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1.
When Porphyridium cruentum cells were illuminated with high fluence rate between 1900 and 4800 mol photons m-2s-1, a decrease in the photosynthetic activity of the cells was observed. Within the time frame of 20 min, and under the fluence rates studied, the sum of photons to be absorbed by cells (mg of chlorophyll (Chl), sufficient to initiate photoinhibition was calculated to be 9235.8 mol. The minimal specific light absorption rate to initiate photoinhibition in P. cruentum ranges between 2.29 and 4.26 mol photons s-1 mg-1 chl.a. There was a linear relationship between the specific rate of photoinhibition and the specific light absorption rate. A photon number of 2.56×104 mol mg-1 chl.a photoinhibited photosynthesis instantaneously. At 15°C, no photoinhibitory effect was observed at 2300 mol photons m-2 s-1 even after 45 min of illumination. At the other extreme of 35°C, 84% inhibition of photosynthetic activity was observed within 10 min of exposure to 2300 mol photons m-2 s-1. Between 20 and 30°C, the photoinhibitory effect was comparable. Photoinhibited P. cruentum cells recovered readily when transferred to low light (90 mol photons m-2 s-1) and darkness, and the specific rate of recovery was independent of the light intensity to which the cells were exposed, during the photoinhibitory treatment.Abbreviations Chlorophyll
QL, specific light absorption rate
Publication No. 28 of the Microalgal Biotechnology Laboratory 相似文献
2.
ΔpH-dependent chlorophyll fluorescence quenching indicating a mechanism of protection against photoinhibition of chloroplasts 总被引:1,自引:0,他引:1
Intact isolated spinach chloroplasts were subjected to photoinhibitory conditions (high light and lack of CO2). Photoinhibition of the electron transport system was considerably diminished when the chloroplasts were in a low-fluorescent state related to a high proton gradient across the thylakoid membranes, as compared to a high-fluorescent state in which ΔpH-dependent fluorescence quenching was abolished by addition of uncouplers. The hypothesis is discussed that in chloroplasts exposed to excess light, photoinhibition is partly prevented by increased thermal dissipation of excitation energy, as expressed by ΔpH-dependent (‘energy-dependent’) chlorophyll a fluorescence quenching. 相似文献
3.
Wild-type tobacco plants (Nicotiana tabacum L. cv. Petit Havanna line SR1) and plants transformed with full-length alfalfa ferritin cDNA with the chloroplast transit peptide under the control of a Rubisco small subunit gene promoter (C3 and C8) were cold-treated at 0 degrees C with continuous light (250mumolm(-2)s(-1)). These transgenic plants had higher chlorophyll content and higher F(v)/F(m) chlorophyll-a fluorescence induction parameters than wild-type plants after 2 or 3d of cold treatment in C3 and C8 transgenic plants, respectively. Thermoluminescence studies on the high-temperature bands suggest that these plants suffered less oxidative damage in comparison to the wild-type genotype. The present experiments provide evidence that transgenic tobacco lines overexpressing alfalfa ferritin, which is accumulated in the chloroplasts, may show higher tolerance to various stress factors, generating ROS including low temperature-induced photoinhibition. 相似文献
4.
5.
Susceptibility of a moss,Ceratodon purpureus (Hedw.) Brid., to photoinhibition and subsequent recovery of the photochemical efficiency of PSII was studied in the presence
and absence of the chloroplast-encoded protein-synthesis inhibitor lincomycin.Ceratodon had a good capacity for repairing the damage to PSII centers induced by strong light. Tolerance against photoinhibition was
associated with rapid turnover of the D1 protein, since blocking of D1 protein synthesis more than doubled the photoinhibition
rate measured as the decline in the ratio of variable fluorescence to maximal fluorescence (Fv/Fmax). Under exposure to strong light in the absence of lincomycin a net loss of D1 protein occurred, indicating that the degradation
of damaged D1 protein inCeratodon was rapid and independent of the resynthesis of the polypeptide. The result suggests that synthesis is the limiting factor
in the turnover of D1 protein during photoinhibition of the mossCeratodon. The level of initial fluorescence (Fo) correlated with the production of inactive PSII centers depleted of D1 protein. The higher the Fo level, the more severe was the loss of D1 protein seen in the samples during photoinhibition. Restoration of Fv/Fmax at recovery light consisted of a fast and slow phase. The recovery of fluorescence yield in the presence of lincomycin, which
was added at different times in the recovery, indicated that the chloroplast-encoded protein-synthesis-dependent repair of
damaged PSII centers took place during the fast phase of recovery. Pulse-labelling experiments with [35S]methionine supported the conclusion drawn from fluorescence measurements, since the rate of D1 protein synthesis after photoinhibition
exceeded that of the control plants during the first hours under recovery conditions. 相似文献
6.
