共查询到20条相似文献,搜索用时 15 毫秒
1.
In transgenic (TG) tomato (Lycopersicon esculentum Mill.) overexpressed ω-3 fatty acid desaturase gene (LeFAD7) was identified, which was controlled by the cauliflower mosaic virus 35S promoter and induced increased contents of unsaturated
fatty acids in thylakoid membrane. Under chilling stress at low irradiance (4 °C, 100 μmol m−2 s−1) TG plants with higher linolenic acids (18: 3) content maintained a higher O2 evolution rate, oxidizable P700 content, and maximal photochemical efficiency (Fv/Fm) than wild type (WT) plants. Low temperature treatment for 6 h resulted in extensive changes of chloroplast ultrastructure:
in WT plants most chloroplasts became circular, the number of amyloids increased, appressed granum stacks were dissolved,
grana disappeared, and the number of grana decreased, while only a few grana were found in leaves of TG plants. Hence the
overexpression of LeFAD7 could increase the content of 18: 3 in thylakoid membrane, and this increase alleviated the photoinhibition of photosystem
(PS) 1 and PS2 under chilling at low irradiance. 相似文献
2.
Over-expression of chloroplastic glycerol-3-phosphate acyltransferase gene (LeGPAT) increased unsaturated fatty acid contents in phosphatidylglycerol (PG) of thylakoid membrane in tomato. The effect of this
increase on the xanthophyll cycle and chloroplast antioxidant enzymes was examined by comparing wild type (WT) tomato with
the transgenic (TG) lines at chilling temperature (4 °C) under low irradiance (100 μmol m−2 s−1). Net photosynthetic rate and the maximal photochemical efficiency of photosystem (PS) 2 (Fv/Fm) in TG plants decreased more slowly during chilling stress and Fv/Fm recovered faster than that in WT plants under optimal conditions. The oxidizable P700 in both WT and TG plants decreased
during chilling stress under low irradiance, but recovered faster in TG plants than in the WT ones. During chilling stress,
non-photochemical quenching (NPQ) and the de-epoxidized ratio of xanthophyll cycle in WT plants were lower than those of TG
tomatoes. The higher activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in TG plants resulted in the
reduction of O2
−· and H2O2 contents during chilling stress. Hence the increase in content of unsaturated fatty acids in PG by the over-expression of
LeGPAT could alleviate photoinhibition of PS2 and PS1 by improving the de-epoxidized ratio of xanthophyll cycle and activities of
SOD and APX in chloroplast. 相似文献
3.
Changes in the conformation of spinach thylakoid membranes were monitored in 5-doxyl stearic acid (SAL)-treated thylakoid
membranes in the presence of various anions (Cl−, Br−, I−, NO2
−, SO4
2−, PO4
3−). The presence of anions made the thylakoid membrane more fluid. The extent of change in membrane fluidity differed with
different anion and was reversible. 相似文献
4.
The Susceptibility of Cucumber and Sweet Pepper to Chilling Under Low Irradiance is Related to Energy Dissipation and Water-Water Cycle 总被引:23,自引:4,他引:19
The photoprotection of energy dissipation and water-water cycle were investigated by comparing chilling sensitivity of photosystems
2 (PS2) and 1 (PS1) in two chilling-sensitive plants, cucumber and sweet pepper, upon exposure to 4 °C under low irradiance
(100 μmol m−2 s−1) for 6 h. During chilling stress, the maximum photochemical efficiency of PS2 (Fv/Fm) decreased only slightly in both plants, but the oxidisable P700 decreased markedly, which indicated that PS1 was more sensitive
to chilling treatment under low irradiance than PS2. Sweet pepper leaves had lower Fv/Fm, higher non-photochemical quenching (NPQ), and higher oxidisable P700 during chilling stress. Activity of superoxide dismutase
(SOD) and ascorbate peroxidase (APX) in cucumber leaves was higher, but APX activity decreased apparently compared to that
at room temperature. The productions of active oxygen species (H2O2, O2
−) increased in both plants, faster in cucumber leaves than in sweet pepper leaves. In sweet pepper leaves, a stronger de-epoxidation
of the xanthophyll cycle pigments, a higher NPQ could act as a major protective mechanism to reduce the formation of active
oxygen species during stress. Thus sensitivity of both plants to chilling under low irradiance was dominated by the protective
mechanisms between PS1 and PS2, especially the energy dissipation and the water-water cycle.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
Malaysia is the world’s leading producer of palm oil products that contribute US$ 7.5 billion in export revenues. Like any
other agro-based industries, it generates waste that could be utilized as a source of organic nutrients for microalgae culture.
