Levels of Carboxyarabinitol 1-Phosphate and Related Photosynthetic Components during Leaf Development in Phaseolus vulgaris

The influence of leaf development on the levels of carboxyarabinitol1-phosphate (CA1P), carboxyarabinitol (CA), CA1P phosphataseactivity, ribulose bisphosphate carboxylase (rubisco) activity,photosynthesis, and rubisco catalytic sites was examined inPhaseolus vulgaris. Leaves were sampled at mid-day or after15 h dark over a 3 week growth period. Mid-day initial rubiscoactivities were comparable to net photosynthetic rates, reaching245 µmol (mg Chl)^-1 h^-1 at 67–100% full size (26–30µmolm^-2 s^-1). CA1P and CA were present at substantial levels inleaves of all ages (light and dark-treated, respectively), increasingby similar amounts throughout expansion. Total rubisco catalyticsites increased 2.4-fold to 58 nmol (mg Chl)^-1 during leaf growthto 66% full size, remaining constant with further expansion.CA1P phosphatase activity was particularly low in the youngestleaves, and increased 14-fold during leaf expansion. CA1P content of dark bean leaves (nmol per mg Chl) was alwaysin excess of total rubisco catalytic sites throughout development,but decreased from 2.2-fold (mol CA1P per mol sites) in theyoungest leaves to 1.4-fold at maturation. The number of rubiscocatalytic sites bound to CA1P in the dark was measured in differentaged leaves after extracting leaves with 25 mM ammonium sulfate,which stabilizes the in vivo level of CA1P bound to rubisco.These measurements demonstrated that in the youngest leavesrelatively much less CA1P was bound to rubisco catalytic sitesin the dark. This was in contrast to what occurred in dark-treatedolder leaves, in which a large proportion of catalytic siteswere bound with CA1P. We suggest that in very young bean leaveseither rubisco has a reduced affinity for CA1P, or much of theCA1P in dark leaves may be bound to another, unidentified cellularcomponent(s). (Received April 25, 1995; Accepted June 30, 1995)     

Leaf Properties Related to the Photosynthetic Response to Drought in Upland and Lowland Rice Varieties

Four upland and two lowland varieties were grown on floodedand dry soil in pots in a glasshouse. Photosynthetic rate (P),transpiration rate (T), and water content (W) of the secondexpanded leaf from the top of the main stem were measured undercontrolled aeration and illumination in a leaf chamber in thelaboratory, together with leaf area (La), dry matter content(DM), nitrogen content (N), stomatal frequency (Sf), and totalvessel cross-sectional area at the base of the leaf blade (Va).P/La was positively related to T/La and Sf/La among six varietieswhen they were grown on flooded soil. IR 8, a semidwarf indicalowland variety, showed the highest P/La with the highest Sf/Laand T/La. When grown on dry soil P/La was positively correlatedwith W/DM, the latter being negatively related to T/Va. Twoupland varieties, African Moroberekan and Brazilian IAC 1246,showed the highest P/La on dry soil, keeping a higher W/DM witha lower T/La and a lower T/Va. Daytime leaf diffusive conductance(l/r_L) and leaf water potential (_L) measured on the same orthe same stage leaf in the glasshouse were positively correlatedwith the W/DM measured in the laboratory among varieties grownon dry soil. Simultaneous observation of P, T and W in the laboratoryindicated nonstomatal reduction in P/La due to leaf water deficitin sensitive varieties, although these varieties also showeda markedly lower daytime l/r_L in the glasshouse as comparedwith resistant varieties. Oryza sativa L., rice, drought resistance, photosynthesis, transpiration, water deficit, stomatal frequency, vessel size     

Photosynthetic CO2 Uptake and Whole Plant Growth as Related to Plant Water Relations

Morphological features of arid region plant life forms are described and interpreted as adaptations to drought although this cannot be easily quantified. Functional adaptations, however, can be measured, and using the annual crop plant Vigna unguiculata (L.) Walp. responses to drought are described at the leaf and the whole plant level. In the first step of this analysis theoretical criteria are developed to define optimal water use. In the second step experimental data are used to test to what extent Vigna follows a theoretically optimal regulation of water and carbon relations. The analysis indicates that the ecological adaptation of regulatory processes may be quantified at a functional level.     

