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1.
Fagerberg WR 《Protoplasma》2007,230(1-2):51-59
Summary. Electromagnetic radiation (EMR) in the 400–700 nm bandwidth of photosynthetically active radiation (PAR) has been established
as an important source of energy for photosynthesis and environmental signals regulating many aspects of green-plant life.
Above-ambient levels of UV-B radiation (290–320 nm) under high-PAR conditions have been shown to elicit responses in chloroplasts
of Brassica napus similar to those of chloroplasts at low-PAR exposure (W. Fagerberg and J. Bornman, Physiol. Plant. 101: 833–844, 1997). The
question arises as to whether UV at normal levels can also evoke similar responses. Here we provide evidence that even below-ambient
levels of UV-B (1/28 ambient; Durham, N.H., U.S.A., 1200 hours, March) were capable of inducing an increase in thylakoid surface
area relative to the chloroplast volume typical of a low-PAR response (shade response) in sunflowers. This response occurred
even though leaves were concurrently exposed to PAR levels that normally induce a “sun” or high-PAR response in the absence
of UV-B. Subambient levels of UV-B were also associated with a decrease in chloroplast and starch volume. Exposure to levels
of UV-A 1/10 of ambient appeared to enhance the high-PAR response of the chloroplast, characterized by an increase in the
amounts of stored starch, an increase in chloroplast volume density ratio values, and a decrease in thylakoid surface area
density ratios relative to the high-light controls. These effects were opposite to those seen in UV-B-exposed tissue. In a
general sense, subambient levels of UV-B evoked a response similar to that elicited by low-PAR irradiance, while subambient
UV-A elicited responses similar to those typical of high-PAR irradiance. The fact that below-ambient levels of UV altered
a normal chloroplast structural response to PAR provides evidence that UV may be an important environmental signal for plants.
Correspondence and reprints: Department of Plant Biology, University of New Hampshire, Durham, NH 03824, U.S.A.
This is Scientific Contribution number 2292 from the New Hampshire Agricultural Experiment Station. 相似文献
2.
Summary. In leaf mesophyll cells of transgenic Arabidopsis thaliana plants expressing GFP in the chloroplast, stromules (stroma-filled tubules) with a length of up to 20 μm and a diameter of
about 400–600 nm are observed in cells with spaces between the chloroplasts. They appear extremely dynamic, occasionally branched
or polymorphic. In order to investigate the effect of temperature on chloroplasts, we have constructed a special temperature-controlled
chamber for usage with a light microscope (LM-TCC). This LM-TCC enables presetting of the temperature for investigation directly
at the microscope stage with an accuracy of ±0.1 °C in a temperature range of 0 °C to +60 °C. With the LM-TCC a temperature-dependent
appearance of chloroplast protrusions has been found. These structures have a considerably smaller length-to-diameter ratio
than typical stromules and reach a length of 3–5 μm. At 5–15 °C (low temperatures), almost no chloroplast protrusions are
observed, but they appear with increasing temperatures. At 35–45 °C (high temperatures), numerous chloroplast protrusions
with a beaklike appearance extend from a single chloroplast. Interaction of stromules with other organelles has also been
investigated by transmission electron microscopy. At 20 °C, transverse sections of stromules are frequently observed with
a diameter of about 450 nm. A close membrane-to-membrane contact of stromules with the nucleus and mitochondria has been visualised.
Golgi stacks and microbodies are found in the spatial vicinity of stromules. At 5 °C, virtually no chloroplast protrusions
or stromules are observed. At 35 °C, chloroplast protrusions are present as broader thylakoid-free stroma-filled areas, resulting
in an irregular chloroplast appearance.
Correspondence and reprints: Department of Physiology and Cell Physiology of Alpine Plants, Institute of Botany, University
of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria. 相似文献
3.
This article examines the geological evidence for the rise of atmospheric oxygen and the origin of oxygenic photosynthesis.
