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1.
Responses of the resurrection plant <Emphasis Type="Italic">Haberlea rhodopensis</Emphasis> to high irradiance 总被引:1,自引:0,他引:1
The effect of high irradiance (HI) during desiccation and subsequent rehydration of the homoiochlorophyllous desiccation-tolerant
shade plant Haberlea rhodopensis was investigated. Plants were irradiated with a high quantum fluence rate (HI; 350 μmol m−2 s−1 compared to ca. 30 μmol m−2 s−1 at the natural rock habitat below trees) and subjected either to fast desiccation (tufts dehydrated with naturally occurring
thin soil layers) or slow desiccation (tufts planted in pots in peat-soil dehydrated by withholding irrigation). Leaf water
content was 5 % of the control after 4 d of fast and 19 d of slow desiccation. Haberlea was very sensitive to HI under all conditions. After 19 d at HI, even in well-watered plants there was a strong reduction
of rates of net photosynthesis and transpiration, contents of chlorophyll (Chl) and carotenoids, as well as photosystem 2
activity (detected by the Chl fluorescence ratio RFd). Simultaneously, the blue/red and green/red fluorescence ratios increased considerably suggesting increased synthesis of
polyphenolic compounds. Desiccation of plants in HI induced irreversible changes in the photosynthetic apparatus and leaves
did not recover after rehydration regardless of fast or slow desiccation. Only young leaves survived desiccation. 相似文献
2.
Growth Promotion of Vegetative Gametophytes of <Emphasis Type="Italic">Undaria pinnatifida</Emphasis> by Blue Light 总被引:1,自引:0,他引:1
Through an acclimation period of 10 days, compared to white light, the maximal net photosynthetic rates were significantly
higher for gametophytes of Undaria pinnatifida cultivated under blue light (400–500 nm), and were lower under red light (600–700 nm). Chlorophyll c and the carotenoid content of gametophytes were similar under blue light and red light but were much lower under white light.
The growth rate of female gametophytes under blue light was higher than that under other lights, and the growth rate of male
gametophytes showed little variation with respect to blue and white light. Male and female gametophytes were mixed together
to form sporophytes under white, blue and red light. After approximately 5 days, 50% gametophytes became fertile under blue
and white light, but remained vegetative under red light after 10 days. 相似文献
3.
The changes in photosynthetic efficiency and photosynthetic pigments during dehydration of the resurrection plantSelaginella lepidophylla (from the Chiuhahuan desert, S.W. Texas, USA) were examined under different light conditions. Changes in the photosynthetic
efficiency were deduced from chlorophyll a fluorescence measurements (Fo, Fm, and Fv) and pigment changes were measured by HPLC analysis. A small decrease in Fv/Fm was seen in hydrated stems in high light (650 μmol photons·m−2·s−1) but not in low light (50 μmol photons·m−2·s−1). However, a pronounced decline in Fv/Fm was observed during dehydration in both light treatments, after one to two hours of dehydration. A rise in Fo was observed only after six to ten hours of dehydration. Concomitant with the decrease in photosynthetic efficiency during
dehydration a rise in the xanthophyll zeaxanthin was observed, even in low-light treatments. The increase in zeaxanthin can
be related to previously observed photoprotective non-photochemical quenching of fluorescence in dehydrating stems ofS. lepidophylla. We hypothesize that under dehydrating conditions even low light levels become excessive and zeaxanthin-related photoprotection
is engaged. We speculate that these processes, as well as stem curling and self shading (Eickmeier et al. 1992), serve to
minimize photoinhibitory damage toS. lepidophylla during the process of dehydration. 相似文献
4.
B. Fernández-Marín S. J. Arroyo Alfaro J. M. Becerril J. I. García-Plazaola 《Biologia Plantarum》2012,56(2):351-356
Ferns present two alternant generations: sporophyte and gametophyte. In the present work we address the question of whether
fern gametophytes have the potential to acclimate to different irradiances as vascular plants do. We studied the gametophytes
of three different fern species belonging to the Aspleniaceae family with different ecological requirements (Asplenium trichomanes, Asplenium scoloprendrium and Ceterach officinarum). Fern spores were germinated and the gametophytes cultivated under photon flux density (PFD) of 10, 50 or 100 μmol m−2 s−1. From the early stages of spore germination (the formation of the 5-celled germinal filament), photosynthetic apparatus acclimates
showing the typical patterns of photochemical responses to high or low PFD. In agreement with the photochemical pattern of
acclimation, higher contents of xanthophyll cycle pigments and α-tocopherol was observed in plants grown under high PFD. The
α/β-carotene ratio, used as indicator of the acclimation of the photosynthetic apparatus, also sustained the initial hypothesis
except for A. trichomanes. We conclude that fern gametophytes display a complete array of photosynthetic and photoprotective traits that allow an effective
acclimation to PFD. 相似文献
5.