Tissue Partitioning During Leaf Development in Ornamentally-grown Frithia pulchra (Mesembryanthemaceae), a 'Window Plant'

Young (i.e. 5-mm long) leaves of the window-plant Frithia pulchra(Mesembryanthemaceae) allocate approx, 21 % of their volumeto epidermis, 49 % to chlorenchyma, and 29 % to window tissue.By the time leaves are 25 mm long, the relative volumes of epidermisand chlorenchyma decrease to approx, 7 and 27 % respectively.During the same period, the relative volume of window tissueincreases from 29 to 66 %. The relative volumes of epidermis,window, and chlorenchyma tissues do not change as leaf lengthincreases from 25 to 57 mm. These results indicate that earlystages of leaf development in F. pulchra involve preferentialreallocations of volume to different tissues, whereas laterstages of leaf development involve uniform expansion of allof the leaf's tissues (i.e. the relative volumes of tissuesdo not change). The relative volumes of epidermis and windoware always largest in the lower third of a leaf. The relativevolume of chlorenchyma is largest in the upper third of youngleaves but becomes constant in the upper two thirds of leavesduring later stages of development. These results, indicatingthat leaves and tissues of F. pulchra are asymmetric and developpolarly, are discussed relative to corresponding studies ofcellular size and leaf structure. Frithia pulchra, leaf development, Mesembryanthemaceae, stereology, window plant     

Influence of GA3 and 4-PU-30 on Leaf Protein Composition, Photosynthetic Activity, and Growth of Maize Seedlings

The effects of gibberellic acid (GA3) and N1-(2-chloro-4-pyridyl)-N2 phenylurea (4-PU-30) on maize seedling growth, photosynthetic parameters, and leaf protein composition were investigated. The agents used alone or in combination increased leaf growth and photosynthetic rate of the seedlings. Chlorophyll and total nitrogen contents in leaves as well as the quantity of individual protein fractions increased simultaneously. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of soluble proteins (albumins and globulins) revealed quantitative differences between 4-PU-30-treated plants and the other experimental variants. They differed in polypeptide composition associated with changes in soluble proteins and amino acids. However, GA3 did not induce similar changes in polypeptide composition of soluble proteins. This revised version was published online in July 2006 with corrections to the Cover Date.     

燕麦植株生长及叶片生理活性对土壤镉胁迫的响应

该研究以燕麦品种‘燕科2号’(籽粒镉积累量高,Yh)和‘200919 7 1’(籽粒镉积累量低,Yl)为材料,采用盆栽试验,在土壤Cd胁迫条件下测定两种类型燕麦植株生长、叶片光合生理参数及抗氧化酶活性的变化,探讨两品种对Cd胁迫的响应差异。结果表明：(1)Cd胁迫条件下,燕麦品种Yh和Yl植株生长、气体交换参数及叶绿素荧光参数均受到抑制,并以单株干重、叶片净光合速率(P_n)、光化学淬灭系数(qP)表现最为突出,Yh的降幅分别为38.2%、35.0%、14.7%,Yl降幅分别为40.8%、57.1%、27.3%。(2)镉胁迫均诱导增强了两个类型燕麦品种叶片抗氧化酶活性,尤其是SOD活性得到显著增强,Yh和Yl的增幅分别为41.9%和44.9%; Cd胁迫也显著提高了MDA含量,Yh和Yl的增幅分别达到22.2%和18.1%。研究发现,在Cd胁迫条件下,与低Cd积累燕麦品种相比,高Cd积累燕麦品种具有较高的生物量和抗氧化酶活性,以及较强的净光合速率和优异的叶绿素荧光特性,从而表现出较强的耐Cd性。     