Efficient photosynthesis is of fundamental importance for plant survival and fitness. However, in oxygenic photosynthesis, the complex apparatus responsible for the conversion of light into chemical energy is susceptible to photodamage. Oxygenic photosynthetic organisms have therefore evolved several protective mechanisms to deal with light energy. Rapidly inducible non-photochemical quenching (NPQ) is a short-term response by which plants and eukaryotic algae dissipate excitation energy as heat. This review focuses on recent advances in the elucidation of the molecular mechanisms underlying this protective quenching pathway in higher plants. 相似文献
7.
Resistance to photoinhibition of photosystem II and catalase and antioxidative protection in high mountain plants 总被引:7,自引:1,他引:7
In leaves of three alpine high mountain plants, Homogyne alpina, Ranunculus glacialis and Soldanella alpina, both photosystem II (PSII) and the enzyme catalase appeared to he highly resistant to photoinactivation under natural field conditions. While the Dl protein of PSII and catalase have a rapid turnover in light and require continuous new protein synthesis in non-adapted plants, little apparent photoinactivation of PSII or catalase was induced in the alpine plants by translation inhibitors or at low temperature, suggesting that turnover of the Dl protein and catalase was slow in these leaves. In vitro PSII was rapidly inactivated in light in isolated thylakoids from H. alpina and R. glacialis. In isolated intact chloroplasts from R. glacialis, photoinactivation of PSII was slower than in thylakoids. Partially purified catalase from R. glacialis and S. alpina was as sensitive to photoinactivation in vitro as catalases from other sources. Catalase from H. alpina had, however, a 10-fold higher stability in light. The levels of xanthophyll cycle carotenoids, of the antioxidants ascorbate and glulathione, and of the activities of catalase, superoxide dismutase and glutathione reductase were very high in S. alpina, intermediate in H. alpina, but very low in R. glacialis. However, isolated chloroplasts from all three alpine species contained much higher concentrations of ascorbate and glutathione than chloroplasts from lowland plants. 相似文献
8.
Photosynthetica - The aim of this study was to assess the impact of the mitochondrial alternative oxidase (AOX) pathway on energy metabolism in chloroplasts, and evaluate the importance of the AOX... 相似文献
9.
Jin-Hong Kim Jae Sung Kim Byung Chull An Byung Yeoup Chung 《Journal of Plant Biology》2006,49(5):353-357
We studied the radiation-induced stress resistance in red pepper leaves under conditions of low-temperature photoinhibition
or artificially induced photo-oxidative stress. Plants irradiated with 4, 8, or 16-Gy gamma rays were more resistant to both
stress factors than were the controls. However, exposure to a low temperature for 12 h with illumination or photo-oxidative
treatment for 1 h differentially affected the irradiated leaves, although they had similar stress intensities as defined by
their maximal photochemical efficiencies (Fv/Fm). Decreases in Fv/Fm induced by the two stress factors were instead alleviated,
dose-dependently, by as much as 22 to 41% (low temperature) or 14 to 29% (photo-oxidation) in the irradiated groups. In contrast,
non-photochemical quenching (NPQ) and the de-epoxidation state of xanthophyll cycle pigments could not be correlated with
this enhanced stress resistance in the irradiated groups. These results suggest that the adaptive response of plants exposed
to gamma radiation is more effective in protecting against low-temperature photoinhibition than against photo-oxidative stress.
