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4302. Role of alternative oxidase pathway in protection against drought-induced photoinhibition in pepper leaves
- Creator:
- Hu, W. H., Yan, X. H., He, Y., and Ye, X. L.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, photoinhibition, alternative oxidase pathway, Capsicum annuum L, chlorophyll fluorescence, drought, 2, and 581
- Language:
- Multiple languages
- Description:
- 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 in alleviating drought-induced photoinhibition in pepper (Capsicum annuum L.). Inhibition of AOX pathway decreased photosynthesis and increased thermal energy dissipation in plants under normal conditions. It indicated that AOX pathway could influence chloroplast energy metabolism. Drought reduced carbon assimilation. Photoinhibition was caused by excess of absorbed light energy in spite of the increase of thermal energy dissipation and cyclic electron flow around PSI (CEF-PSI). Upregulation of AOX pathway in leaves experiencing drought would play a critical role in protection against photoinhibition by optimization of carbon assimilation and PSII function, which would avoid over-reduction of photosynthetic electron transport chain. However, inhibition of AOX pathway could be compensated by increasing the thermal energy dissipation and CEF-PSI under drought stress, and the compensation of CEF-PSI was especially significant., W. H. Hu, X. H. Yan, Y. He, X. L. Ye., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4303. Role of calcium ion in protection against heat and high irradiance stress-induced oxidative damage to photosynthesis of wheat leaves
- Creator:
- Zhao, Hui-Jie and Tan, Ji-Fang
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- cross stress of heat and high irradiance, ethyleneglycol-di(2-aminoethylether)-tetraacetic acid, lanthanum (III) chloride, photosynthesis, and Triticum
- Language:
- Multiple languages
- Description:
- Cross stress of heat and high irradiance (HI) resulted in the accumulation of active oxygen species and photo-oxidative damage to photosynthetic apparatus of wheat leaves during grain development. Pre-treatment with calcium ion protected the photosynthetic system from oxidative damage by reducing O-2 production, inhibiting lipid peroxidation, and retarding electrolyte leakage from cell. Therefore, high Fv/Fm [maximal photochemical efficiency of photosystem 2 (PS2) while all PS2 reaction centres are open], Fm/F0 (another expression for the maximal photochemical efficiency of PS2), ΦPS2 (actual quantum yield of PS2 under actinic irradiation), qP (photochemical quenching coefficient), and PN (net photosynthetic rate) were maintained, and lower qNP (non-photochemical quenching coefficient) of the leaves was kept under heat and HI stress. EGTA (a chelant of calcium ion) and LaCl3 (a blocker of Ca2+ channel in cytoplasmic membrane) had the opposite effect. Thus Ca ion may help protect the photosynthetic system of wheat leaves from oxidative damage induced by the cross stress of heat and HI. and Hui-Jie Zhao, Ji-Fang Tan.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4304. Role of changing environmental parameters in leaf gas exchange of Arbutus unedo L. assessed by field and laboratory measurements
- Creator:
- Vitale, M. and Manes, F.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- climate change, CO2 concentration, Mediterranean-type ecosystems, mesophyll conductance, net photosynthetic rate, physiological adaptation to stresses, respiration rates, ribulose-1; 5-bisphosphate carboxylase, oxygenase, stomatal conductance, and transpiration rate
- Language:
- Multiple languages
- Description:
- In the frame of the foreseen climate global changes we analysed the physiological responses of Arbutus unedo L. to the variations of carbon dioxide concentration, leaf temperature, and irradiance by measurements of leaf gas exchange and leaf water potential performed both in field and in the laboratory. Stomatal conductance was not affected by increase of leaf temperature. The growth conditions of potted plants likely made stomata more sensitive to the variation of external parameters than naturally growing plants. The interaction between high CO2 concentration and temperature involved important down-regulation mechanisms in the metabolic pathway of the carbon fixation. From an ecological point of view, the ability of A. unedo to adapt to the field stress makes it highly competitive in the Mediterranean plant community. and M. Vitale, F. Manes.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4305. Role of cyanide-resistant respiration during light-induced attraction of predators to herbivore-infested leaves