Changes in Photosynthetic Activity and Related Processes Following Decapitation in Mulberry Trees

Physiological responses to decapitation, in combination with bud removal or bud retention, were followed for 45 days in mature leaves of potted mulberry trees (single shoot with 24 to 28 leaves) held in a greenhouse. Mature leaves, whose photosynthetic activity had already attained a maximum, initially increased and subsequently maintained their rates of gas exchange after decapitation. Equivalent leaves on intact trees showed a gradual decline in photosynthesis together with other changes generally associated with early senescence viz. loss of chlorophyll, increased starch, and accumulation of one category of cytokinin-like material presumed to be a glucose ester. Maintenance of physiological activity following decapitation, especially when combined with bud removal, was associated with greater chlorophyll content, mesophyll cell enlargement (palisade cells appeared more elongate), lower starch, and alteration in foliar levels of cytokinin-like substances. Internal constraints on CO₂ assimilation, i.e. residual resistance (rr), rather than stomatal factors, appeared to be the major influence on gas exchange. The higher photosynthetic activity of leaves on decapitated trees relative to control trees of the same age was attributed to lower r, but was also associated with higher chlorophyll content (leaf area basis) so that CO₂ assimilated per unit chlorophyll was not substantially altered by treatment.     

四种热带雨林树种光合和形态解剖特征对不同生长光强的适应

研究了西双版纳热带雨林2种喜光树种中平树(Macaranga denticulata)、倒樱木(Pnravallaris macrophylla)和2种耐荫树种云南肉豆蔻(Myristica yunnanensis)、金丝李(Garcinia paucinervis)幼苗叶片光合和形态解剖特征对3种不同生长光强(5％、25%和50％相对光强)的适应。研究结果表明,与强光下相比,弱光下生长的4种植物最大净光合速率、光饱和点、光补偿点、暗呼吸速率、叶绿素a／b、叶片和栅栏组织厚度、气孔密度和比叶重都降低,而海绵组织／栅栏组织和叶绿素含量升高。在相同光强下,与2种耐荫树种相比,2种喜光树种有较大的最大净光合速率、暗呼吸速率、气孔密度和较低的叶绿素含量。在不同光强下,4种植物均表现出了对光适应有利的生理和形态解剖可塑性,而喜光树种比耐荫树种有较大的生理和形态可塑性,表明喜光树种具有比耐荫树种对强光有更强的适应能力。4种植物的生理指标的可塑性均大于叶片解剖结构的可塑性。     

Metabolic Activity of Isolated Leaf Cells of Phaseolus vulgaris in Relation to Leaf Development

Mesophyll cells were isolated from primary leaves of 5- to 21-day Phaseolus vulgaris plants. The rate of photosynthesis and respiration, and RNA, protein, and lipid synthesis was determined for these cells. Appropriate ¹⁴C substrates and product purification procedures were used for each process prior to liquid scintillation counting. The size of the leaves increased about 5-fold between days 5 and 11, and then remained relatively constant. The greatest increase in size occurred between days 5 and 6. The age of the leaf from which the cells were isolated had a pronounced effect on the rate of all of these processes. The largest changes occurred during the period of leaf expansion (days 5-11). Initially the rate of RNA, protein, and lipid synthesis increased rapidly, maintained a maximum rate for only 1 day (day 6 or day 7), and then declined. The rate of photosynthesis increased more slowly reaching a maximum at day 9, remained relatively constant until day 15, and then declined. The rate of respiration decreased during the first 4 days to low level which was maintained throughout the experiment. The time course patterns of these biochemical processes in isolated cells were similar to those which have been reported for intact leaves. It seems that isolation of leaf cells does not modify their metabolic activity.     

The Dynamics of Leaf Growth and Photosynthetic Capacity in Capsicum frutescens L.