We also discuss here the involvement of antioxidative defense systems for increased resistance against low-temperature photoinhibition
in irradiated red pepper. 相似文献
10.
The mechanisms by which higher plants recognize and respond to sugars are largely unknown. Here, we present evidence that the first enzyme in the hexose assimilation pathway, hexokinase (HXK), acts as a sensor for plant sugar responses. Transgenic Arabidopsis plants expressing antisense hexokinase (AtHXK) genes are sugar hyposensitive, whereas plants overexpressing AtHXK are sugar hypersensitive. The transgenic plants exhibited a wide spectrum of altered sugar responses in seedling development and in gene activation and repression. Furthermore, overexpressing the yeast sugar sensor YHXK2 caused a dominant negative effect by elevating HXK catalytic activity but reducing sugar sensitivity in transgenic plants. The result suggests that HXK is a dual-function enzyme with a distinct regulatory function not interchangeable between plants and yeast. 相似文献
11.
Kitajima S Ueda M Sano S Miyake C Kohchi T Tomizawa K Shigeoka S Yokota A 《Bioscience, biotechnology, and biochemistry》2002,66(11):2367-2375
Depletion of the electron donor ascorbate causes rapid inactivation of chloroplastic ascorbate peroxidase (APX) of higher plants, while cytosolic APX is stable under such conditions. Here we report the cloning of cDNA from Galdieria partita, a unicellular red alga, encoding a novel type of APX (APX-B). The electrophoretic mobility, Km values, kcat and absorption spectra of recombinant APX-B produced in Escherichia coli were measured. Recombinant APX-B remained active for at least 180 min after depletion of ascorbate. The amino-terminal half of APX-B, which forms the distal pocket of the active site, was richer in amino acid residues conserved in chloroplastic APXs of higher plants rather than cytosolic APXs. In contrast, the sequence of the carboxyl-terminal half, which forms the proximal pocket, was similar to that of the cytosolic isoform. The stability of APX-B might be due to its cytosolic isoform-like structure of the carboxyl-terminal half. 相似文献
12.
13.
Jacek Augustyniak Mirosława Dabert Krzysztof Wypijewski 《Acta Physiologiae Plantarum》1997,19(4):561-569
Protective transgenes introduced into plants can be classified as directed against insects, fungi, bacteria or viruses. Mechanisms
by which they protect plants in some cases are relatively simple and understood while in most cases they present only the
field of rapidly progressing investigations. A brief review of the recent concepts of the resistance induced in plants against
viruses by virus-derived transgenes is presented with emphasising the RNA mediated resistance. The RNA mediated resistance
seems to operate in Nicotiana benthamiana plants transformed in our laboratory with cDNA of the PPV CP gene: both translatable and untranslatable versions of the cDNA
made the transformed plants resistant against PPV. The resistant plants contained more than one copy of the transgene. To
protect against insects plants were in our laboratory transformed with potato proteinase inhibitor II gene (PPI-II). The PPI-II
gene expressed in model plants inhibited trypsin activity to an expected level. 相似文献
14.
The stages of the legume-rhizobial symbiosis and nodule structure in various legume plants are briefly reviewed. Modern data on the mechanisms involved in the control of nodule initiation and morphogenesis are considered. 相似文献
15.
Yanykin D. V. Malferrari M. Rapino S. Venturoli G. Semenov A. Yu Mamedov M. D. 《Photosynthesis research》2019,141(2):165-179
Photosynthesis Research - In the present study, we have investigated the effect of hydroxyectoine (Ect-OH), a heterocyclic amino acid, on oxygen evolution in photosystem II (PS II) membrane... 相似文献
16.