Present investigation delves upon Isochrysis sp. culture in POME modified medium and its utilization as a supplement to Nanochloropsis sp. in rotifer cultures. The culture conditions were optimized using a 1 L photobioreactor (Temp: 23°C, illumination: 180 ∼ 200 μmol
photons m−2s−1, n = 6) and scaled up to 10 L outdoor system (Temp: 26–29°C, illumination: 50 ∼ 180 μmol photons m−2s−1, n = 3). Algal growth rate in photobioreactor (μ = 0.0363 h−1) was 55% higher compared to outdoor culture (μ = 0.0163 h−1), but biomass production was 1.3 times higher in outdoor culture (Outdoor = 91.7 mg m−2d−1; Photobioreactor = 69 mg m−2d−1). Outdoor culture produced 18% higher lipid; while total fatty acids (FA) was not significantly affected by the change in
culture systems as both cultures yield almost similar concentrations of fatty acids per gram of sample (photobioreactor = 119.17 mg
g−1; outdoor culture = 104.50 mg g−1); however, outdoor cultured Isochrysis sp. had 26% more polyunsaturated fatty acids (PUFAs). Rotifers cultured in Isochrysis sp./ Nanochloropsis sp. (1:1, v/v) mixture gave similar growth rate as 100% Nanochoropsis sp. culture (μ = 0.40 d−1), but had 45% higher counts of rotifers with eggs (t = 7, maximum). The Isochrysis sp. culture successfully lowered the nitrate (46%) and orthophosphate (83%) during outdoor culture. 相似文献
6.
Comparative study about the salt-induced oxidative stress and lipid composition has been realised in primary root tissues
for two varieties of maize (Zea mays L.) in order to evaluate their responses to salt stress. The root growth, root water content (WC), hydrogen peroxide (H2O2) generation, lipid peroxidation, membrane stability index and the changes in the profile of fatty acids composition were
investigated. Salinity impacts in term of root growth, water content, H2O2 generation, lipid peroxidation and membrane destabilisation were more pronounced in primary roots of Aristo than in those of Arper indicating more sensitivity of the first variety. It was confirmed by gas chromatography that the composition of fatty acids
in roots of both varieties was constituted mainly by 16:0 and 18:0 as major saturated fatty acids and 18:1ω9, 18:2ω6 and 18:3ω3
as major unsaturated fatty acids. Total lipid extracts from the roots of both varieties showed that the lipid saturation level
increased under salt stress, notwithstanding the increased proportion of polyunsaturated fatty acids. The changes in lipid
saturation being predominantly due to decreases in oleic acid (18:1ω9) and increases in palmitic acid (16:0). However, Arper root extracts contained a lower proportion of saturated lipids than Aristo. The enhanced proportion of highly polyunsaturated fatty acids especially linolenic and eicosapentaenoic acids was considered
to be the characteristic of the relatively salt tolerance in Arper roots. 相似文献
7.
Janusz Ko cielniak Władysław Filek Jolanta Biesaga-Ko cielniak 《Acta Physiologiae Plantarum》2006,28(2):149-158
The effects of drought on photochemical efficiency of PSII in leaves of 22 hybrids of Festuca pratensis × Lolium multiflorum and Festuca pratensis × Lolium perenne and of Festuca pratensis cv. Skra were investigated. A significant decrease of electron transport efficiency (about 25%) in PSII (ΦPSII) was not found before 9 days of seedling growth in hydroponics with water potential (Ψw) equal to −0.8 MPa (simulated “soil drought”). The decrease of ΦPSII was similarly related to that of excitation energy capture by open PSII reaction centre (Fv’/Fm’) and also to the decrease
of the proportion of oxidized to reduced QA (photochemical fluorescence quenching, qp). According to the drought prolongation, variation of all parameters of fluorescence between genotypes significantly increased.