In Capsicum frutescens L. cv. California Wonder the specificleaf weight (dry weight per unit laminar area) at leaf unfoldingis three times higher in the eighth leaf than in the first leafproduced. Intermediate leaves exhibit a trend between the twoThe change in specific leaf weight during laminar expansionis greatest in leaf 1 and least (sometimes zero) in leaf 8.Large changes in specific leaf weight during laminar expansionare associated with a large degree of palisade cell expansion,while leaves showing smaller rates of change have less palisadecell expansion but cell division is more evident. At leaf unfoldingthe fraction I protein content per unit laminar area is higherin upper than in lower leaves. Ribulose diphosphate carboxylaseactivity per unit laminar area and ¹⁴CO₂ fixation per unit laminararea have a similar pattern of development in all leaves andshow no correlation with the changes in specific leaf weight.The peak of activity in all leaves occurs when the laminar areais 10 cm². These results are compared with previous data onlaminar expansion and are seen as in accord with current ideason leaf growth.     

The Growth and Development of Simulated Swards of Perennial Ryegrass: I. Leaf Growth and Dry Weight Change as Related to the Ceiling Yield of a Seedling Sward

The leaf growth, tiller production, light interception, anddry weight increase of a simulated sward of S24 perennial ryegrass(Lolium perenne) were followed during the development of thesward from a collection of two-leaved seedlings to a closedcanopy with an LAI of 23, of which 15 consisted of green leaflaminae. The dry weight of live shoots increased exponentiallyat first, but then entered a long linear phase of increase.This was equivalent to a crop growth rate of 200 Kg ha^–1day^–1 and a conversion efficiency of radiant energy (400–700nm) of 7.2 per cent. Towards the end of the growth period therate of increase of live shoots declined rapidly to zero anda ceiling yield was reached equivalent to 10 metric tons ha^–1.Leaf growth continued at a high rate, but was equalled by therate of leaf death, so that the weight of live leaf tissue remainedconstant. By this time the swards had achieved a stable tillerpopulation (about 1 cm^–1), each tiller bore a constantnumber of live leaves (about three), and the length of eachnewly expanded leaf equalled the length of the old leaf it replaced(about 70 cm). The swards were grown in Perlite so that in theabsence of soil fauna dead leaves accumulated at the base ofthe sward where, after 12 weeks, they accounted for 19 per centof the total weight of dry matter produced.     

Analysis of Photosynthetic Activity at the Leaf and Canopy Levels from Reflectance Measurements: A Case Study

The photochemical reflectance index (PRI), based on reflectance signatures at 531 and 570 nm, and associated with xanthophyll pigment inter-conversion and related thylakoid energisation, was evaluated as an indicator of photosynthetic function in a Mediterranean holm oak (Quercus ilex L.) coppice. The chlorophyll fluorescence pulse-amplitude-modulation and the eddy correlation techniques were used to estimate the photosystem 2 photochemical efficiency of leaves and the CO₂ flux over the canopy, respectively. The reflectance and fluorescence techniques yielded identical estimates of the photosynthetic activity in leaves exposed to dark-light-dark cycles or to a variable irradiance in laboratory. However, there was no such correlation between photosynthetic performance and PRI when applied to a sun-exposed canopy in field conditions. Fluorescence profiles inside the canopy and especially a helpful use of multispectral reflectance imaging highlight the limitations of such method.     

