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2732. Hickey, M., King, C.: The Cambridge illustrated glossary of botanical terms
- Creator:
- Blažek, M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanical terminology
- Language:
- Multiple languages
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2733. High contents of anthocyanins in young leaves are correlated with low pools of xanthophyll cycle components and low risk of photoinhibition
- Creator:
- Manetas, Y., Drinia, A., and Petropoulou, Y.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophylls, fluorescence kinetics, leaf age, Ricinus communis, and Rosa sp.
- Language:
- Multiple languages
- Description:
- We checked the hypothesis that the transient presence of anthocyanins in young leaves serves a photoprotective function. For this purpose, Rosa sp. and Ricinus communis L., whose young leaves are red to become green upon maturation, were used. Thus, young leaves with high and mature leaves with low anthocyanin contents were analysed concerning their carotenoid (Car) composition and susceptibility to photoinhibition. Cars, including the components of the xanthophyll cycle, had similar contents in young and mature leaves, when expressed on a chlorophyll basis. Yet, when expressed on a leaf area basis or on the assumed photon absorptive capacity of leaves, Cars contents were considerably lower in anthocyanic young leaves. Although this may indicate a low photodissipative potential, red young leaves were considerably less susceptible to photoinhibitory damage. The results are compatible with a photoprotective function of anthocyanins, indicating also that their presence may compensate for a low capacity in the xanthophyll cycle-dependent harmless dissipation of excess excitation energy. and Y. Manetas, A. Drinia, Y. Petropoulou.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2734. High irradiance effects on the xanthophyll cycle pigments and the activity of violaxanthin de-epoxidase in soybean callus
- Creator:
- Pandey, D. M., Kim, K. H., Kang, K. H., and Yeo, U. D.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- antheraxanthin, Glycine max, HPLC, neoxanthin, violaxanthin, and zeaxanthin
- Language:
- Multiple languages
- Description:
- High irradiance (HI) effects on xanthophyll cycle pigments (XCP) and activity of violaxanthin de-epoxidase (VDE) in terms of de-epoxidation index (DEI) were studied in soybean calli. The calli from the hypocotyl segments of 5-d seedlings were induced on a solid (1.1 % agar) MS medium (pH 5.8) supplemented with 4.52 μM 2,4-dichloro-phenoxyacetic acid, 2.32 μM kinetin, and 3 % sucrose. After a 30 d cultivation, the green calli were irradiated for 24 h with "white light" (HI, 1 300 μmol m-2 s-1) and VDE was isolated from the photosystem 2 (PS2) particles. In the control (0 h irradiation) callus, the reaction of PS2 particles with VDE in the presence or absence of Tween 20 resulted in the decrease of VIO content and the increase of ZEA content. In the 24 h HI-callus, the reaction of PS2 particles in the absence of VDE led to the decrease of VIO and ANT contents and increase of ZEA content. In the control, DEIs in the presence of VDE with or without 0.1 %Tween 20 (1.04 and 1.06, respectively) were significantly higher than the DEI (0.76) in the absence of VDE. In the HI-callus, DEIs in the presence of VDE with or without 0.1 %Tween 20 (0.98 and 0.96, respectively) were similar to that (1.03) in the absence of VDE. and D. M. Pandey ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2735. High irradiance induced changes of photosystem 2 in young and mature needles of cypress (Cupressus sempervirens L.)
