Number of results to display per page
Search Results
12. Photoacclimation of Dunaliella tertiolecta (Chlorophyceae) under fluctuating irradiance
- Creator:
- Havelková-Doušová, H., Prášil, O., and Behrenfeld, M. J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- absorption and fluorescence excitation spectra, carotenoids, chlorophylls, diurnal course, fluorescence induction, growth rate, photosystem 2 antenna size, phytoplankton, vertical mixing, and xanthophyll cycle pigment
- Language:
- Multiple languages
- Description:
- We investigated photoacclimation of Dunaliella tertiolecta (Butcher) in irradiance (I) regimes simulating mixed layer conditions of turbid estuarine waters or lakes. D. tertiolecta was exposed to a range of fixed I regimes to establish baseline physiology-I relationships that were compared with subsequent photoacclimation to a simulated mixed layer. Measured indices of photoacclimation included cellular pigmentation, chlorophyll variable fluorescence, and effective photosystem 2 antenna size. While D. tertiolecta grown under fluctuating I maintained division rates comparable to cells grown at high I, the cells exhibited characteristics of photoacclimation consistent with cells grown under a stable regimes at irradiances considerably lower than the average I of the simulated mixed layer. and H. Havelková-Doušová, O. Prášil, M. J. Behrenfeld.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
13. Photoinhibition in chilling stressed Leguminosae: comparison of Vicia faba and Pisum sativum
- Creator:
- Lidon, F. C., Ribeiro, G., Santana, H., Marques, H., Correia, K., and Gouveia, S.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophylls, cytochromes, lipids, photoinhibition, photosystem 2, proteins, quinones, water oxidising complex, and xanthophyll cycle
- Language:
- Multiple languages
- Description:
- The concentrations of photosynthetic pigments decreased in both chilling stressed species but the ratios of chlorophyll (Chl) a/b and total carotenoids (Car)/Chls were depressed only in faba bean. The contents of α+β carotene and lutein+lutein-5,6-epoxide remained unaffected in both species, but the de-epoxidation state involving the components of xanthophyll cycle increased in pea. Under chilling stress the photosynthetic electron transport associated with photosystem 2, PS2 (with and without the water oxidising complex) decreased in both plant species, the inhibition being higher in faba bean. The intrachloroplast quinone pool also decreased in both stressed species, yet an opposite trend was found for cytochrome b559LP. Under stress an increasing peroxidation of thylakoid acyl lipids was detected in pea, but higher protein/Chl ratio was detected in faba bean. Thus the acceptor side of PS2 is mostly affected in both chilling stressed species, but faba bean is more sensitive. and F. C. Lidon ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
14. Photon-harvesting efficiency and arbuscular mycorrhiza in amphibious plants
- Creator:
- Šraj-Kržič, N., Pongrac, P., Regvar, M., and Gaberščik, A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- aerenchyma, anthocyanins, carotenoids, chlorophylls, intermittent aquatic habitats, photochemical efficiency, photosystem 2, species differences, and symbiosis
- Language:
- Multiple languages
- Description:
- The amphibious plant species of intermittent aquatic habitats thrive both submerged and emerged. In order to outline the adaptive characters of these two life forms photochemical efficiency of photosystem 2, leaf contents of chlorophyll (Chl) a and b, carotenoids (Car), anthocyanins (Ant), and UV-B absorbing compounds (UV-B abs), and root aerenchyma and arbuscular mycorrhizal (AM) colonisation were studied in Glyceria fluitans, Gratiola officinalis, Ranunculus lingua, Teucrium scordium, Sium latifolium, Sparganium emersum, and Veronica anagallis-aquatica. Water level fluctuations did not exert a severe effect on photon harvesting efficiency. Submerged specimens had higher contents of Car and Ant whereas higher contents of UV-B abs were found in emerged specimens indicating efficient protection against the harmful effects of solar radiation. Roots of all species studied had extensive aerenchyma and were colonised by AM fungi, which were significantly more abundant in emerged specimens. This is the first report on AM symbiosis in S. latifolium and S. emersum. and N. Šraj-Kržič ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
15. Photosynthesis and photosystem 2 efficiency of two salt-adapted halophytic seashore Cakile maritima ecotypes
- Creator:
- Megdiche, W., Hessini, K., Gharbi, F., Jaleel, C. A., Ksouri, R., and Abdelly, C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophylls, fluorescence, intracellular CO2 concentration, quenching, relative growth rate, salt tolerance, stomatal conductance, iranspiration rate, and water use efficiency