The evidence for the rise of atmospheric oxygen places a minimum time constraint before which oxygenic photosynthesis must
have developed, and was subsequently established as the primary control on the atmospheric oxygen level. The geological evidence
places the global rise of atmospheric oxygen, termed the Great Oxidation Event (GOE), between ~2.45 and ~2.32 Ga, and it is
captured within the Duitschland Formation, which shows a transition from mass-independent to mass-dependent sulfur isotope
fractionation. The rise of atmospheric oxygen during this interval is closely associated with a number of environmental changes,
such as glaciations and intense continental weathering, and led to dramatic changes in the oxidation state of the ocean and
the seawater inventory of transition elements. There are other features of the geologic record predating the GOE by as much
as 200–300 million years, perhaps extending as far back as the Mesoarchean–Neoarchean boundary at 2.8 Ga, that suggest the
presence of low level, transient or local, oxygenation. If verified, these features would not only imply an earlier origin
for oxygenic photosynthesis, but also require a mechanism to decouple oxygen production from oxidation of Earth’s surface
environments. Most hypotheses for the GOE suggest that oxygen production by oxygenic photosynthesis is a precondition for
the rise of oxygen, but that a synchronous change in atmospheric oxygen level is not required by the onset of this oxygen
source. The potential lag-time in the response of Earth surface environments is related to the way that oxygen sinks, such
as reduced Fe and sulfur compounds, respond to oxygen production. Changes in oxygen level imply an imbalance in the sources
and sinks for oxygen. Changes in the cycling of oxygen have occurred at various times before and after the GOE, and do not
appear to require corresponding changes in the intensity of oxygenic photosynthesis. The available geological constraints
for these changes do not, however, disallow a direct role for this metabolism. The geological evidence for early oxygen and
hypotheses for the controls on oxygen level are the basis for the interpretation of photosynthetic oxygen production as examined
in this review. 相似文献
4.
Hao H Ling C Xiaoqing L Chao L Weiqian C Yun L Fashui H 《Biological trace element research》2008,122(2):157-167
Chloroplasts were isolated from spinach cultured in calcium-deficient, cerium-chloride-administered calcium-present Hoagland’s
media or that of calcium-deficient Hoagland’s media and demonstrated the effects of cerium on distribution of light energy
between photosystems II and I and photochemical activities of spinach chloroplast grown in calcium-deficient media. It was
observed that calcium deprivation significantly inhibited light absorption, energy transfer from LHCII to photosystemII, excitation
energy distribution from PSI to PSII, and transformation from light energy to electron energy and oxygen evolution of chloroplasts.
However, cerium treatment to calcium-deficient chloroplasts could obviously improve light absorption and excitation energy
distribution from photosystem I to photosystem II and increase activity of whole chain electron transport, photosystems II
and I DCPIP photoreduction, and oxygen evolution of chloroplasts. The results suggested that cerium under calcium deficiency
condition could substitute for calcium in chloroplasts, maintain the stability of chloroplast membrane, and improve photosynthesis
of spinach chloroplast, but the mechanisms still need further study. 相似文献
5.
The review focuses on the energetic and regulatory role of proton potential in the activity of chloroplasts, the light energy-converting organelles of plant cells. Mechanisms of generation of the transmembrane difference of electrochemical potentials of hydrogen ions in the chloroplast thylakoid membranes are considered. Methods for measuring the intrathylakoid pH in chloroplasts are described. It is shown that under conditions of phosphorylation in chloroplasts, the pH of the intrathylakoid space decreases moderately (pHin ⩾ 6.0–6.2, at the stroma pHout ∼ 7.8–8.0), with a corresponding concentration component of equal to ΔpH ⩽ 1.6–2.0. On analyzing the energy and structural features of ATP synthase of chloroplasts, we conclude that the energy stored as the concentration component of the proton potential ΔpH is sufficient to sustain ATP synthesis. The mechanisms of pH-dependent regulation of electron transport in chloroplasts (photosynthetic control of electron transport, enhancement of non-photochemical quenching of chlorophyll excitation in the light-harvesting antenna, light-induced activation of the Calvin-Benson cycle reactions, activation of ATP synthase) are considered briefly. 相似文献
6.