- Creator:
- La Porta, N., Bertamini, M., Nedunchezhian, N., and Muthuchelian, K.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- acclimation to irradiance, chlorophyll fluorescence, D1 protein, donor side, electron transport, photoinhibition, photosystem 2, and proteins
- Language:
- Multiple languages
- Description:
- Photoinhibition of photosynthesis was studied in young and mature detached sun needles of cypress under high irradiance (HI) of about 1 900 μmol m-2 s-1. The degree of photoinhibition was determined by means of the ratio of variable to maximum chlorophyll (Chl) fluorescence (Fv/Fm) and electron transport measurements. Compared with the mature needles, the young needles, containing about half the amount of Chl a+b per unit area, exhibited a higher proportion of total carotenoids (Car) as xanthophyll cycle pigments and had an increased ratio of Car/Chl a+b. The potential efficiency of photosystem (PS) 2, Fv/Fm, markedly declined in HI-treated young needles without significant increase of F0 level. In contrast, the Fv/Fm ratio declined with significant increase of F0 level in mature needles. In isolated thylakoids, the rate of whole chain and PS2 activity markedly decreased in young HI-needles in comparison with mature needles. A smaller inhibition of PS1 activity was observed in both needles. In the subsequent dark incubation, fast recovery was found in both needle Types that reached maximum PS2 efficiencies similar to those observed in non-photoinhibited needles. The artificial exogenous electron donors DPC, NH2OH, and Mn2+ failed to restore the HI-induced loss of PS2 activity in mature needles, while DPC and NH2OH significantly restored it in young needles. Hence, HI-inactivation was on the donor side of PS2 in young needles and on the acceptor side of PS2 in mature needles. Quantification of the PS2 reaction centre proteins D1 and 33 kDa protein of water splitting complex following HI-exposure of needles showed pronounced differences between young and mature needles. The large loss of PS2 activity in HI-needles was due to the marked loss of D1 protein of the PS2 reaction centre in mature needles and of the 33 kDa protein in young needles. and N. La Porta ... [et al.]
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2736. High photosynthetic efficiency of a rice (Oryza sativa L.) xantha mutant
- Creator:
- Zhou, Xiang-sheng, Wu, Dian-xing, Shen, Sheng-quan, Sun, Jun-wei, and Shu, Qing-yao
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll b-deficiency, chlorophyll fluorescence, net photosynthetic rate, Oryza sativa, photosynthetic efficiency, and xantha mutation
- Language:
- Multiple languages
- Description:
- Comparative analysis revealed that a xantha rice mutant (cv. Huangyu B) had higher ratios of chlorophyll (Chl) a/b and carotenoids/Chl, and higher photosynthetic efficiency than its wild type parent (cv. II32 B). Unexpectedly, the mutant had higher net photosynthetic rate (PN) than II32 B. This might have resulted from its lower non-photochemical quenching (qN) but higher maximal photochemical efficiency (FV/FM), higher excitation energy capture efficiency of photosystem 2 (PS2) reaction centres (FV'/FM'), higher photochemical quenching (qP), higher effective PS2 quantum yield (ΦPS2), and higher non-cyclic electron transport rate (ETR). This is the first report of a chlorophyll mutant that has higher photosynthetic efficiency and main Chl fluorescence parameters than its wild type. This mutant could become a unique material both for the basic research on photosynthesis and for the development of high yielding rice cultivars. and X.-S. Zhou ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2737. High temperature induced alterations in energy transfer in phycobilisomes of the cyanobacterium Spirulina platensis
- Creator:
- Murthy, S. D. S., Ramanaiah, V. V., and Sudhir, P.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- absorption spectra and fluorescence emisson spectra at room and low temperature
- Language:
- Multiple languages
- Description:
- Exposure of intact cells of Spirulina to high temperature (HT) stress (40-60 °C) caused decrease in absorption spectrum and fluorescence emission spectrum. Low temperature emission spectra were altered at phycocyanin (PC) level. Room and low temperature emission spectra of intact phycobilisomes showed that PC was the main target in this cyanobacterium for the altered energy transfer under HT. and S .D. S. Murthy, V. V. Ramanaiah, P. Sudhir.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2738. High-irradiance stress and photochemical activities of photosystems 1 and 2 in vivo
- Creator:
- Veeranjaneyulu, K., Charland, M., and Leblanc, R. M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Acer saccharum, light-harvesting complex 2, and photoacoustic spectroscopy