The seedlings of some genotypes were able to recover electron transport efficiency in PSII after increasing water potential
in nutrient solution (removing the “soil drought”).
When plants grew in containers with soil and 4 genotypes with the highest sensitivity of electron transport to drought (S)
as well as 4 genotypes with the highest tolerance (T) were compared 17 days after watering ceased, Ψw in leaves considerably decreased, but the differences between S and T genotypes were often not significant in this respect.
The differences between S and T genotypes, as values of Fv/Fm were concerned, also appeared small (about 5%), similarly as
that of Fv’/Fm’ (5%), qp (12%) and ΦPSII (about 15%).
Drought stress increased non-photochemical quenching of chlorophyll fluorescence (NPQ) 15 to 47% and this could protect the
PSII reaction centres from damages because of energy excess. The increase of NPQ was not closely connected with drought resistance
of plants because it was similar in some genotypes tolerant to dehydration as well as in sensitive ones.
The results of the experiments suggest that resources of genetic variability in Festulolium may be sufficient for revealing differences between genotypes on the basis of measurement of chlorophyll a fluorescence, as far as their tolerance to soil drought is concerned. As the tolerance of PSII against drought is high, the
determinations of fluorescence should be performed rather under severe stress. Such methods seem to be useful for selection
of genotypes with high drought tolerance as well as with the ability to at least partial repairing of PSII after drought. 相似文献
8.
The marine picocyanobacterium Synechococcus sp. WH8102 was submitted to ultraviolet (UV-A and B) radiations and the effects of this stress on reaction center II and
phycobilisome integrity were studied using a combination of biochemical, biophysical and molecular biology techniques. Under
the UV conditions that were applied (4.3 W m−2 UV-A and 0.86 W m−2 UV-B), no significant cell mortality and little chlorophyll degradation occurred during the 5 h time course experiment. However,
pulse amplitude modulated (PAM) fluorimetry analyses revealed a rapid photoinactivation of reaction centers II. Indeed, a
dramatic decrease of the D1 protein amount was observed, despite a large and rapid increase in the expression level of the
psbA gene pool. Our results suggest that D1 protein degradation was accompanied (or followed) by the disruption of the N-terminal
domain of the anchor linker polypeptide LCM, which in turn led to the disconnection of the phycobilisome complex from the thylakoid membrane. Furthermore, time course
analyses of in vivo fluorescence emission spectra suggested a partial dismantling of phycobilisome rods. This was confirmed
by characterization of isolated antenna complexes by SDS-PAGE and immunoblotting analyses which allowed us to locate the disruption
site of the rods near the phycoerythrin I—phycoerythrin II junction. In addition, genes encoding phycobilisome components,
including α-subunits of all phycobiliproteins and phycoerythrin linker polypeptides were all down regulated in response to
UV stress. Phycobilisome alteration could be the consequence of direct UV-induced photodamages and/or the result of a protease-mediated
process. 相似文献
9.
Exogenously-supplied trehalose protects thylakoid membranes of winter wheat from heat-induced damage
The effects of trehalose pretreatment on thylakoid membranes of winter wheat were investigated under heat stress. Under normal
growth conditions, the winter wheat synthesized 502 μg g−1(f.m.) trehalose, which increased to 1250 μg g−1(f.m.) under heat stress and to 1658 μg g−1(f.m.) in trehalose-pretreated seedlings. Under heat stress, proteins in the thylakoid membranes and the photosynthetic capacity
were protected by trehalose pretreatment. Moreover, the electrolyte leakage, contents of malondialdehyde, superoxide anion
and hydrogen peroxide, and lipoxygenase activity in trehalose-pretreated seedlings were lower than in the non-pretreated plants. 相似文献
10.