Comparative effects of salt-stress and alkali-stress on the growth,photosynthesis, solute accumulation,and ion balance of barley plants 总被引:7,自引:0,他引:7
We compared the effects of salt-stresses (SS, 1: 1 molar ratio of NaCl to Na2SO4) and alkali-stresses (AS, 1: 1 molar ratio of NaHCO3 to Na2CO3) on the growth, photosynthesis, solute accumulation, and ion balance of barley seedlings, to elucidate the mechanism of AS
(high-pH) damage to plants and the physiological adaptive mechanism of plants to AS. The effects of SS on the water content,
root system activity, membrane permeability, and the content of photosynthetic pigments were much less than those of AS. However,
AS damaged root function, photosynthetic pigments, and the membrane system, led to the severe reductions in water content,
root system activity, content of photosynthetic pigments, and net photosynthetic rate, and a sharp increase in electrolyte
leakage rate. Moreover, with salinity higher than 60 mM, Na+ content increased slowly under SS and sharply under AS. This indicates that high-pH caused by AS might interfere with control
of Na+ uptake in roots and increase intracellular Na+ to a toxic level, which may be the main cause of some damage emerging under higher AS. Under SS, barley accumulated organic
acids, Cl−, SO4
2−, and NO3
− to balance the massive influx of cations, the contribution of inorganic ions to ion balance was greater than that of organic
acids. However, AS might inhibit absorptions of NO3
− and Cl−, enhance organic acid synthesis, and SO4
2− absorption to maintain intracellular ion balance and stable pH. 相似文献
6.
We report the effect of UV-B radiation (0.8 ± 0.1 mW cm−2) and UV-B radiation supplemented with low-intensity PAR (∼80 μmol photons m−2 s−1) on the photosynthesis, photosynthetic pigments, phosphoglycolipids, oxidative damage, enzymatic antioxidants, and UV-absorbing
compounds in Phormidium tenue, a marine cyanobacterium. UV-B radiation resulted in a decline in photosynthesis and photosynthetic pigments leading to lower
biomass. P. tenue synthesized UV-absorbing compounds like mycosporine-like amino acids (MAAs) and scytonemin in response to UV-B radiation.
Quantity of MAAs and scytonemin was higher when UV-B was supplemented with low-level PAR. UV-B treatment also resulted in
quantitative changes in phosphoglycolipids of the membrane. The UV-B treatment resulted in a slight increase in the level
of peroxidation of cell membrane and very little increase in the activity of superoxide dismutase (SOD). Results indicate
that UV-B affected photosynthesis and that the main protective system was the synthesis of MAAs and scytonemin-like compounds
rather than antioxidant enzymes such as SOD. 相似文献
7.
Jasmonic acid affects changes in the growth and some components content in alga Chlorella vulgaris 总被引:1,自引:0,他引:1
Romuald Czerpak Alicja Piotrowska Katarzyna Szulecka 《Acta Physiologiae Plantarum》2006,28(3):195-203
The present study was undertaken to test the influence of exogenous applied jasmonic acid upon the growth and changes in some
metabolites levels in the cells of green alga Chlorella vulgaris Beijerinck (Chlorophyceae). It was found, that JA in algal cells acted in a concentration-dependent manner. Treatment with
JA at high concentrations range of 10−5–10−4 M, resulted in the decrease in cell number and reduction of major photosynthetic pigments, monosaccharides, soluble cellular
and extracellular proteins levels as well as decrease in pH of the medium. In contrast to 10−5 and 10−4 M JA, this phytohormone applied at 10−8–10−6 M induced the increase in cell number, photosynthetic pigments and monosaccharides contents, significant accumulation and
extracellular secretion of soluble proteins over control and neutralization of the medium. Quantitative changes in polypeptide
pattern of total cellular proteins after treatment with the optimal concentration of 10−7 M JA on the 7th day of cultivation as analyzed by SDS-PAGE, was also observed. JA induced synthesis de novo of 15 specific polypeptides with molecular weight 334-16 kDa which were’t detected in the control. The data suggest that
JA plays a important role in algal growth and development. 相似文献
8.