- Creator:
- Feng, H. Q., Sun, K., Wei, Y., Wang, R. F., Jia, L. Y., Zhang, J. P., and Li, Y.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, cyanide-resistant respiration, herbivore attack, light, predatory mites, 2, and 581
- Language:
- Multiple languages
- Description:
- The present work showed that spider mite-infested leaves placed in the light were more attractive to predatory mites than the infested leaves placed in the dark; furthermore, an increase in the light intensity enhanced this attractiveness. However, the increase of the light intensity did not change the attractiveness of the uninfested leaves to predatory mites. The capacity of cyanide-resistant respiration and the photosynthetic rates of both the infested and uninfested leaves increased with increasing light intensities, whereas the photosystem (PS) II chlorophyll (Chl) fluorescence decreased. The increase of the capacity of cyanide-resistant respiration in the infested leaves was more dramatic than that in the uninfested leaves, whereas the values of photosynthetic rates and Chl fluorescence were lower in the infested leaves than those in the uninfested leaves. Treatment of the infested and uninfested leaves with 1 mM salicylhydroxamic acid (SHAM, an inhibitor of cyanide-resistant respiration) decreased photosynthetic rates and caused further reductions in PSII fluorescence, especially under a higher light intensity. In contrast, the effects of SHAM on PSII fluorescence parameters and photosynthetic rates of the infested leaves were more dramatic than on those of the uninfested leaves. The treatment with SHAM did not significantly change the attractiveness of the infested or uninfested leaves to the predatory mites under all of the light intensities tested. These results indicated that cyanide-resistant respiration was not directly associated with the light-induced attraction of predators to plants, but it could play a role in the protection of photosynthesis. Such role might become relatively more important when photosynthesis is impaired by herbivores infestation. and H. Q. Feng ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4306. Role of fructose-1,6-bisphosphatase, fructose phosphotransferase, and phosphofructokinase in saccharide metabolism of four C3 grassland species under elevated CO2
- Creator:
- Nádas, E., Balogh, Á. , Kiss, F., Szente, K., Nagy, Z., Martínez-Carrasco, R., and Tuba, Z.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- acclimation, CO2 assimilation, fructose-1,6-bisphosphatase, gluconeogenesis, glucose-6-phosphate dehydrogenase, glycolysis, oxidative pentose phosphate pathway, phosphofructokinase, pyrophosphate D-fructose-6-phosphate l-phosphotransferase, and starch
- Language:
- Multiple languages
- Description:
- We studied the effects of 15-months of elevated (700 µmol mol-1) CO2 concentration (EC) on the CO2 assimilation rate, saccharide content, and the activity of key enzymes in the regulation of saccharide metabolism (glycolysis and gluconeogenesis) of four C3 perennial temperate grassland species, the dicots Filipendula vulgaris and Salvia nemorosa and the monocots Festuca rupicola and Dactylis glomerata. The acclimation of photosynthesis to EC was downward in F. rupicola and D. glomerata whereas it was upward in F. vulgaris and S. nemorosa. At EC, F. rupicola and F. vulgaris leaves accumulated starch while soluble sugar contents were higher in F. vulgaris and D. glomerata. EC decreased pyrophosphate-D-fructose-6-phosphate l-phosphotransferase (PFP, EC 2.7.1.90) activity assayed with Fru-2,6-P2 in F. vulgaris and D. glomerata and increased it in F. rupicola and S. nemorosa. Growth in EC decreased phosphofructokinase (PFK, EC 2.7.1.11) activity in all four species, the decrease being smallest in S. nemorosa and greatest in F. rupicola. With Fru-2,6-P2 in the assay medium, EC increased the PFP/PFK ratio, except in F. vulgaris. Cytosolic fructose-1,6-bisphosphatase (Fru-1,6-P2ase, EC 3.1.3.11) was inhibited by EC, the effect being greatest in F. vulgaris and smallest in F. rupicola. Glucose-6-phosphate dehydrogenase (G6PDH EC 1.1.1.49) activity was decreased by growth EC in the four species. Activity ratios of Fru-1,6-P2ase to PFP and PFK suggest that EC may shift sugar metabolism towards glycolysis in the dicots. and E. Nádas ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4307. Role of irradiance in the chilling injury of young maize plants studied by chlorophyll fluorescence induction measurements
- Creator:
- Janda, T., Szalai, G., Kissimon, J., Páldi, E., Marton, C., and Szigeti, Z.