- Language:
- Multiple languages
- Description:
- The effects of salinity (0-400 mM NaCl, marked S0, S100, S200, and S400) on growth, photosynthesis, photosystem 2 (PS2) efficiency, ion relations, and pigment contents were studied in two seashore Cakile maritima ecotypes (Tabarka and Jerba, respectively, sampled from humid and arid bioclimatic areas). Growth of Jerba plants was improved at S100 as compared to S0. Tabarka growth was inhibited by salinity at all NaCl concentrations. Leaf sodium and chloride concentrations increased with medium salinity and were higher in Jerba than in Tabarka plants. Chlorophyll content, net photosynthetic rate, stomatal conductance (gs), and intracellular CO2 concentration were stimulated at moderate salinity (S100) in Jerba plants and inhibited at higher salt concentrations in both ecotypes: gs was the most reduced parameter. The maximum quantum efficiency of PS2 (Fv/Fm), quantum yield, linear electron transport rate, and efficiency of excitation energy capture by open PS2 reaction centres showed no significant changes with increasing salt concentration in Jerba plant and were decreased in Tabarka subjected to S400. However, the efficiency of dissipation of excess photon energy in the PS2 antenna was maintained in Jerba and was increased in Tabarka plants challenged with S400. Hence the relative salt tolerance of Jerba was associated with a better ability to use Na+ and Cl- for osmotic adjustment, the absence of pigment degradation, and the concomitant PS2 protection from photodamage. and W. Megdiche ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
16. Photosynthesis parameters in two cultivars of mulberry differing in salt tolerance
- Creator:
- Giridara Kumar, S., Lakshmi, A., Madhusudhan, K. V., Ramanjulu, S., and Sudhakar, C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophylls, intercellular CO2 concentration, leaf area, leaf dry mass, Morus alba, net photosynthetic rate, salt stress, stomatal conductance, transpiration, and water use efficiency
- Language:
- Multiple languages
- Description:
- Three-month-old mulberry (Morus alba L.) cultivars (salt tolerant cv. S1 and salt sensitive cv. ATP) were subjected to different concentrations of NaCl for 12 d. Leaf area, dry mass accumulation, total chlorophyll (Chl) content, net CO2 assimilation rate (PN), stomatal conductance (gs), and transpiration rate (E) declined, and intercellular CO2 concentration (Ci) increased. The changes in these parameters were dependent on stress severity and duration, and differed between the two cultivars. The tolerant cultivar showed a lesser reduction in PN and gs coupled with a better Ci and water use efficiency (WUE) than the sensitive cultivar. and S. Giridara Kumar ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
17. Photosynthetic parameters of maize (Zea mays L.) inbred lines and F1 hybrids: Their different response to, and recovery from rapid or gradual onset of low-temperature stress
- Creator:
- Holá, D., Langrová, K., Kočová, M., and Rothová, O.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophylls, genotypes, Hill reaction, intra-specific variability, and photosystem 1 and photosystem 2
- Language:
- Multiple languages
- Description:
- The activity of photosystems (PS) 1 and 2, together with the content and ratio of photosynthetic pigments, were measured in three inbred lines and two F1 hybrids of maize (Zea mays L.), grown in either optimum or low temperature (LT) conditions. The ability of chilling-stressed plants to deal with the negative effects of long-term exposure to LT and to recover the efficiency of photosynthetic apparatus after their return to optimum temperatures was examined during spring and autumn seasons. The aim was to analyse the possible differences between the rapid and gradual onset of LT on the response of young maize plants to chilling stress. The distinctive superiority of hybrids over their parental lines, found during the exposure of maize plants to LT, was not always retained after the return of chilling-stressed plants to optimum growth conditions. The response of individual genotypes to chilling stress, as well as their ability to recover the photosynthetic efficiency from the cold-induced damage, strongly depended also on the duration and the rapidity of the onset of LT. and D. Holá ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
18. The effect of in vitro culture conditions on the pattern of photoinhibition during acclimation of gardenia plantlets to ex vitro conditions
- Creator:
- Serret, M. D., Trillas, M. I., and Araus, J. L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophylls, CO2, fluorescence induction, Gardenia jasminoides, irradiance, micropropagation, photosynthetic pigments, and sacharose
- Language:
- Multiple languages
- Description:
