（Rubisco）大亚基基本上无变化;不可逆衰退阶段的2个品种类囊体膜多肽组分、Rubisco大小亚基均快速降解,尤其是光系统Ⅱ（PSⅡ）复合体和Rubisco小亚基。‘JYH’的叶龄为10-40d的叶中各光合参数与‘NC89’的差别不大,但‘JYH’的光合功能期短,光合功能衰退过程中光合电子传递与碳同化失衡较严重,光合功能衰退比‘NC89’早而迅速。     

Changes Related to Salt Tolerance in Thylakoid Membranes of Photoautotrophically Cultured Green Tobacco Cells

A line of cultured tobacco cells (Nicotiana tabacum cv. SamsunNN) was established that was able to grow photoautotrophicallyin a medium that contained 0.2 M NaCl or in a medium withoutNaCl. Thylakoid membranes of the NaCl-adapted cells had higheroxygen-evolving activities, on the basis of chlorophyll, thanthose of unadapted cells. Furthermore, the oxygen-evolving activitiesof thylakoid membranes from NaCl-adapted cells were more tolerantto high concentrations of NaCl than those from unadapted cells. Glycinebetaine at 1 M protected the oxygen-evolving activityof thylakoid membranes from unadapted cells but not that fromadapted cells. Examination of the dissociation of 23-kDa and33-kDa polypeptides from the water-splitting complex of photosystemII at high concentrations of NaCl indicated that the affinitywith which the 23-kDa polypeptide was bound to thylakoid membranesof salt-adapted cells had been altered. (Received March 22, 1993; Accepted November 15, 1993)     

Photoautotrophic Culture of Undifferentiated Cells and Shoot-Forming Cultures of Digitalis purpurea L.

Undifferentiated cells and shoot-forming cultures of Digitalispurpurea L. were grown photoautotrophically under 1% CO₂. During3 weeks of culture, the undifferentiated cells multiplied 3-foldand the shoot-forming cultures 2-fold on a fresh weight basis.The chlorophyll content, ribulose 1,5-bisphosphate carboxylaseactivity, Hill reaction activity of the isolated chloroplastsand photosynthetic O₂ evolution of the photoautotrophicallygrown cultures were somewhat higher than the values of the correspondingphotomixotrophic cultures. The digitoxin contents, however,were not improved by photoautotrophic culture. (Received November 9, 1983; Accepted June 11, 1984)     

Photosynthesis and nitrogen relationships in leaves of C3 plants

Summary The photosynthetic capacity of leaves is related to the nitrogen content primarily bacause the proteins of the Calvin cycle and thylakoids represent the majority of leaf nitrogen. To a first approximation, thylakoid nitrogen is proportional to the chlorophyll content (50 mol thylakoid N mol^-1 Chl). Within species there are strong linear relationships between nitrogen and both RuBP carboxylase and chlorophyll. With increasing nitrogen per unit leaf area, the proportion of total leaf nitrogen in the thylakoids remains the same while the proportion in soluble protein increases. In many species, growth under lower irradiance greatly increases the partitioning of nitrogen into chlorophyll and the thylakoids, while the electron transport capacity per unit of chlorophyll declines. If growth irradiance influences the relationship between photosynthetic capacity and nitrogen content, predicting nitrogen distribution between leaves in a canopy becomes more complicated. When both photosynthetic capacity and leaf nitrogen content are expressed on the basis of leaf area, considerable variation in the photosynthetic capacity for a given leaf nitrogen content is found between species. The variation reflects different strategies of nitrogen partitioning, the electron transport capacity per unit of chlorophyll and the specific activity of RuBP carboxylase. Survival in certain environments clearly does not require maximising photosynthetic capacity for a given leaf nitrogen content. Species that flourish in the shade partition relatively more nitrogen into the thylakoids, although this is associated with lower photosynthetic capacity per unit of nitrogen.     