Chloroplast DNA in Expanding Spinach Leaves 总被引:2,自引:0,他引:2
The proportion of chloroplast DNA in total DNA from spinachleaves has been measured using the second order reassociationkinetics of a 3H-labelled chloroplast DNA probe in total DNAextracts. There was no significant difference between the proportionof chloroplast DNA in the basal and distal halves of 2 cm leavesand in the distal halves of 5, 8, and 10 cm leaves. The meanof all the observations was 21.1 ± 0.7%. There was littlechange in the average total DNA content of cells from any ofthe leaves but cells from larger leaves contained 130170chloroplasts while cells from the basal half of 2 cm leavescontained about 20 chloroplasts which were smaller than thosefrom the larger leaves. Consequently the average number of copiesof the plastome per chloroplast in large leaves was about 30(5 x 1015 g DNA) and in the smaller chloroplasts in thebase of 2 cm leaves was 200 (32 x 1015 g DNA). Stainingwith the DNA fluorochrome 4, 6-diamidino-2 phenyl indole (DAPI)showed 1015 plastid nucleoid areas in chloroplasts oflarger leaves, suggesting there are 23 copies of theplastome per plastid nucleoid. 相似文献
7.
N. V. Astakhova I. N. Demin N. V. Naraikina T. I. Trunova 《Russian Journal of Plant Physiology》2011,58(1):18-23
Effects of the desA gene from the cyanobacterium Synechocystis sp. encoding Δ12 acyl-lipid desaturase and increasing the level of unsaturated fatty acids (linoleic acid (18:2) primarily)
in membrane lipids, which was inserted into potato (Solanum tuberosum L., cv. Desnitsa) plants, on chloroplast ultrastructure and plant tolerance to low temperatures were studied. The main attention
was focused on modifications in the chloroplast structure and their possible relation to potato plant tolerance to oxidative
and low-temperature stresses under the influence to their transformation with the Δ12 acyl-lipid desaturase gene from cyanobacterium
(desA-licBM3-plants). Morphometric analysis showed that, in comparison with wild-type (WT) plants, in desA-licBM3-plants the number of grana in chloroplasts increased substantially. The total number of thylakoids in transformant chloroplasts
was almost twice higher than in WT plants. The number of plastoglobules per chloroplast of transformed plants increased by
25%. A marked increase in the number of grana, total number of thylakoids, and the number of plastoglobules in chloroplasts
of desA-licBM3-plants indicates their more intense lipid metabolism, as compared with WT plants, and this resulted in the conservation of
some part of lipids in plastoglobules. In addition, the expression of heterological desA gene encoding Δ12 acyl-lipid desaturase positively influenced stabilization of not only structure but also functioning of
chloroplast membranes, thus preventing a transfer of electrons from the ETR to oxygen and subsequent ROS generation at hypothermia.
This was confirmed by the analysis of the rate of superoxide anion generation in tested genotypes. 相似文献
8.
Intracellular chloroplast photorelocation in the moss Physcomitrella patens is mediated by phytochrome as well as by a blue-light receptor 总被引:3,自引:0,他引:3
The light-induced intracellular relocation of chloroplasts was examined in red-light-grown protonemal cells of the moss Physcomitrella patens. When irradiated with polarized red or blue light, chloroplast distribution in the cell depended upon the direction of the
electrical vector (E-vector) in both light qualities. When the E-vector was parallel to the cross-wall (i.e. perpendicular
to the protonemal axis), chloroplasts accumulated along the cross-wall; however, no accumulation along the cross-wall was
observed when the E-vector was perpendicular to it (i.e. parallel to the protonemal axis). When a part of the cell was irradiated
with a microbeam of red or blue light, chloroplasts accumulated at or avoided the illumination point depending on the fluence
rate used. Red light of 0.1–18 W m−2 and blue light of 0.01–85.5 W m−2 induced an accumulation response (low-fluence-rate response; LFR), while an avoidance response (high-fluence-rate response;
HFR) was induced by red light of 60 W m−2 or higher and by blue light of 285 W m−2. The red-light-induced LFR and HFR were nullified by a simultaneous background irradiation of far-red light, whereas the
blue-light-induced LFR and HFR were not affected at all by this treatment. These results show, for the first time, that dichroic
phytochrome, as well as the dichroic blue-light receptor, is involved in the chloroplast relocation movement in these bryophyte
cells. Further, the phytochrome-mediated responses but not the blue-light responses were revealed to be lost when red-light-grown
cells were cultured under white light for 2 d.