- Format:
- Type:
- model:internalpart and TEXT
- Language:
- Multiple languages
- Description:
- During cold treatment of Zea mays L. plants there was a decrease in the level of Fv/Fm and in the quantum yield of photosynthetic electron transport. The degree of damage depended on the ambient temperature and on the irradiance (I). The lower the temperature and the higher the 1, the more pronounced damage occurred. This suggests that photoinhibition has an important role in the cold damage to young maize. Although there was no damage in complete darkness even at low temperature, the repair processes needed a normal temperature.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4308. Role of light-harvesting complex 2 dissociation in protecting the photosystem 2 reaction centres against photodamage in soybean leaves and thylakoids
- Creator:
- Zhang, Hai-Bo and Xu, Da-Quan
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, D1 protein, 5'-p-fluorosulfonylbenzoyl adenosine, Glycine, protein phosphorylation, and PS2 reaction centre
- Language:
- Multiple languages
- Description:
- The protective role of light-harvesting complex 2 (LHC2) dissociation from photosystem 2 (PS2) complex was explored by the 5'-p-fluorosulfonylbenzoyl adenosine (FSBA, an inhibitor of protein kinase) treatment at saturating irradiance (SI) in soybean leaves and thylakoids. The dissociation of some LHC2s from PS2 complex occurred after SI treatment, but FSBA treatment inhibited the dissociation as demonstrated by analysis of sucrose density gradient centrifugation of thylakoid preparation and low-temperature (77 K) chlorophyll (Chl) fluorescence. A significant increase in F0 and decrease in Fv/Fm occurred after SI, and the two parameters could largely recover to the levels of dark-adapted leaves after subsequent 3 h in the dark, but they could not recover in the FSBA-treated leaves at SI. Neither the electron transport activity of PS2 nor the D1 protein amount in vivo had significant change after SI without FSBA, whereas FSBA treatment at SI could result in significant decreases in both the PS2 electron transport activity and the D1 protein amount. When thylakoids instead of leaves were used, the PS2 electron transport activity and the D1 protein amount declined more after SI with FSBA than without FSBA. The phosphorylation level of PS2 core proteins increased, while the phosphorylation level of LHC2 proteins was reduced after SI. Also, the phosphorylation of PS2 core proteins could be greatly inhibited by the FSBA treatment at SI. Hence in soybean leaf the LHC2 dissociation is an effective strategy protecting PS2 reaction centres against over-excitation and photodamage by reducing the amount of photons transferred to the centres under SI, and the phosphorylation of PS2 core proteins plays an important role in the dissociation. and Hai-Bo Zhang, Da-Quan Xu.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4309. Role of nitrate in photosynthetic electron transport of Chlorella vulgaris
- Creator:
- Osman, M. El-Anwar H. and El-Naggar, A. H.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, DCMU, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, oxygen evolution rate, and photosystem 1 and 2 activities
- Language:
- Multiple languages
- Description:
- Addition of nitrate to a suspension of NO3--depleted Chlorella vulgaris cells raised the O2-evolving capacity of the organism by 60%. The rate of O2-evolution under flash irradiation of the depleted cells was drastically reduced, which could be restored by addition of NO3-. The 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB)-insensitive O2-evolution, i.e., photosystem (PS) 2 activity of NO3--depleted cells, showed a 75% stimulation by addition of NO3-. PS1-mediated electron transport was also stimulated (50%) by addition of NO3-. Fluorescence yields of the NO3--depleted cells were significantly reduced. A normal fluorescence response was restored by the addition of NO3-. The fluorescence yield of the NO3--depleted and DCMU-treated-cells increased significantly after addition of NO3- ions, indicating a further reduction of the primary acceptor of PS2 (Q). In addition, the low temperature fluorescence emission spectra showed that energy transfer to PS2 and PS1 was much higher when nitrate was present. Hence nitrate accelerates the light-induced charge transfer from the intact O2-evolving system to the primary electron acceptor of PS2 and stimulates the PS1-mediated electron transport. and M. El-Anwar H. Osman, A. H. El-Naggar.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4310. Role of thermal dissipation in the photoprotection in cucumber plants after exposure to a chill stress
- Creator:
- Zhou, Y. H., Mao, W. H., Zhang, Y. Y., Huang, L. F., Hu, W. H., and Yu, J. Q.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- alternative elctron sink, chilling, Cucumis sativus, photosynthesis, and photosystem 2
- Language:
- Multiple languages
- Description:
- Experiments were carried out to investigate the changes in CO2 assimilation, photon allocation, and photosynthetic electron flux in leaves of cucumber (Cucumis sativus L.) plants after chilling stress. Chilling significantly decreased CO2 assimilation, the energy flux via linear electron transport (J PS2) and non-constitutive thermal dissipation (J NPQ) but increased fluorescence and constitutive thermal dissipation (J f,D) in chilling-sensitive genotype Jinyan No. 4. In contrast, chilling had little effects on J NPQ and J f,D although CO2 assimilation and J PS2 were inhibited in chilling-tolerant genotype Jinchun No. 3. In parallel with the reduction in J PS2, electron flux to oxygenation and carboxylation by ribulose-1,5-bisphosphate carboxylase/oxygenase all significantly decreased while electron flux to O2 significantly increased, especially in chilling-sensitive genotype. Thermal and fluorescence dissipation were the main energy dissipation pathways whilst water-water cycle was an important electron sink when photosynthetic carbon reduction was suppressed after chilling. Chilling sensitivity of the photosynthetic apparatus was related to the operation of different photoprotection mechanisms. and Z. H. Zhou ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public