T. Kashiwagi V. B. Meyer-Rochow K. Nishimura E. Eguchi 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(1):1-8
The ultrastructural state of the crayfish visual membrane is correlated with its fatty acid composition during times of photic
and thermal stress and the period over which the dynamic events occur is investigated. Crayfish kept at 4 °C under constant
darkness contain in their rhabdoms significantly increased amounts of unsaturated fatty acids such as 16:1, 18:1, 20:5, and
22:6 compared with individuals kept at 25 °C. The ratio of unsaturated/saturated fatty acids (UFA/SFA-ratio) amounts to 2.17
in the cold-water- and 1.46 in the warm water-acclimated animals. The visual membranes of crayfish suddenly transferred from
4 °C to 25 °C exhibited ultrastructural modifications such as membrane collapse and disappearance of microvillar dense␣core-filaments
most clearly 3 h post-transfer. Parallel to the structural changes a significant increase in fatty acid 18:0 was observed,
while the amounts of 16:1 and 20:1 decreased. When 4 °C, dark-adapted crayfish were exposed to light alone and not a temperature
increase, only fatty acid 22:6 showed a significant reduction to 10% of its pre-experimental level within 2 h of exposure.
Thereafter, it slowly increased again. In cold water-acclimated crayfish that had been exposed to light of 5000 lx for 3␣weeks
no significant change of the UFA/SFA ratio was observed, although fatty acid species 18:0, 20:4, and 20:5 had increased at
the expense of fatty acids 14:0, 16:0, 16:1, 18:1, 20:1, and 22:6. The total amount of fatty acids, however, had become significantly
smaller (from 0.058 ng g−1 body weight in the dark-adapted to 0.048 ng g−1 in the light-adapted crayfish). Morphologically the rhabdom volume had decreased by approx. 20%, but ultrastructurally rhabdom
microvilli remained almost unchanged. The amount of peroxidized lipids in the retina following irradiation with bright white
light in the cold-adapted crayfish fell during the first 2 h of exposure from 0.4 nmol g−1 to 0.32 nmol g−1, but after 12 h of exposure had reached a level of 0.48 nmol g−1. Greatest structural abnormalities to the visual membranes occurred when dark-adapted, cold-acclimated crayfish were suddenly
subjected to bright light and an increase in water temperature. Under such conditions the microvillar arrangement was disrupted
and membrane collapse and disappearance of core-filaments were apparent. Our results provide evidence that the fatty acid
composition of the membranes determines to a considerable extent the structural integrity of the photoreceptor, but that it
is too simplistic a model to think that peroxidation of membrane lipids alone is responsible for the disintegration of the
photoreceptive membranes in the crayfish eye following exposure to bright light.
Accepted: 4 July 1996 相似文献
11.
Huguette Sallanon Monique Berger Catherine Genoud Alain Coudret 《In vitro cellular & developmental biology. Plant》1998,34(2):169-172
Summary MicropropagatedRosa hybrida plantlets were simultaneously rooted and acclimatized under 100 and 200 μmol m−2 s−1 light for 2 wk. At the end of the first week of acclimatization, the plantlets were transferred onto a low water potential
medium (from −0.06 MPa to −0.3 MPa). Dry weight was decreased by increased hight and low water potential. Photoinhibition
of photosynthesis, expressed as a decrease in Fv/Fm ratio and ΦPSII and an increase in 1 −qp, occurred in plants grown under
200 μmol m−2 s−1. When high light (200 μmol m−2 s−1) and water stress were applied simultaneously, their effects on chlorophyll fluorescence parameters depended on stress duration;
after 1 d of water stress, photoinhibition was more pronounced; after 7 d of stress, Fv/Fm ratio and ΦPSII were higher than
after 1 d of stress; photoinhibition was reduced. This suggests that after a 1-d stress, the effect of water stress alone
included a superimposed effect of photoinhibition to which the water-stressed plants were sensitized; after 7 d, plantlets
had adapted to water stress. The photoprotective effects under high light might result in energy dissipative mechanisms linked
to photochemical and nonphotochemical quenching other than CO2 fixation. 相似文献
12.