Ranjana Singh Prabhat Kumar Srivastava Vijay Pratap Singh Gunjan Dubey Sheo Mohan Prasad 《Acta Physiologiae Plantarum》2012,34(3):1119-1131
The extent of mercury (Hg) toxicity in the heterocystous cyanobacterium Nostoc muscorum grown for 72 h in three different light intensities was tested for various physiological parameters viz. growth, pigment contents, photosynthesis, respiration, reactive oxygen species (ROS), malondialdehyde formation and antioxidants.
A general reduction in growth and pigments, whole cell O2-evolution, photosynthetic electron transport activities and 14CO2-fixation was observed in a metal concentration–dependent manner, and this effect was more pronounced in high light (130 μmol
photon m−2 s−1)–exposed cells as compared to low (10 μmol photon m−2 s−1) and normal (70 μmol photon m−2 s−1) light intensity–exposed cells; however, carotenoids and respiration showed reverse trend. Among photosynthetic electron
transport activities, whole chain activity was found to be most sensitive in comparison with photosystem II (PS II) and photosystem
I (PS I). Comparing the different photosynthetic processes, 14CO2-fixation was most affected in cyanobacterial cells when exposed to Hg and different light intensities. After application
of various exogenous electron donors, diphenyl carbazide was found to be more effective to restore PS II activity, suggesting
that site of damage lies in between oxygen evolving complex and PS II. Level of oxidative stress (superoxide radical and lipid
peroxidation) was maximum at 3.0 μM of Hg when coupled with high light intensity (except hydrogen peroxide). A dose-dependent
increase in enzymatic antioxidants such as superoxide dismutase, peroxidase and catalase as well as non-enzymatic antioxidants
such as proline, ascorbate, cysteine (except under high light intensity) and non-protein thiols [NP-SH] was observed, which
further increased with the increase in light intensity. It was noticed that Hg intoxicates N. muscorum through ROS production, which is aggravated along with the increase in light intensity. Overall results suggest that the
severity of the metal stress does increase with Hg concentrations but when coupled with light, it was the light intensity
that determines the extent of Hg toxicity. 相似文献
9.
Ozone depletion is highest during spring and summer in Antarctica, coinciding with the seasonal reproduction of most macroalgae.
Propagules are the life-stage of an alga most susceptible to environmental perturbations therefore, reproductive cells of
three intertidal macroalgal species Adenocystis utricularis (Bory) Skottsberg, Monostroma hariotii Gain, and Porphyra endiviifolium (A and E Gepp) Chamberlain were exposed to photosynthetically active radiation (PAR), PAR + UV-A and PAR + UV-A + UV-B radiation
in the laboratory. During 1, 2, 4, and 8 h of exposure and after 48 h of recovery, photosynthetic efficiency, and DNA damage
were determined. Saturation irradiance of freshly released propagules varied between 33 and 83 μmol photons m−2 s−1 with lowest values in P. endiviifolium and highest values in M. hariotii. Exposure to 22 μmol photons m−2 s−1 PAR significantly reduced photosynthetic efficiency in P. endiviifolium and M. hariotii, but not in A. utricularis. UV radiation (UVR) further decreased the photosynthetic efficiency in all species but all propagules recovered completely
after 48 h. DNA damage was minimal or not existing. Repeated exposure of A. utricularis spores to 4 h of UVR daily did not show any acclimation of photosynthesis to UVR but fully recovered after 20 h. UVR effects
on photosynthesis are shown to be species-specific. Among the tested species, A. utricularis propagules were the most light adapted. Propagules obviously possess good repair and protective mechanisms. Our study indicates
that the applied UV dose has no long-lasting negative effects on the propagules, a precondition for the ecological success
of macroalgal species in the intertidal. 相似文献
10.
To maximize and sustain the productivity ofMonascus pigments, various environmental and nutritional parameters, such as the initial moisture content, pH, inoculum size, sample
size, and nutrient supplement, that influence pigment production were evaluated in solid-state cultures as follows: initial
moisture content, 50%; pH, 6.0; inoculum size 1 x 104 spore cells (grams of dry solid substrate)−1; sample size, 300 g. All supplementary nutrients (carbon, nitrogen, and mineral sources) added has inhibitory effects on
the cell growth and red pigment production. In open tray culture the maximum biomass yield and specific productivity of red
pigments were 223 mg DCW (grams of initial dry substrate)−1 and, 47.6 OD500 (DCW grams)−1 h−1, respectively. 相似文献
11.