Received: 7 September 1999 / Accepted: 15 October 1999 相似文献
9.
Tomoya Fujita James C. Ogbonna Hideo Tanaka Hideki Aoyagi 《Journal of applied phycology》2009,21(2):185-191
The effects of reactive oxygen species (ROS) on α-tocopherol production in mitochondria and chloroplasts of Euglena gracilis were investigated. Addition of an organic carbon source to the medium resulted in increased mitochondrial activity, intracellular
O2
- concentration and α-tocopherol productivity in E. gracilis W14ZUL (a chloroplast deficient mutant). α-Tocopherol productivity of the wild-type strain (with both mitochondria and chloroplast)
was higher than that of the W14ZUL strain. In the case of the wild strain, the O2
− generated in chloroplasts was efficiently scavenged by the α-tocopherol synthesized inside the chloroplast. In photoheterotrophic
culture (with an organic carbon source), there was a positive correlation between α-tocopherol production and O2
− generation. Addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (an inhibitor of photosynthesis) resulted in increased O2
− generation and α-tocopherol productivity. These results indicate that the ROS generated in mitochondria and chloroplasts
play important roles in α-tocopherol production by E. gracilis. The presence of chloroplasts and generation of intracellular ROS are important for efficient production of α-tocopherol. 相似文献
10.
Irrungen,Wirrungen? The Mehler reaction in relation to cyclic electron transport in C3 plants 总被引:5,自引:0,他引:5
Heber U 《Photosynthesis research》2002,73(1-3):223-231
Plants not only evolve but also reduce oxygen in photosynthesis. Considerable oxygen uptake occurs during photorespiration
of C3 plants. Controversies exist on whether direct oxygen reduction in the Mehler reaction together with associated electron
transport is also a major sink of electrons when leaves are exposed to sunlight. Here, preference is given to the view that
it is not. Whereas photorespiration consumes ATP, the Mehler reaction does not. In isolated chloroplasts photosynthesizing
in the presence of saturating bicarbonate, the Mehler reaction is suppressed. In the water – water cycle of leaves, which
includes the Mehler reaction, water is oxidized and electrons flow through Photosystems II and I to oxygen producing water.
The known properties of coupled electron transport suggest that the water – water cycle cannot act as an efficient electron
sink. Rather, by contributing to thylakoid acidification it plays a role in the control of Photosystem II activity. Cyclic
electron transport competes with the Mehler reaction for electrons. Both pathways can help to defray possible ATP deficiencies
in the chloroplast stroma, but play a more important role by making intrathylakoid protein protonation possible. This is a
necessary step for the dissipation of excess excitation energy as heat. Linear electron flow to oxygen relieves the inhibition
of cyclic electron transport, which is observed under excessive reduction of intersystem electron carriers. In turn, cyclic
electron transport replaces functions of the linear pathway in the control of Photosystem II when oxygen reduction is decreased
at low temperatures or, experimentally, when the oxygen concentration of the gas phase is low. Thus, cyclic electron flow
acts in flexible relationship with the water–water cycle to control Photosystem II activity.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
We examined morphological and ultrastructural differences in chloroplasts of cotton leaves and the fruiting organs, bract,
and capsule wall to advance our understanding of their commonly observed differences in photosynthetic efficiency. Chloroplasts
from leaves were large (7.1 μm long in cross section), lens shaped with a well developed membrane system differentiated into
grana and stroma lamellae that occupied the large cross-sectional area (12.3 μm2) of the organelle. A few small plastoglobuli and starch grains were scattered in the stroma region. The bract chloroplasts
were correlative of leaf chloroplasts in size (6.8 μm in length) and shape with the exception that the bract chloroplasts
exhibited greater thylakoid number per granum (15.8) than the leaf chloroplasts (10.5). In contrast to leaf and bract, the
capsule wall chloroplasts were smaller in size (4.3 μm) and cross sectional area (6.8 μm2) than either the leaf or bract. The most intriguing feature of the capsule wall chloroplasts was its domination by large
starch granules (5.3 μm2) in the stroma which filled the whole chloroplast coercing the membrane system to move towards the periphery of the organelle.