Nadezda P. Yurina Georgij V. Karakashev Navasard V. Karapetyan Margarita S. Odintsova 《Photosynthesis research》1991,30(1):15-23
The polypeptide composition of thylakoid membranes of the red alga Cyanidium caldarium was studied by PAGE in the presence of lithium dodecyl sulfate. The thylakoid membranes were shown to contain 65 polypeptides with mol wt from 110 to 10 kDa. PS I isolated from C. caldarium cells is composed of at least 5 components, one of which is the chlorophyll-protein complex with mol wt of 110 kDa typical of higher plants. Cyt f, c
552, b
6 and b
559 were identified. Inhibition of carotenoid biosynthesis with norflurazon caused no changes in the polypeptide composition of thylakoid membranes of the algae grown in dark. The suppression of the biosynthesis rate of some thylakoid polypeptides in the algae grown with norflurazon in light is a result of membrane photodestruction. Thylakoid membranes from C. caldarium cells are more similar in the number of protein components to thylakoid membranes from cells of the cyanobacterium Anacystis nidulans than to those of higher plants (Pisum sativum), which was proved by immune-blotting assays: Thylakoid membranes of the red alga and cyanobacteria contain 28 homologous polypeptides, while thylakoid membranes of the alga and pea, only 15.Abbreviations CD
circular dichroism
- CP
chlorophyll-protein complex
- LDS
lithium dodecyl sulfate
- NF
norflurazon 相似文献
17.
18.
Nitzsche W. 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1983,65(2):171-172
Theoretical and Applied Genetics - Virulence and resistance may act on the same biochemical mechanisms. Because Erwinia-virulence on potato depends on the lysis of cell walls of the host,... 相似文献
19.
In the red alga, Griffithsia pacifica, shoot portions of a plantare positively phototropic and rhizoids are negatively phototropic.We have studied the phototropic response of rhizoids which elongateby tip growth. For 45 min after the beginning of unilateralillumination a rhizoid grows straight, then phototropic curvaturebegins and continues rapidly until the rhizoid is growing awayfrom the light. Curvature is 7080% complete after 3 hr.If the unilateral stimulus is given for a short time (15 min),curvature again begins at 45 min. However, within an additional3045 min the rhizoid stops growing away from the lightand wanders back towards its original direction of growth. Phototropismis elicited by light of wavelengths from 350 nm to 500 nm; inlight of wavelengths above 550 nm, little, if any, responseoccurs.
1Present address: Division of Natural Sciences, University ofCalifornia, Santa Cruz, California 95064, U.S.A. (Received December 10, 1976; ) 相似文献
20.
Leaf discs of the shade plant Tradescantia albiflora Kunth grown at 50 μmol · m?2 · s?1, and the facultative sun/shade plant Pisum sativum L. grown at 50 or 300 μmol · m?2, s?1, were photoinhibited for 4 h in 1700 μmol photons m?2 · s?1 at 22° C. The effects of photoinhibition on the following parameters were studied: i) photosystem II (PSII) function; ii) amount of D1 protein in the PSII reaction centre; iii) dependence of photoinhibition and its recovery on chloroplast-encoded protein synthesis; and, iv) the sensitivity of photosynthesis to photoinhibition in the presence or absence of the carotenoid zeaxanthin. We show that: i) despite different sensitivities to photoinhibition, photoinhibition in all three plants occurred at the reaction centre of PSII; ii) there was no correlation between the extent of photoinhibition and the degradation of the D1 protein; iii) the susceptibility to photoinhibition by blockage of chloroplas-tencoded protein synthesis was much less in shade plants than in plants acclimated to higher light; and iv) inhibition of zeaxanthin formation increased the sensitivity to photoinhibition in pea, but not in the shade plant Tradescantia. We suggest that there are mechanistic differences in photoinhibition of sun and shade plants. In sun plants, an active repair cycle of PSII replaces photoinhibited reaction centres with photochemically active ones, thereby conferring partial protection against photoinhibition. However, in shade plants, this repair cycle is less important for protection against photoinhibition; instead, photoinhibited PSII reaction centres may confer, as they accumulate, increased protection of the remaining connected, functional PSII centres by controlled, nonphotochemical dissipation of excess excitation energy. 相似文献