Xiangyuan Deng Song Qin Qun Zhang Peng Jiang Yulin Cui Xiaokun Li 《Plant Cell, Tissue and Organ Culture》2009,97(3):253-261
A human acidic fibroblast growth factor gene, hafgf, was successfully transferred into Laminaria japonica (kelp) gametophytes via microprojectile bombardment using the biolistic PDS-1000/He gene gun. Following phosphinothricin
screening, PCR detection and Southern blot analysis, transgenic L. japonica gametophytes were cultivated in an illuminated bubble-column bioreactor to optimize growth conditions. A maximal final dry
cell density of 1,695 mg l−1 was obtained in a batch culture having an initial dry cell density of 129.75 mg l−1. This was achieved using an aeration rate of 1.08 l air min−1 l−1 culture in a medium containing 1.5 mM inorganic nitrate and 0.15 mM phosphate. In addition, the relationship between different
nitrogen sources and growth of transgenic gametophytes indicated that both urea and sodium nitrate were effective nitrogen
sources for cell growth, while ammonium ions inhibited growth of these gametophytes. 相似文献
12.
Giedrė Samuolienė Ramūnas Sirtautas Aušra Brazaitytė Jurga Sakalauskaitė Sandra Sakalauskienė Pavelas Duchovskis 《Central European Journal of Biology》2011,6(5):821-828
The objective was to evaluate the effect of different combinations of red (638 nm) and blue (455 nm) light produced by solid-state
light-emitting diodes (LEDs) on physiological indices (net assimilation rate, hypocotyl-to-leaf ratio, leaf area, leaf dry
weight, hypocotyl length and diameter, plant length, developed leaves), variation of photosynthetic pigments and non-structural
carbohydrates in radish (Raphanus sativus L., var. ‘Faraon’). Lighting experiments were performed under controlled conditions (total PPFD - 200 μmol m−2 s−1; 16 h photoperiod; 14/18°C night/day temperature). The LED conditions: 638 nm; 638 + 5% 455 nm; 638 + 10% 455 nm; 638 + 10%
455 + 731 nm; 638 + 10% 455 + 731 + 669 nm. Our results showed that radishes grown under red (638 nm) alone were elongated,
and the formation of hypocotyl was weak. The net assimilation rate, hypocotyl-to-leaf ratio, and leaf dry weight also were
low due to the low accumulation of photosynthetic pigments and non-structural carbohydrates in leaves. The supplemented blue
(455 nm) light was necessary for the non-structural carbohydrates distribution between radish storage organs and leaves which
resulted in hypocotyl thickening. Red alone (638 nm) or in combination with far-red (731 nm), or red669 for radish generative
development was required. 相似文献
13.
The effects of daylength, irradiance and spore settlement density on the growth, maturation and sporophyte production of Undaria pinnatifida (Harvey) Suringar gametophytes were examined using a factorial experimental design in culture. The growth of Undaria gametophytes increased with increasing daylength (8, 12 and 16 h), but the maximum fertility occurred at a daylength of 12
h followed by 8 and 16 h. Gametophytes grew better at the 16 h daylength under the same mean daily irradiance (MDI) of 20
μmol photons m−2 s−1. However, the fertility was higher at the short daylength (8 h), indicating that the maturation of U. pinnatifida gametophytes is influenced by daylength rather than by the MDI. Vegetative growth and sporophyte production of gametophytes
were better at 60 μmol photons m−2 s−1 than at 30 μmol photons m−2 s−1 under a 8:16 h LD (Light: Dark) cycle, and their growth and maturation were density-dependant in 16 and 12 h daylength, respectively.
These results suggest that the U. pinnatifida gametophytes require a certain amount of light for the growth and reproduction, and intraspecific competition occurred under
the optimal growth and maturation conditions. However, the sporophyte recruits per unit has been enhanced with increasing
spore settlement density at 8 and 12 h daylengths indicating that high settlement density gives a benefit for maintaining
population, even though the sporophyte production of each female plant is inhibited. In conclusion, the vegetative growth,
reproduction and sporophyte production of U. pinnatifida gametophytes are retarded at a low irradiance above growth saturation and a high settlement density, and are determined by
daylength. 相似文献
14.