Grana number and thylakoids per granum were lowest in the capsule wall chloroplasts.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
Xiaolan Gong Ying Wang Chao Liu Sisi Wang Xiaoyang Zhao Min Zhou Na Li Yun Lu Fashui Hong 《Biological trace element research》2010,136(3):372-382
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. 相似文献
13.
Berg R Königer M Schjeide BM Dikmak G Kohler S Harris GC 《Photosynthesis research》2006,87(3):303-311
A new microcontroller-based photometric instrument for monitoring blue light dependent changes in leaf transmission (chloroplast movement) was developed based on a modification of the double-beam technique developed by Walzcak and Gabrys [(1980) Photosynthetica 14: 65–72]. A blue and red bicolor light emitting diode (LED) provided both a variable intensity blue actinic light and a low intensity red measuring beam. A phototransistor detected the intensity of the transmitted measuring light. An inexpensive microcontroller independently and precisely controlled the light emission of the bicolor LED. A typical measurement event involved turning off the blue actinic light for 100 μs to create a narrow temporal window for turning on and measuring the transmittance of the red light. The microcontroller was programmed using LogoChip Logo (http://www.wellesley.edu/Physics/Rberg/logochip/) to record fluence rate response curves. Laser scanning confocal microscopy was utilized to correlate the changes in leaf transmission with intercellular chloroplast position. In the dark, the chloroplasts in the spongy mesophyll exhibited no evident asymmetries in their distribution, however, in the palisade layer the cell surface in contact with the overlying epidermis was devoid of chloroplasts. The low light dependent decrease in leaf transmittance in dark acclimated leaves was correlated with the movement of chloroplasts within the palisade layer into the regions previously devoid of chloroplasts. Changes in leaf transmittance were evident within one minute following the onset of illumination. Minimal leaf transmittance was correlated with chloroplasts having retreated from cell surfaces perpendicular to the incident light (avoidance reaction) in both spongy and palisade layers.Electronic Supplementary Material Supplementary material is available for this article at 相似文献
14.
Chloroplasts change their intracellular positions in response to their light environment. Under darkness, chloroplasts assume
special positions that are different from those under light conditions. Here, we analyzed chloroplast dark positioning using
Adiantum capillus-veneris gametophyte cells. When chloroplasts were transferred into darkness, during the first 1–5 h, they moved towards the anticlinal
cell walls bordering the adjacent cells rather rapidly. Then, they slowed down and accumulated at the anticlinal walls gradually
over the following 24–36 h. The chloroplast movements could be roughly classified into two different categories: initial rapid
straight movement and later, slow staggering movement. When the chloroplast accumulation response was induced in dark-adapted
cells by partial cell irradiation with a microbeam targeted to the center of the cells, chloroplasts moved towards the beam
spot from the anticlinal walls. However, when the microbeam was switched off, they moved to the nearest anticlinal walls and
not to their original positions if they were not the closest, indicating that they know the direction of the nearest anticlinal
wall and do not have particular areas that they migrate to during dark positioning. 相似文献
15.