To investigate damaging mechanisms of chilling and salt stress to peanut (Arachis hypogaea L.) leaves, LuHua 14 was used in the present work upon exposure to chilling temperature (4°C) accompanied by high irradiance
(1,200 μmol m−2 s−1) (CH), salt stress accompanied by high irradiance (1,200 μmol m−2 s−1) (SH), and high-irradiance stress (1,200 μmol m−2 s−1) at room temperature (25°C) (NH), respectively. Additionally, plants under low irradiance (100 μmol m−2 s−1) at room temperature (25°C) were used as control plants (CK). Relative to CK and NH treatments, both the maximal photochemical
efficiency of PSII (Fv/Fm) and the absorbance at 820 nm decreased greatly in peanut leaves under CH and SH stress, which indicated that severe photoinhibition
occurred in peanut leaves under such conditions. Initial fluorescence (Fo), 1 − qP and nonphotochemical quenching (NPQ) in peanut leaves significantly increased under CH- and SH stress. Additionally, the
activity of superoxide dismutase (SOD), one of the key enzymes of water-water cycle, decreased greatly, the accumulation of
malondialdehyde (MDA) and membrane permeability increased. These results suggested that damages to peanut photosystems might
be related to the accumulation of reactive oxygen species (ROS) induced by excess energy, and the water-water cycle could
not dissipate energy efficiently under the stress of CH and SH, which caused the accumulation of ROS greatly. CH and SH had
similar damaging effects on peanut photosystems, except that CH has more severe effects. All the results showed that CH- and
SH stress has similar damaging site and mechanisms in peanut leaves. 相似文献
13.
Yaşar Durmaz Margarida Monteiro Narcisa Bandarra Şevket Gökpinar Oya Işik 《Journal of applied phycology》2007,19(3):223-227
Porphyridium cruentum was grown in 10 L batch culture at 18°C, pH 8.0 and 28‰ salinity. The cells were harvested in the stationary phase and the
fatty acid composition analysed by GC and tocopherol content by HPLC. A total of 14 fatty acids were identified including
saturated fatty acids (13:0, 14:0, 14:0 iso, 15:0, 16:0, 16:0iso) and monounsaturated fatty acids (MUFAs; 16:1(n-7), 18:1(n-7),
18:1(n-9). Polyunsaturated fatty acids (PUFAs) were the predominant fatty acids detected, reaching 43.7% of total fatty acids
in the stationary phase of culture. Among the PUFAs, eicosapentaenoic acid (EPA, 20:5(n-3)) was dominant (25.4%), followed
by 12.8% arachidonic acid (AA, 20:4(n-6)). α-Tocopherol and γ-tocopherol contents were 55.2 μg g−1 dry weight and 51.3 μg g−1 dry weight respectively. 相似文献
14.
Changes in Unsaturated Levels of Fatty Acids in Thylakoid PSII Membrane Lipids During Chilling-induced Resistance in Rice 总被引:2,自引:0,他引:2
Su-Qin Zhu Chun-Mei Yu Xin-Yan Liu Ben-Hua Ji De-Mao Jiao 《植物学报(英文版)》2007,49(4):463-471
Temperature is one of the abiotic factors limiting growth and productivity of plants. In the present work, the effect of low non‐freezing temperature, as an inducer of “chilling resistance”, was studied in three cultivars of rice (Oryza sativa L.), japonica cv. 9516 (j‐9516), the two parental lines of superhigh‐yield hybrid rice between subspecies, Peiai/E32 (ji‐PE), and the traditional indica hybrid rice Shanyou 63 (i‐SY63). Leaves of chill‐treated rice showed chilling‐induced resistance, as an increase of their low‐temperature tolerance was measured using chlorophyll fluorescence measurements, revealing a change in photosystem II (PSII) efficiency. After 5 d of exposure to 11°C under low light (100 μmol m‐2 s‐1), levels of unsaturated fatty acids in PSII thylakoid membrane lipids decreased during the initial 1‐2 d, then increased slowly and reached 99.2%, 95.3% and 90.1% of the initial value (0 d) in j‐9516, ji‐PE and i‐SY63, respectively, on the fifth day. However, under medium light (600 μmol m‐2 s‐1), all cultivars experienced similar substantial photoinhibition, which approached steady state levels after a decline in levels of unsaturated fatty acids in PSII thylakoid membrane lipids to about 57.1%, 53.8% and 44.5% of the initial values (0 d) in j‐9516, ji‐PE and I‐SY63 on the fifth day. Under either chilling‐induced resistance (the former) or low temperature photoinhibition (the latter) conditions, the changes of other physiological parameters such as D1 protein contents, electron transport activities of PSII (ETA), Fv/Fm, xanthophyl cycle activities expressed by DES (deepoxide state) were consistent with that of levels of unsaturated fatty acids in PSII thylakoid membrane lipids. So there were negative correlations between saturated levels of fatty acids (16:1(3t), 16:0, 18:0), especially the 16:1(3t) fatty acid on thylakoid membrane and other physiological parameters, such as D1 protein contents, ETA and (A+Z)/(A+V+Z). A specific role of desaturation of fatty acids and the photoprotective pigments of the xanthophyl cycle, leading to an acclimation response in thylakoid membrane lipids may be involved. We conclude that chilling‐induced resistance is accelerated by the unsaturation of thylakoid membranes, and the ability of rice plants to cold‐harden can be enhanced by genetic engineering. 相似文献
15.