Changes in Chlorophyll Content and Organization During Senescence of the Primary Leaves of Phaseolus vulgaris L. in Relation to Photosynthetic Electron Transport

A large decrease was observed in the chlorophyll content ofthe primary leaves of Phaseolus vulgaris during senescence.Chloroplasts isolated from mature and senescent leaves gavevery similar light saturation curves for electron transportreactions involving either PS I or PS II, indicating that theaverage number of chlorophyll molecules associated with eachreaction centre did not change during senescence. It is concludedthat the reaction centres ceased to function at the same timeas, or perhaps before, their antenna chlorophylls were lostfrom the thylakoid membrane, and that the percentage decreasein the number of functional reaction centres per leaf was atleast as great as the percentage decrease in the leaf chlorophyllcontent. The chlorophyll-protein composition of thylakoid membrane preparationswas examined by electrophoresis of samples treated with sodiumdodecyl sulphate. In older leaves a smaller proportion of thechlorophyll applied to polyacrylamide gels was associated withthe P700- chlorophyll a-protein complex. There was also a declinein emission at 734 nm in the 77 °K fluorescence spectrumof intact leaf tissue during senescence. These results indicatethat older leaves contained a smaller proportion of chlorophyllsassociated with PS I, and this is consistent with the decreaseobserved in the leaf chlorophyll a/b ratio during senescence.The effect of these changes in chlorophyll content on the capacityof the chloroplast to carry out photosynthetic electron transportis discussed.     

Effects of Polyploidy on Photosynthetic Rates, Photosynthetic Enzymes, Contents of DNA, Chlorophyll, and Sizes and Numbers of Photosynthetic Cells in the C(4) Dicot Atriplex confertifolia

Photosynthetic rates, chlorophyll content, and activities of several photosynthetic enzymes were determined per cell, per unit DNA, and per unit leaf area in five ploidal levels of the C₄ dicot Atriplex confertifolia. Volumes of bundle sheath and mesophyll protoplasts were measured in enzymatic digestions of leaf tissue. Photosynthetic rates per cell, contents of DNA per cell, and activities of the bundle sheath enzymes ribulose 1,5-bisphosphate carboxylase (RuBPC) and NAD-malic enzyme per cell were correlated with ploidal level at 99% or 95% confidence levels, and the results suggested a near proportional relationship between gene dosage and gene products. There was also a high correlation between volume of mesophyll and bundle sheath cells and the ploidal level. Contents of DNA per cell, activity of RuBPC per cell, and volumes of cells were correlated with photosynthetic rate per cell at the 95% confidence level. The mesophyll cells did not respond to changes in ploidy like the bundle sheath cells. In the mesophyll cells the chlorophyll content per cell was constant at different ploidal levels, there was less increase in cell volume than in bundle sheath cells with an increase in ploidy, and there was not a significant correlation (at 95% level) of phosphoenolpyruvate carboxylase activity or content and pyruvate,Pi dikinase activity with increase in ploidy. The number of photosynthetic cells per unit leaf area progressively decreased with increasing ploidy from diploid to hexaploid, but thereafter remained constant in octaploid and decaploid plants. Numbers of cells per leaf area were not correlated with cell volumes. The mean photosynthetic rates per unit leaf area were lowest in the diploid, similar in 4×, 6×, and 8×, and highest in the decaploid. The photosynthetic rate per leaf area was highly correlated with the DNA content per leaf area.     

The photoautotrophic culture of chlorophyllous cells

Photosynthesis in chlorophyllous cells in heterotrophic cultureswas investigated. Chlorophyllous cells from the amur cork-tree,scotch broom and tobacco, all of which had relatively high chlorophyllcontents (70 to 120 µg/g fresh weight) were selected throughoutcallus induction and cell subculture. When cultured under variouslight intensities, growth was stimulated by increases in lightintensity. This stimulation depended on the chlorophyll contentsof the cells. It disappeared on the addition of photosynthesisinhibitors (DCMU or 2-chloro-4,6-bis(ethylamino)-s-triazine).These phenomena indicate that photosynthesis accounted for athird to a half of cell growth under strong illumination. These heterotrophic cultures were then developed as autotrophiccultures. When these chlorophyllous cells were cultured withaeration using CO₂-enriched air in the light condition, thescotch broom and tobacco chlorophyllous cells grew photoautotrophically.Nearly the same amount of growth as with 3% sucrose in the darkwas observed in an autotrophic culture with aeration using aircontaining 1% CO₂. The green tobacco cells have been subculturedautotrophically for about one year. (Received November 28, 1977; )     

Photosynthetic properties of two different soybean suspension cultures

The photosynthetic properties of two commonly used suspension cultured lines, embryogenic and photoautotrophic (PA, SB-1 line) cells of soybean [Glycine max (L.) Merr.] were characterized. We found that compared to the dark green PA cells, the light green embryogenic cells contained fewer and smaller plastids with less-developed thylakoid membranes. The embryogenic cells also contained much lower contents of both chlorophyll and the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) protein, an undetectable level of Rubisco small subunit protein, and a very low rate of photosynthesis. While the DNA contents of the nuclear genomes were similar in these two types of cultured cells, the embryogenic cells possessed a markedly lower content of plastid DNA. The 18-year-old PA suspension culture, SB-1, continues to evolve with higher Rubisco and plastid DNA contents than leaves, and with small decreases in nuclear DNA content that appears to mimic changes in chromosome numbers. These findings may prove useful in the application of plastid transformation, particularly when non-leaf or non-green tissues must be used as targets for transformation and plant regeneration.     