High expression of foot-and-mouth disease virus structural protein VP1 in tobacco chloroplasts 总被引:5,自引:0,他引:5
A tobacco chloroplast expression vector, pTRVP1, containing the foot-and-mouth disease virus (FMDV) VP1 gene and the selective
marker aadA gene, was constructed and transferred to tobacco by biolistic method. Three resistant lines were obtained through spectinomycin
selection, and each transgenic line was subjected to a second round of spectinomycin selection. PCR and PCR southern blot
analysis revealed that the VP1 gene had integrated into the chloroplast genome. Western blot and quantification ELISA assays
indicated that the VP1 gene was expressed in tobacco chloroplasts and accounted for 2–3% of total soluble protein. This suggested
that plant chloroplasts were an efficient expression system for the potential production of recombinant antigens in plants. 相似文献
16.
Maize (Zea mays L.) seedlings of two cultivars (cv. Bastion adapted to W. Europe, and cv. Batan 8686 adapted to the highlands of Mexico),
raised in a glasshouse (19–25 °C), were transferred to 4.5 or 9 °C at photon flux density (PPFD) of 950 μmol m−2 s−1 with 10-h photoperiod for 58 h and then allowed to recover at 22 °C for 16 h (14 h dark and 2 h at PPFD of 180 μmol m−2 s−1). The ultrastructural responses after 4 h or 26 h at 4.5 °C were the disappearance of starch grains in the bundle sheath
chloroplasts and the contraction of intrathylakoid spaces in stromal thylakoids of the mesophyll chloroplasts. At this time,
bundle sheath chloroplasts of cv. Batan 8686 formed peripheral reticulum. Prolonged stress at 4.5 °C (50 h) caused plastid
swelling and the dilation of intrathylakoid spaces, mainly in mesophyll chloroplasts. Bundle sheath chloroplasts of cv. Batan
8686 seedlings appeared well preserved in shape and structure. Batan 8686 had also higher net photosynthetic rates during
chilling and recovery than Bastion. Extended leaf photobleaching developed during the recovery period after chilling at 4.5
°C. This was associated with collapsed chloroplast envelopes, disintegrated chloroplasts and very poor staining. 相似文献
17.
O. V. Avercheva E. M. Bassarskaya T. V. Zhigalova Yu. A. Berkovich S. O. Smolyanina M. R. Leont’eva A. N. Erokhin 《Russian Journal of Plant Physiology》2010,57(3):382-391
Leaf mesostructure, photochemical activity, and chloroplast photophosphorylation (PP) in the fourth true leaf of 28-day-old
Chinese cabbage (Brassica chinensis L.) plants were investigated. Plants were grown under a light source based on red (650 nm) and blue (470 nm) light-emitting
diodes (LED) with red/blue photon flux ratio of 7: 1 and under illumination with high-pressure sodium lamp (HPSL) at photon
flux densities of 391 ± 24 μmol/(m2 s) (“normal irradiance”) and 107 ± 9 μmol/(m2 s) (“low irradiance”) in photosynthetically active range. At normal irradiance, the leaf area in plants grown under HPSL
was twofold higher than in LED-illuminated plants; other parameters of leaf mesostructure were little affected by spectral
quality of incident light. The lowering of growth irradiance reduced the majority of leaf mesostructure parameters in plants
grown under illumination with HPSL, whereas in LED-illuminated plants the lowered irradiance reduced only specific leaf weight
but increased the leaf thickness and dimensions of mesophyll cells and chloroplasts. The photochemical activity of isolated
chloroplasts was almost independent of growth irradiance and light spectral quality. Light quality and intensity used for
plant growing had a considerable impact on PP in chloroplasts. At normal light intensity, the highest activity of noncyclic
PP in chloroplasts was observed for plants grown under HPSL; at low light intensity the highest rates of PP were noted for
plants grown under LED. The P/2e− ratio, which characterizes the degree of PP coupling to electron transport in the chloroplast electron transport chain, showed
a similar pattern. Thus, the narrow-band spectrum of the light source had little influence on leaf mesostructure and electron
transport rates. However, this spectrum significantly affected the chloroplast PP activity. The PP patterns at low and normal
light intensities were opposite for plants grown under LED and HPSL light sources. We suppose that growing plants under LED
array at normal light intensity disturbed the chloroplast coupling system, thus preventing the effective use of light energy
for ATP synthesis. At low light intensity, chloroplast PP activity was significantly higher under LED illumination, but plant
growth was suppressed because of impaired adaptation to low light intensity. 相似文献
18.