Summary. As the outermost boundary of the cell, the plasma membrane plays an important role in determining the stress resistance of
organisms. To test this concept in a cryophyte, we analyzed alterations of several components in plasma membranes isolated
from suspension-cultured cells of Chorispora bungeana Fisch. & C.A. Mey in response to treatment at 0 and −4 °C for 192 h. When compared with the controls growing at 25 °C, both
the membrane permeability and fluidity showed recovery after the initial impairment. Linolenic acid and membrane lipid unsaturation
increased by about 0.8-fold following cold treatments, although the kinetics of the increase varied with the temperatures
examined. During the treatments, the plasma membrane H+-ATPase (EC 3.6.1.3) activity increased by 78.06% at 0 °C and 100.47% at −4 °C. However, the plasma membrane NADH oxidase
(EC 1.6.99.3) activity only decreased when exposed to a lower temperature (−4 °C), and remained at 63.93% after being treated
for 192 h. After the treatments, the physical properties of the plasma membranes of suspension-cultured cells, especially
the −4 °C treated cells, were similar to those in the wild plants. These findings indicate that the specific mechanism of
cold resistance of C. bungeana is tightly linked with the rapid and flexible regulation of membrane lipids and membrane-associated enzymes, which ensure
the structural and functional integrity of the plasma membrane that is essential for withstanding low temperature.
Correspondence: Lizhe An, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences,
Lanzhou 730000, People’s Republic of China. 相似文献
16.
Genetic engineering of the biosynthesis of glycinebetaine enhances thermotolerance of photosystem II in tobacco plants 总被引:1,自引:0,他引:1
Genetically engineered tobacco (Nicotiana tabacum L.) with the ability to accumulate glycinebetaine was established. The wild type and transgenic plants were exposed to heat
treatment (25–50°C) for 4 h in the dark and under growth light intensity (300 μmol m−2 s−1). The analyses of oxygen-evolving activity and chlorophyll fluorescence demonstrated that photosystem II (PSII) in transgenic
plants showed higher thermotolerance than in wild type plants in particular when heat stress was performed in the light, suggesting
that the accumulation of glycinebetaine leads to increased tolerance to heat-enhanced photoinhibition. This increased tolerance
was associated with an improvement on thermostability of the oxygen-evolving complex and the reaction center of PSII. The
enhanced tolerance was caused by acceleration of the repair of PSII from heat-enhanced photoinhibition. Under heat stress,
there was a significant accumulation of H2O2, O2− and catalytic Fe in wild type plants but this accumulation was much less in transgenic plants. Heat stress significantly
decreased the activities of catalase, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monodehydroascorbate
reductase in wild type plants whereas the activities of these enzymes either decreased much less or maintained or even increased
in transgenic plants. In addition, heat stress increased the activity of superoxide dismutase in wild type plants but this
increase was much greater in transgenic plants. Furthermore, transgenic plants also showed higher content of ascorbate and
reduced glutathione than that of wild type plants under heat stress. The results suggest that the increased thermotolerance
induced by accumulation of glycinebetaine in vivo was associated with the enhancement of the repair of PSII from heat-enhanced
photo inhibition, which might be due to less accumulation of reactive oxygen species in transgenic plants. 相似文献
17.