Karen L. Koster Ronald A. Balsamo Catherine Espinoza Melvin J. Oliver 《Plant Growth Regulation》2010,62(3):293-302
The moss Physcomitrella patens is becoming the model of choice for functional genomic studies at the cellular level. Studies report that Physcomitrella survives moderate osmotic and salt stress, and that desiccation tolerance can be induced by exogenous ABA. Our goal was to
quantify the extent of dehydration tolerance in wild type moss and to examine the nature of cellular damage caused by desiccation.
We exposed Physcomitrella to humidities that generate water potentials from −4 (97% RH) to −273 MPa (13% RH) and monitored water loss until equilibrium.
Water contents were measured on a dry matter basis to determine the extent of dehydration because fresh weights (FW) were
found to be variable and, therefore, unreliable. We measured electrolyte leakage from rehydrating moss, assessed overall regrowth,
and imaged cells to evaluate their response to drying and rehydration. Physcomitrella did not routinely survive water potentials <−13 MPa. Upon rehydration, moss dried to water contents >0.4 g g dm−1 maintained levels of leakage similar to those of hydrated controls. Moss dried to lower water contents leaked extensively,
suggesting that plasma membranes were damaged. Moss protonemal cells were shrunken and their walls twisted, even at −13 MPa.
Moss cells rehydrated after drying to −273 MPa failed to re-expand completely, again indicating membrane damage. ABA treatment
elicited tolerance of desiccation to at least −273 MPa and limited membrane damage. Results of this work will form the basis
for ongoing studies on the functional genomics of desiccation tolerance at the cellular level. 相似文献
15.
Summary
Selaginella lepidophylla, the resurrection plant, curls dramatically during desiccation and the hypothesis that curling may help limit bright light-induced damage during desiccation and rehydration was tested under laboratory conditions. Restraint of curling during desiccation at 25° C and a constant irradiance of 2000 mol m–2 s]t-1 significantly decreased PSII and whole-chain electron transport and the Fv/Fm fluorescence yield ratio following rehydration relative to unrestrained plants. Normal curling during desiccation at 37.5°C and 200 mol m–2 s–1 irradiance did not fully protect against photoinhibition or chlorophyll photooxidation indicating that some light-induced damage occurred early in the desiccation process before substantial curling. Photosystem I electron transport was less inhibited by high-temperature, high-irradiance desiccation than either PSII or whole-chain electron transport and PSI was not significantly affected by restraint of curling during desiccation at 25°C and high irradiance. Previous curling also helped prevent photoinhibition of PSII electron transport and loss of whole-plant photosynthetic capacity as the plants uncurled during rehydration at high light. These results demonstrate that high-temperature desiccation exacerbated photoinhibition, PSI was less photoinhibited than PSII or whole-chain electron transport, and stem curling ameliorated bright light-induced damage helping to make rapid recovery of photosynthetic competence possible when the plants are next wetted. 相似文献
16.
Abstract
In the absence of inhibitory concentrations of copper, the photoautotrophic growth of Chlorella vulgaris INETI58C at 27°C exhibited a higher specific growth rate and reached a higher maximal concentration of biomass, under irradiance
of 150 W m−2, compared with 100 W m−2. However, when the mineral growth medium was supplemented with CuSO4 (range 40–80 μM), algal growth was significantly affected at the higher light intensity. In the presence of Cu2+, the increase in dry biomass was uncoupled from the increase in cell concentration since more than 16 autospores gathered
together, inside the enlarged mother cell, suggesting that copper arrested the normal bursting of the mother cell wall. At
the higher irradiance, growth medium supplementation with 80 μM of CuSO4 led to bleaching of photosynthetic pigments. No growth was observed, while, under the lower irradiance, growth was only slightly
inhibited. Results clearly showed that copper toxicity to growth of C. vulgaris was strongly influenced by light intensity. Higher light intensity elicits lethal or sublethal Cu2+ damage at concentrations lower than the threshold level for damage at lower light intensities. Cu2+ may elicit lethal or sublethal light damage at irradiances lower than the threshold level for unpolluted aquatic systems.
Received: 17 January 1997; Accepted 15 April 1997 相似文献
17.