Photoautotrophic cell suspension cultures of periwinkle (Catharanthus roseus (L.) G. Don): Transition from heterotrophic to photoautotrophic growth

Chlorophyllous, heterotrophic periwinkle (Catharanthus roseus (L.) G. Don) cells were capable of sustained photoautotrophic growth in sugar-free B5 medium containing naphthaleneacetic acid and kinetin when provided with a CO₂-enriched atmosphere. An increase in cell fresh weight, first observed approximately 2 weeks after transfer from heterotrophic to photoautotrophic conditions, coincided with the development of maximum chlorophyll content and photosynthetic activity. Electron micrographs revealed that chloroplasts of cells cultured photoautotrophically in continuous light contained large starch granules and exhibited a less extensive thylakoid system than did periwinkle mesophyll chloroplasts. Photoautotrophic cells did not accumulate vindoline or dimeric alkaloids.Abbreviations Chl chlorophyll - dry wt dry weight - fr wt fresh weight - 2,4-D 2,4-dichlorophenoxyacetic acid - NAA naphthaleneacetic acid     

Effect of transient accumulation of anthocyanin on leaf development and photoprotection of Fagopyrum dibotrys mutant

Changes in pigments contents, leaf area, leaf dry mass per unit area (LMA), photosynthetic rate and chlorophyll a fluorescence were investigated in developing leaves of Fagopyrum dibotrys Hara. mutant. Anthocyanins transiently accumulate below the upper epidermis during leaf ontogeny of this mutant. Red leaves possessed lower Chl content, LMA, photosynthetic rate and apparent carboxylation efficiency than green leaves. However, content of anthocyanins declined and above mentioned parameters increased during further leaf development. In both red and green leaves, chronic photoinhibition did not take place according to variable to maximum chlorophyll fluorescence ratio (F_v/F_m). Red leaves had higher non-photochemical quenching (NPQ) and higher PS 2 efficiency.     

Growth of Photoheterotrophic Cells of Peanut (Arachis hypogaea L.) in Still Nutrient Medium

Cell suspension cultures were established from the callus proliferation of leaf explants of 10- to 12-day-old seedlings of the peanut (Arachis hypogaea L. var. TMV-3). The cells could be cultivated in both agitated and still media, the latter promoting more of chlorophyll (Chl) synthesis. High Chl content (210-240 micrograms Chl per gram fresh weight), yield of free and pipetable cells, presence of all the pigments in the same ratio as that of the leaf tissue, and high rates of O₂ evolution (140-170 micromoles O₂ per milligram Chl per hour) were some of the desirable features of the still-grown cell cultures. However, considerable variations with regard to the above characters were observed between the cell cultures of different varieties of the peanut.

O₂ evolution by the cultured cells was dependent on exogenous supply of HCO₃⁻. A well-developed photosynthetic apparatus as evidenced from photosystem I and photosystem II activities of the isolated chloroplasts and variable fluorescence measurements with the cell cultures was further documented by electron microscopic evidence of distinct granal stackings in chloroplasts and sodium dodecyl sulfate-polyacrylamide gel separation of thylakoid membranes into P700 Chl a protein complex and light-harvesting Chl a/b complex. Evidence is presented for the relative increase in the Chl associated with P700 Chl a protein complex in contrast to the light-harvesting Chl a/b complex in the cultured cells as compared to intact leaf.

     

金叶连翘叶片色素含量和解剖结构研究

金叶连翘不同冠层的成熟叶片呈现为不同颜色。以朝鲜连翘深绿色叶为对照,观察金叶连翘冠层上、中、下位叶色,测定其叶片大小和叶绿素a、叶绿素b、总叶绿素及类胡萝卜素含量,同时观察分析叶片横切面解剖结构,旨在阐明叶片色素含量和解剖结构对叶色的影响。研究表明:上层黄色、中层黄绿色、下层浅绿色,黄、黄绿、浅绿色叶总叶绿素含量分别是对照组的0.51%、4.44%和66.47%,均极显著低于对照(P <0.01),但黄绿叶的叶绿素a/b比值显著升高(P <0.05),黄、黄绿叶的总叶绿素/类胡萝卜素比值极显著降低(P <0.01)。黄、黄绿叶的叶绿体发育停滞于单片层时期,类囊体分化程度低,浅绿叶类囊基粒片层肿胀;黄叶细胞器降解,栅栏组织细胞形状难以辨别,黄绿叶上表皮细胞凸起。金叶连翘属于总叶绿素及叶绿素b合成减少型突变体,表现为叶绿素严重缺失,类胡萝卜素相对含量升高;其叶绿体发育停滞,类囊体结构异常,是金叶连翘叶片呈现不同颜色的主要因素,与其叶片解剖显微结构无关。     