Mitochondrial contribution to photosynthetic metabolism during the transition from low light (25–100 μmol quanta m−2 s−1, limiting photosynthesis) to high light (500 μmol quanta m−2 s−1, saturating photosynthesis) was investigated in protoplasts from barley (Hordeum vulgare) leaves. After the light shift, photosynthetic oxygen evolution rate increased rapidly during the first 30–40 s and then declined up to 60–70 s after which the rate increased to a new steady-state after 80–110 s. Rapid fractionation of protoplasts was used to follow changes in sub-cellular distribution of key metabolites during the light shift and the activation state of chloroplastic NADP-dependent malate dehydrogenase (EC 1.1.1.82) was measured. Although oligomycin (an inhibitor of the mitochondrial ATP synthase) affected the metabolite content of protoplasts following the light shift, the first oxygen burst was not affected. However, the transition to the new steady-state was delayed. Rotenone (an inhibitor of mitochondrial complex I) had similar, but less pronounced effect as oligomycin. From the analysis of metabolite content and sub-cellular distribution we suggest that the decrease in oxygen evolution following the first oxygen burst is due to phosphate limitation in the chloroplast stroma. For the recovery the control protoplasts can utilize ATP supplied by mitochondrial oxidative phosphorylation to quickly overcome the limitation in stromal phosphate and to increase the content of Calvin cycle metabolites. The oligomycin-treated protoplasts were deficient in cytosolic ATP and thereby unable to support Calvin cycle operation. This resulted in a delayed capacity to adjust to a sudden increase in light intensity. 相似文献
19.
The ultrastructure and dimensions of chloroplasts in leaf mesophyll cells were quantitatively examined in three parental inbred
lines of maize (Zea mays L.) and their four hybrids subjected to two types of four-week low-temperature (LT) treatment: the abrupt onset of chilling
temperatures (“severe chilling”, SC) and the gradual, more moderate one (“moderate chilling”, MC). The relationship between
the response of individual genotypes to one or the other type of chilling was analyzed as well as the possibility to predict
the behaviour of chloroplasts in hybrids from that of their parents. Although selected parameters of chloroplast ultrastructure
(e.g. volume densities of granal and intergranal thylakoids, plastoglobuli, and peripheral reticulum) and dimensions changed due
to the exposure of maize plants to LT, no general pattern of such changes was found for this species due to the observed intraspecific
variability. The response of some genotype to SC could not be predicted from its behaviour under MC (and vice versa) and no clear rules could be applied for the inheritance of chloroplast response to chilling in the general sense. Thus,
great caution should be always taken when interpreting the results of studies aimed at the dissection of chloroplast ultrastructure
as affected by LT, particularly in case such studies are made with one genotype or under one type of chilling only. 相似文献
20.
Ioannis E. Papadakis Artemios M. Bosabalidis Thomas E. Sotiropoulos Ioannis N. Therios 《Acta Physiologiae Plantarum》2007,29(4):297-301
Leaf samples of Mn-deficient and Mn-sufficient (control) ‘Navelate’ orange plants grown in a greenhouse were taken to investigate
the effects of Mn deficiency in leaf structure and chloroplast ultrastructure. Total leaf chlorophyll concentration was significantly
lower in Mn-deficient plants than in control ones. Entire lamina thickness was not altered due to Mn deficiency. However,
Mn deficiency resulted in disorganization of mesophyll cells, mainly of palisade parenchyma cells. The number of mesophyll
chloroplasts per cellular area and their length were both affected negatively. The membranous system of chloroplasts was also
disorganized. The percentages of starch grains and plastoglobuli per chloroplast of Mn-deficient leaves were significantly
greater than those of control leaves. 相似文献