Christopher M. Finelli Brian S. T. Helmuth N. Dean Pentcheff David S. Wethey 《Coral reefs (Online)》2006,25(1):47-57
Recent studies indicate that the incidence and persistence of damage from coral reef bleaching are often highest in areas of restricted water motion, and that resistance to and recovery from bleaching is increased by enhanced water motion. We examined the hypothesis that water motion increases the efflux of oxygen from coral tissue thereby reducing oxidative stress on the photosynthetic apparatus of endosymbiotic zooxanthellae. We experimentally exposed colonies of Montastrea annularis and Agaricia agaricites to manipulations of water flow, light intensity, and oxygen concentration in the field using a novel mini-flume. We measured photosynthetic efficiency using a pulse amplitude modulated fluorometer to test the short-term response of corals to our manipulations. Under normal oxygen concentrations, A. agaricites showed a significant 8% increase in photosynthetic efficiency from 0.238 (± 0.032) in still water to 0.256 (± 0.037) in 15 cm s−1 flow, while M. annularis exhibited no detectable change. Under high-ambient oxygen concentrations, the observed effect of flow on A. agaricites was reversed: photosynthetic efficiencies showed a significant 11% decrease from 0.236 (± 0.056) in still water to 0.211 (± 0.048) in 15 cm s−1 flow. These results support the hypothesis that water motion helps to remove oxygen from coral tissues during periods of maximal photosynthesis. Flow mitigation of oxidative stress may at least partially explain the increased incidence and severity of coral bleaching in low flow areas and observations of enhanced recovery in high-flow areas. 相似文献
18.
Nair S. Yokoya Orlando NecchiJr. Aline P. Martins Suzana F. Gonzalez Estela M. Plastino 《Journal of applied phycology》2007,19(3):197-205
The phycoerythrin-deficient strain (green phenotype) of Hypnea musciformis (Rhodophyta) originated from a green branch, which had arisen as a spontaneous mutation in a wild plant (brown phenotype)
collected from the Brazilian coast. The present study describes the growth responses to irradiance, photoperiod and temperature
variations, pigment contents, and photosynthetic characteristics of the brown and green strains of H. musciformis. The results showed that growth rates increased as a function of irradiance (up to 40 μmol photons m−2 s−1) but, with further increase in irradiance (from 40 to 120 μmol photons m−2 s−1), became light-saturated and remained almost unchanged. The highest growth rates of the brown and green strains were observed
in temperatures of 20–25°C under long (14:10 h LD) and short (10:14 h LD) photoperiods. The brown strain had higher growth
rates than the green strain in the short photoperiod, which could be related to the high concentrations of phycobiliproteins.
Phycoerythrin was not detected in the green strain. The brown strain had higher concentrations of allophycocyanin and phycoerythrin
in the short photoperiod while the green strain had higher concentrations of phycocyanin. The brown strain presented higher
photosynthetic efficiency (α), and lower saturation parameter (Ik) and compensation irradiance (Ic) than the green strain. The brown strain exhibited the characteristics of shade-adapted plants, and its higher value of photosynthetic
efficiency could be attributed to the higher phycoerythrin concentrations. Results of the present study indicate that both
colour strains of H. musciformis could be selected for aquaculture, since growth rates were similar (although in different optimal light conditions), as the
green strain seems to be adapted to higher light levels than the brown strain. Furthermore, these colour strains could be
a useful experimental system to understand the regulation of biochemical processes of photosynthesis and metabolism of light-harvesting
pigments in red algae. 相似文献
19.
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
20.
Abies faxoniana is a key species in reforestation processes in the southeast of the Qinghai-Tibetan Plateau of China. The changes in growth,
photosynthesis and nutrient status of A. faxoniana seedlings exposed to enhanced ultraviolet-B (UV-B), nitrogen supply and their combination were investigated. The experimental
design included two levels of UV-B treatments (ambient UV-B, 11.02 KJ m−2 day−1; enhanced UV-B, 14.33 KJ m−2 day−1) and two nitrogen levels (0; 20 g N m−2). The results indicated that: (1) enhanced UV-B significantly caused a marked decline in growth parameters, net photosynthetic
rate (Pn), photosynthetic pigments and F
v/F
m, (2) supplemental nitrogen supply increased the accumulation of total biomass, Pn, photosynthetic pigments and F
v/F
m under ambient UV-B, whereas supplemental nitrogen supply reduced Pn, and not affect biomass under enhanced UV-B, (3) enhanced
UV-B or nitrogen supply changed the concentration of nutrient elements of various organs. 相似文献