Photosynthetic Properties of Green Barley Leaves after Treatment with Pyridazinone Herbicides--Comparison with the Effects of Diuron

Photosynthetic characteristics of detached green barley leavesafter 72 h of treatment with 0·2 mol m^–3 of thepyridazinone herbicides SAN 6706, SAN 9785 and SAN 9789 werestudied. For comparison, the effects of 0·01 mol m^–3diuron were also investigated. Pyridazinone herbicides causedonly a slight reduction of the total carotene content of thebarley leaves. The total chlorophyll content, as well as thelinolenic to linoleic acid ratio of chloroplast glycerolipids,however, remained unchanged. Diuron treatment caused total inhibitionof electron transport, as revealed by fast fluorescence inductionof leaves and the Hill reaction activity of chloroplasts. The¹⁴CO₂-nxation by the leaves and the light-induced fluorescencequenching were also completely inhibited in vivo by diuron.Pyridazinone herbicides left 20–40% of the ¹⁴CO₂-fixationfound in the control, in spite of the fact that their fast fluorescenceinduction tracings showed inhibition in the electron transport.Chloroplasts isolated from the leaves treated with pyridazinoneswere found to be highly active in mediating the ferricyanide-dependentHill reaction. In order to test the ability of pyridazinonesto inhibit photosynthetic electron transport in vivo, their‘prompt’ effect on fluorescence was also investigated.It is concluded that pyridazinone herbicides can readily andrapidly enter the chloroplasts and inhibit the photosyntheticelectron transport in vivo. The differences between the long-termeffects of pyridazinones and those of diuron suggest differencesin the inhibitory effectiveness on the various photosyntheticparameters between the two herbicide groups. It is suggestedthat pyridazinones can leave the chloroplasts during isolationowing to the loose binding onto the thylakoid membranes. Key words: Pyridazinone herbicides, electron transport, fluorescence induction     

Chloroplast Nucleoids during Greening of Cyanidium caldarium M-8 Type

Cyanidium caldarium M-8 type grown in the dark was illuminatedfor 3 days, and changes of its cell and cell organelle structuresand of photosynthetic activity were observed quantitatively.Dark grown (DG) cells showed no photosynthetic activity andno phycocyanin. During 3 day illumination they fully recoveredtheir photosynthetic activities as measured by Hill reaction,and also synthesized chlorophyll a and phycocyanins. Sizes ofcell, cell nucleus, chloroplast and its nucleoid observed byfluorescence microscopy after staining with DAPI increased simultaneouslyupon illumination. The chloroplast and its ring shaped nucleoidsizes increased especially rapidly, concomitant with the recoveryof Hill activity. In fully recovered cells after 3 days, a goodcorrelation was found among the sizes of cells, chloroplastsand chloroplast nucleoids. ( Revision received June 28, 1986. Accepted December 23, 1986)     

Heterogeneity of the maize leaf blade in photosynthetic characteristics,respiration, mineral nutrient contents,and growth substances

N, P, K, Ca, and Mg contents, chlorophyll content, gibberellin-like substance content, photosynthetic and respiration rates, Hill reaction activity, and specific leaf area of different parts of the leaf blade of maize (Zea mays L.) were determined. Parts with highest values of the determined components and processes were marked in the longitudinal and transverse profiles of the leaf blade. The established gradients of substance contents and of the functional activity were related to the growth stage of the leaf.     