Effects of short-term heat stress on oxidative damage and responses of antioxidant system in Lilium longiflorum 总被引:2,自引:0,他引:2
This paper aims to determine the changes in reactive oxygen species (ROS) and the responses of the lily (Lilium longiflorum L.) antioxidant system to short-term high temperatures. Plants were exposed to three levels of heat stress (37°C, 42°C, 47°C)
for 10 h when hydrogen peroxide (H2O2) and superoxide (O2−) production rate along with membrane injury indexes, and changes in antioxidants were measured. Compared with the control
(20°C), electrolyte leakage and MDA concentration varied slightly after 10 h at 37°C and 42°C, while increased significantly
at 47°C. During 10 h at 37°C and 42°C, antioxidant enzyme activities, such as SOD, POD, CAT, APX and GR, were stimulated and
antioxidants (AsA and GSH concentrations) maintained high levels, which resulted in low levels of O2− and H2O2 concentration. However, after 10 h at 47°C, SOD, APX, GR activities and GSH concentration were similar to the controls, while
POD, CAT activities and AsA concentration decreased significantly as compared with the control, concomitant with significant
increase in O2− and H2O2 concentrations. In addition, such heat-induced effects on antioxidant enzymes were also confirmed by SOD and POD isoform,
as Cu/ZnSOD maintained high stability under heat stress and the intensity of POD isoforms reduced with the duration of heat
stress, especially at 47°C. It is concluded that in lily plants, the oxidative damage induced by heat stress was related to
the changes in antioxidant enzyme activities and antioxidants. 相似文献
18.
K. Muthuchelian C. Murugan R. Harigovindan N. Nedunchezhian A. Premkumar G. Kulandaivelu 《Biologia Plantarum》1996,38(2):245-251
The detrimental effect of NaCl was found at the oxidation site of photosystem 2 (PS2). An impairment of PS2 was caused by
damage of the oxygen evolving polypeptides (33, 23 and 20 kDa) of thylakoid membranes as well as by changes in the unsaturated
and saturated fatty acids. Application of triacontanol, TRIA (1 mg kg-1) ameliorated the effect of NaCl and promoted the ratio of unsaturated to saturated fatty acids, the rate of14CO2 fixation and the activity of ribulose 1,5-bis-phosphate carboxylase.
We thank Prof. T.M. Haridasan for providing laboratory fucilities. Financial support from the Society for Social Forestry
Research and Development, Tamilnadu is gratefully acknowledged. 相似文献
19.
Long-term (30 d) effects of 100, 200, 300, and 400 mM NaCl on photosystem 2 (PS 2)-mediated electron transport activity and
content of D1 protein in the thylakoid membranes of chrysanthemum (Dendranthema grandiflorum) cultured in vitro at low irradiance 20 μmol(photon) m−2 s−1 were investigated. 100 mM NaCl increased contents of chlorophylls (Chl) a and b, carotenoids (Car; xanthophylls + carotenes), and the ratio of Chl a/b, and Car/Chl a+b. However, further increase in NaCl concentration led to the significant reduction in the contents of Chl a, and Chl b, and increase in the ratio of Chl a/b and Car/Chl a+b. NaCl treatment decreased the PS 2-mediated electron transport activity and contents of various thylakoid membrane polypeptides
including D1 protein. 相似文献
20.
The function of chloroplast ferredoxin quinone reductase (FQR)-dependent flow was examined by comparing a wild type tobacco
and a tobacco transformant (ΔndhB) in which the ndhB gene had been disrupted with their antimycin A (AA)-fed leaves upon exposure to chilling temperature (4 °C) under low irradiance
(100 μmol m−2 s−1 photon flux density). During the chilling stress, the maximum photochemical efficiency of photosystem (PS) 2 (Fv/Fm) decreased markedly in both the controls and AA-fed leaves, and P700+ was also lower in AA-fed leaves than in the controls, implying that FQR-dependent cyclic electron flow around PS1 functioned
to protect the photosynthetic apparatus from chilling stress under low irradiance. Under such stress, non-photochemical quenching
(NPQ), particularly the fast relaxing NPQ component (qf) and the de-epoxidized ratio of the xanthophyll cycle pigments, (A+Z)/(V+A+Z), formed the difference between AA-fed leaves
and controls. The lower NPQ in AA-fed leaves might be related to an inefficient proton gradient across thylakoid membranes
(ΔpH) because of inhibiting an FQR-dependent cyclic electron flow around PS1 at chilling temperature under low irradiance. 相似文献