Effect of Growth Regulators and Herbicides on Photosynthetic Partial Reactions in Isolated Leaf Cells

The effect of indoleacetic acid, gibberellic acid, 2,4-dichloro-phenoxyacetic acid and amitrole at various concentration levels ranging from 0.05 to 1.0 mM on the photosynthetic evolution of O₂ and ¹⁴CO₂ fixation by isolated leaf cells was studied. The plant growth regulators enhanced O₂ evolution and ¹⁴CO₂ fixation at low concentrations and were inhibitory beyond a critical level. The amitrole had an inhibitory effect at all the concentration levels used. All the substances exhibited similar patterns of effect on the ferricyanide reduction by isolated chloroplasts and on the electron transport rates of sub-chloro-plast particles containing PS-I and PS-II independently, under non-phosphorylating conditions. As was seen from the response in all the three electron transport systems of the chloroplast studied, the electron transport chain connecting PS-II and PS-I could be considered as a possible site of action at least for the growth regulating substances as it is the only part that is common to all the three reactions. The phosphorylation associated with this part of the electron transport was “inhibited” by the substances even at the lowest concentration used. The stimulation of non-phosphorylating electron flow, with a simultaneous reduction in the rate of ATP synthesis, at low concentration levels indicated that these substances played a possible uncoupling role. The amitrole on the other hand appeared to have a generalized non-specific inhibitory action on all the partial reactions of photosynthesis.     

土壤干旱对水稻叶片光合速率和碳酸酐酶活性的影响

以适应性广的水稻品种“汕优 6 3”为材料 ,具有较高的光合速率但适应性较差的品系“NAU30 3”为对照 ,比较了不同阶段的叶片光合机构对于干旱处理的适应性。结果表明“汕优 6 3”具有较广泛的适应性 ,在逆境条件下仍能维持较高的光合速率 ,这可能和叶片中碳酸酐酶活性对逆境的响应程度高有关。这种对干旱逆境的适应性反应只在叶片光合功能的可逆衰退阶段发生     

Leaf Photosynthetic Activity in Six Temperate Grass Varieties Grown in Contrasting Light and Temperature Environments

Three populations of each of Lolium perenne and Lolium multiflorumwere grown at four temperatures at each of three light intensities.Concurrent studies were made on the response of leaf photosyntheticactivity and leaf structure of newly-expanded leaves of 7-weekold seedlings of each of the populations to the contrastinggrowth environments. Photochemical efficiencies, leaf conductances, photorespirationconstants and apparent activation energies for photosynthesiswere calculated for each population in each of the twelve growthenvironments. Photosynthetic rates at light saturation were expressed on thebasis of leaf area, of leaf volume and of leaf mesophyll tissuevolume. Photosynthetic rates were also measured under differentassay conditions. By expressing photosynthetic rates on a leaf volume basis, variationbetween populations and growth environments resulting from leafstructural changes were partially removed.     

GRO家族:与细胞生长相关的趋化因子

ＲＯ(ｇｒｏｗｔｈ ｒｅｌａｔｅｄｏｎｃｏｇｅｎｅ)家族是一类属于ＣＸＣ族的趋化因子 ,包括ＧＲＯα、ＧＲＯβ、ＧＲＯγ ,系统命名为ＣＸＣＬ1、ＣＸＣＬ2、ＣＸＣＬ3。1 987年分离并测序了ＧＲＯｃＤＮＡ ,并推测其表达与细胞生长相关 ,类似于ｃ ｆｏｓ原癌基因 ,因此而得名为ＧＲＯ。因ＧＲＯ可如丝裂原样刺激黑色素瘤细胞生长 ,曾被称为ＭＧＳＡ(ｍｅｌａｎｏｍａｇｒｏｗｔｈｓｔｉｍｕｌａｔｏｒｙａｃｔｉｖｉｔｙ)。小鼠的相对应基因为ＫＣ ,发现于ＣＯＳ细胞 ,是ＰＤＧＦ(ｐｌａｔｅｌｅｔ ｄｅｒｉｖｅｄｇｒｏｗｔｈｆａｃｔ…     

Leaf Development in Lolium temulentum: Photosynthesis and Photosynthetic Proteins in Leaves Senescing under Different Irradiances