Photosynthetic apparatus of pea thylakoid membranes : response to growth light intensity

We investigated the effect of growth light intensity on the photosynthetic apparatus of pea (Pisum sativum) thylakoid membranes. Plants were grown either in a growth chamber at light intensities that ranged from 8 to 1050 microeinsteins per square meter per second, or outside under natural sunlight. In thylakoid membranes we determined: the amounts of active and inactive photosystem II, photosystem I, cytochrome b/f, and high potential cytochrome b₅₅₉, the rate of uncoupled electron transport, and the ratio of chlorophyll a to b. In leaves we determined: the amounts of the photosynthetic components per leaf area, the fresh weight per leaf area, the rate of electron transport, and the light compensation point. To minimize factors other than growth light intensity that may alter the photosynthetic apparatus, we focused on peas grown above the light compensation point (20-40 microeinsteins per square meter per second), and harvested only the unshaded leaves at the top of the plant. The maximum difference in the concentrations of the photosynthetic components was about 30% in thylakoids isolated from plants grown over a 10-fold range in light intensity, 100 to 1050 microeinsteins per square meter per second. Plants grown under natural sunlight were virtually indistinguishable from plants grown in growth chambers at the higher light intensities. On a leaf area basis, over the same growth light regime, the maximum difference in the concentration of the photosynthetic components was also about 30%. For peas grown at 1050 microeinsteins per square meter per second we found the concentrations of active photosystem II, photosystem I, and cytochrome b/f were about 2.1 millimoles per mol chlorophyll. There were an additional 20 to 33% of photosystem II complexes that were inactive. Over 90% of the heme-containing cytochrome f detected in the thylakoid membranes was active in linear electron transport. Based on these data, we do not find convincing evidence that the stoichiometries of the electron transport components in the thylakoid membrane, the size of the light-harvesting system serving the reaction centers, or the concentration of the photosynthetic components per leaf area, are regulated in response to different growth light intensities. The concept that emerges from this work is of a relatively fixed photosynthetic apparatus in thylakoid membranes of peas grown above the light compensation point.     

Development of Photosynthetic Structure and Function during Light-Induced Greening in Photomixotrophic Cells of Arachis hypogaea L.

The synthesis of chlorophyll and development of photochemicalactivities were complete within 70–80 h in greening leaves,whereas these processes continued for 8 days with an initiallag of 8 h for pigment synthesis in greening Arachis hypogaeaL cells. The activity of photosystem I in cultured Arachis cellswas detected earlier (24–36 h after illumination) thanthat of photosystem II (42–54 h after illumination) andthe development of the latter coincided with the synthesis ofa 46,000 dalton polypeptide of the thylakoid membranes. Experimentalstudies with cultured cells have the advantage in that the temporalsequence of the assembly of membrane components and associatedfunctions are determined easily because of longer developmentalperiod of chloroplast. (Received January 29, 1982; Accepted April 13, 1983)     

Photosynthetic characterization at different senescence stages in an early senescence mutant of rice <Emphasis Type="Italic">Oryza sativa</Emphasis> L.

An early senescence (es) mutant of rice Oryza sativa L. with progressing death of most of leaves before heading stage was identified in the field in Hainan province. After tillering stage, the brown striations were found in the base of green leaves randomly, and then expanded to whole leaves. No fungi, bacteria, and viruses were detected in the brown striations suggesting that it was a genetic mutant. The ultrastructure of leaf cells at the site of brown striations showed breakdown of chloroplast thylakoid membrane structures and other organelles, and condensation of the cytoplasm at severe senescence stage. The photosynthetic activity and chlorophyll (Chl) contents decreased irreversibly along with leaf senescence process.     

烤烟冠层光谱参数与叶片叶绿素含量的相关分析

为了明确烤烟冠层光谱参数与叶片叶绿素含量的相关性,测定了不同氮肥施用量条件下烤烟冠层光谱特征和烤烟鲜烟叶片叶绿素a(Chl-a)、叶绿素b(Chl-b)、类胡萝卜素(Cars)含量,并对光谱参数与叶绿素含量进行了相关分析和回归分析。结果表明:随着氮肥施用量增加,团棵期和旺长期鲜烟叶片的Chl-a、Chl-b和Cars含量均增加,可见光波段反射率降低、近红外波段反射率增加;而打顶期叶片的3种色素含量和光谱特征的变化规律不明显。可见光460～670nm范围内,460nm反射率与叶片叶绿素含量呈显著正相关,其他波段反射率与叶片叶绿素的含量呈显著负相关;近红外780～1260nm范围内,所有波段与叶片叶绿素含量的都呈显著正相关,1480nm反射率与叶片叶绿素含量呈显著负相关。反映Chl-a、Chl-b、Cars含量与光谱参数——比值植被指数(ratio vegetation index,RVI)定量关系的最佳回归方程分别为幂函数、幂函数和指数函数:Chl-a=0.250RVI(730,550)1.511,Chl-b=0.049RVI(730,550)1.841,Cars=0.0998e0.379RVI(730,550)。