- Language:
- Multiple languages
- Description:
- High-irradiance (HI) stress induced changes in the photosynthetic energy storage (ES) of photosystems 1 (ESPS1) and 2 (ESPS2) were studied with 650 nm modulated radiation in intact sugar maple (Acer saccharum Marsh.) leaves. HI-treatment (420 W m-2, 1 h) caused an inhibition of about 40 % in ESPS2 and an enhancement of about 60 % in ESPS1. The rate of PS1 cyclic electron transport, measured with 705 nm modulated radiation, also increased in HI-treated leaves. There was a clear state 1- state 2 transition in HI-treated leaves. ESPS1 increased significantly and ESPS2 decreased drastically in leaves preadapted to state 1 after HI (600 W m-2, 30 min) treatment. Thus, the increase in PS1 activity observed immediately after HI-treatment in leaves preadapted to state 1 can be due to the coupling of LHC2 to PS1 during the HI-treatment. Further, the dissociation of LHC2 from PS2 during the HI-treatment resulted in apparently (about 15 %) greater inhibition than the "true" inhibition of PS2 activity. The presence of LHC2 with PS2 (state 1) at the time of HI-treatment caused no additional damage to PS2 or its coupling to PS1 offered no apparent HI-treatment. Further, the dissociation of LHC2 from PS2 during the HI-treatment resulted in apparently (about 15 %) greater inhibition than the "true" inhibition of PS2 activity. The presence of LHC2 with PS2 (state 1) at the time of HI-treatment caused no additional damage to PS2 or its coupling to PS1 offered no apparent protection to the photosynthetic apparatus. and K. Veeranjaneyulu, M. Charland, R. M. Leblanc.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2739. High-light-induced superoxide anion radical formation in cytochrome b6f complex from spinach as detected by EPR spectroscopy
- Creator:
- Sang, M., Qin, X.-C., Wang, W.-D., Xie, J., Chen, X.-B., Wang, K. B., Zhang, J.-P., Li, L.-B., and Kuang, T. Y.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, Cyt b6f, EPR, photoprotection, and superoxide anion radical
- Language:
- Multiple languages
- Description:
- The generation of superoxide anion radical (O2.-) in the cytochrome b6f complex (Cyt b6f) of spinach under high-light illumination was studied using electron paramagnetic resonance spectroscopy. The generation of O2.- was lost in the absence of molecular oxygen. It was also suppressed in the presence of NaN3 and could be scavenged by extraneous antioxidants such as ascorbate, β-carotene, and glutathione. The results also indicate that O2.-, which is produced under high-light illumination of the Cyt b6f from spinach, might be generated from a reaction involing 1O2, and the Rieske Fe-S protein could serve as the electron donor in the O2.- production. The mechanism of photoprotection of the Cyt b6f complex by antioxidants is discussed. and M. Sang ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
2740. High-light-like photosynthetic responses of Cucumis sativus leaves acclimated to fluorescent illumination with a high red:far-red ratio: interaction between light quality and quantity
- Creator:
- Shibuya, T., Endo, R., Hayashi, N., and Kitaya, Y.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- botanika, botany, fluorescent lamp, gross photosynthetic rate, leaf mass per unit area, light quality, quantum efficiency of photosystem II, 2, and 58
- Language:
- Multiple languages
- Description:
- This study evaluated the photosynthetic responses of Cucumis sativus leaves acclimated to illumination from three-band white fluorescent lamps with a high red:far-red (R:FR) ratio (R:FR = 10.5) and the photosynthetic responses of leaves acclimated to metal-halide lamps that provided a spectrum similar to that of natural light (R:FR = 1.2) at acclimation photosynthetic photon flux density (PPFD) of 100 to 700 μmol m-2 s-1. The maximum gross photosynthetic rate (PG) of the fluorescent-acclimated leaves was approximately 1.4 times that of the metal-halide-acclimated leaves at all acclimation PPFDs. The ratio of quantum efficiency of photosystem II (ΦPSII) of the fluorescent-acclimated leaves to that of the metal-halide-acclimated leaves tended to increase with increasing acclimation PPFD, whereas the corresponding ratios for the leaf mass per unit area tended to decrease with increasing acclimation PPFD. These results suggest that the greater maximum PG of the fluorescent-acclimated leaves resulted from an interaction between the acclimation light quality and quantity, which was mainly caused by the greater leaf biomass for photosynthesis per area at low acclimation PPFDs and by the higher ΦPSII as a result of changes in characteristics and distribution of chloroplasts, or a combination of these factors at high acclimation PPFDs., T. Shibuya .... [et al.]., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public