Changes in carbon fixation rate and the levels of photosyntheticproteins were measured in fourth leaves of Lolium temulentumgrown until full expansion at 360 µmol quanta m^–2s^–1 and subsequently at the same irradiance or shadedto 90 µmol m^–2 s^–1. Ribulose-1,5-bisphosphatecarboxylase/oxygenase (Rubisco), light-harvesting chlorophylla/b protein of photosystem II (LHCII), 65 kDa protein of photosystemI (PSI), cytochrome f (Cytf) and coupling factor 1 (CF₁) declinedsteadily in amount throughout senescence in unshaded leaves.In shaded leaves, however, the decrease in LHCII and the 65kDa protein was delayed until later in senescence whereas theamount of Cyt f protein decreased rapidly following transferto shade and was lower than that of unshaded leaves at the earlyand middle stages of senescence. Decreases in the Rubisco andCF₁ of shaded leaves occurred at slightly reduced rates comparedwith unshaded leaves. These results indicate that chloroplastproteins in fully-expanded leaves are controlled individually,in a direction appropriate to acclimate photosynthesis to agiven irradiance during senescence. (Received August 20, 1992; Accepted January 5, 1993)     

柳树叶浸提液对四尾栅藻生长特性及光合效率的影响

以四尾栅藻（Scenedesmusquadncauda）为研究对象,应用柳树（sn如babylonica）叶浸提液研究了其对四尾栅藻密度、细胞形态、叶绿素含量及光合效率的影响。结果表明：各浓度柳树叶浸提液处理组四尾栅藻密度均低于对照组,且较高浓度浸提液处理组藻密度更低。浓度为10g／L、20g／L和30g／L的柳树叶浸提液对四尾栅藻的最大抑制率分别为47．0％、54．6％和62．3％。根据浓度一效应关系方程,计算出对应的柳叶浸提液96h对四尾栅藻的半效应浓度（EC,。值）为23．32g/L.加入柳树叶浸提液后,四尾栅藻细胞边缘变得不规则,细胞体变透明,部分细胞溶解。在柳树叶浸提液作用下四尾栅藻叶绿素a含量始终保持在很低的水平。lO∥L、20∥L和30∥L处理组叶绿素含量最低分别为173．12t,g／L、124．18斗∥L、37．62斗g／L。实验开始第ld后各浓度柳树叶浸提液处理组Fv／Fm显著下降（P〈0．01）,第24d柳树浸提液浓度效应较为明显,大致是浸提液浓度越高,四尾栅藻PSⅡ最大光合效率越低。     

不同培养基对发菜细胞生长和光合活性的影响

研究测定了发菜(NostocflagelliformeBorn.etFlah.)细胞在不同培养基中的生长速率、光合作用和叶绿素荧光活性。结果显示培养11d后:Detmer培养基中叶绿素a的含量为1.08mg/L,Kratz-Myers培养基中叶绿素a的含量为1.87mg/L,水生104号培养基中叶绿素a的含量为1.21mg/L,BG11培养基中叶绿素a的含量为2.18mg/L,表明在BG11培养基中培养的细胞具有最高生长速率;与另外4种不同浓度的BG11培养基相比,上述BG11培养基培养的发菜具有最大的光合速率Pm(218.1μmolO2.mg-1chla.h-1)和最高的PSII光化学效率(Fv/Fm=0.349)。实验结果表明,BG11是适合发菜生长的培养基,对其光合作用和叶绿素荧光活性具有显著促进作用。     

Acyclic Nucleotides Related to Clitocine: Synthesis and Anti-HIV Activity

Abstract

The syntheses and antiviral activity of analogues of the anti-HIV agents PMEA, PMEDAP, (R)-PMPA, (R)-PMPDAP are described. In these analogues the adenine moiety is replaced by 4,6-diamino-5-nitro-pyrimidine (the aglycon of clitocine) or 2,4,6-triamino-5-nitro-pyrimidine. The synthesis of similar acyclic phosphonates related to PMEG and (R)-2′-methyl-PMEG is also reported. Some compounds proved to be active as anti-HIV agents.