- We tested the effect of growing conditions during micropropagation on the fast kinetics of chlorophyll (Chl) fluorescence of Gardenia jasminoides Ellis plantlets during a 4-week acclimation to ex vitro. We studied whether photoautotrophic growing in vitro produced plantlets with less photoinhibition impairment during acclimation. Of the growing conditions stimulating photoautotrophy in vitro, only loose tube caps had a positive effect, whereas low sucrose or sucrose-free content in the medium and high PPFD showed a negative effect. Thus, plantlets cultured with 3 % (m/v) of sucrose were subsequently less photoinhibited throughout acclimation than those cultured with low sucrose (0.5 %) or sucrose-free media. Moreover, at the end of acclimation the former plantlets showed Fv/Fm and Fv/F0 ratios typical of unstressed ex vitro plants as well as a higher Chl content and ratio of Chls to carotenoids. Plantlets cultured at a photosynthetic photon fluence density (PPFD) of 50 µmol m-2 s-1 also showed a better performance at the end of acclimation than those cultured at a higher (110 µmol m-2 s-1) PPFD. Thus except in the case of loose-tube closure, gardenia plantlets cultured in vitro under conventional sucrose concentration and PPFD are the least photoinhibited during acclimation. Nevertheless, significant interactions between the in vitro growing factors were observed at the end of acclimation. and M. D. Serret, M. I. Trillas, J. L. Araus.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
19. The effect of low growth temperature on Hill reaction and photosystem 1 activities and pigment contents in maize inbred lines and their F1 hybrids
- Creator:
- Körnerová, M. and Holá, D.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophylls, genetic analysis, heterosis, intraspecific variation, photosystem 2, and Zea mays
- Language:
- Multiple languages
- Description:
- Young plants of maize inbred lines CE777, CE704, and CE810 and their F1 hybrids displaying a positive heterotic effect in various photosynthetic characteristics were exposed to low temperature during their early growth developmental stage. The photochemical activity of isolated mesophyll chloroplasts and the contents of photosynthetic pigments in leaves of stressed and non-stressed plants were compared with the aim to find out the possible changes in the relationship between parents and hybrids, and to determine the genetic basis of heterosis in F1 generation. Strong decrease in the content of chlorophylls was observed for all genotypes examined when plants were subjected to low growth temperature. Similar change was recorded for Hill reaction activity (HRA) of inbred lines but not of their F1 hybrids, and no significant response at all was found for photosystem 1 (PS1) activity or the total carotenoids content. The intraspecific variation due to differences between genotypes was found for most of photosynthetic characteristics examined. This variation was caused by the additive and dominance genetic effects. Positive dominance was the main cause of positive heterosis in HRA and in the contents of photosynthetic pigments and was much more pronounced in the stressed plants compared to the non-stressed ones. The maternal additive effects participated in the inheritance of contents of photosynthetic pigments in plants exposed to low temperature, too. and M. Körnerová, D. Holá.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
20. The ultrastructure of chloroplasts, content of photosynthetic pigments, and photochemical activity of maize (Zea mays L.) as influenced by different concentrations of the herbicide amitrole
- Creator:
- Pechová, R., Kutík, J., Holá, D., Kočová, M., Haisel, D., and Vičánková, A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- 3-amino-1,2,4-triazole, carotenoids, chlorophylls, Hill reaction, and photosystems 1 and 2
- Language:
- Multiple languages
- Description:
- The effect of three different concentrations of amitrole (AM), a bleaching herbicide affecting carotenogenesis, on chloroplast ultrastructure, photosynthetic pigment contents, and photochemical activity was studied in two maize genotypes differing in photosynthetic characteristics. The content of photosynthetic pigments in leaves of plants treated with low (20 μM) AM concentration was similar to control plants and no damaging effect of the herbicide on the ultrastructure of either mesophyll (MC) or bundle-sheath (BSC) cell chloroplasts was observed. Higher (60 and 120 μM) concentrations of AM caused a significant decrease in the content of carotenoids (especially xanthophylls), which was followed by photooxidative destruction of chlorophylls and some alterations of chloroplast ultrastructure. MC chloroplasts appeared more sensitive to the damaging effect of AM compared to BSC chloroplasts. A significant decrease in the amount of both granal and intergranal thylakoids in MC chloroplasts was observed with the increasing concentration of AM. As regards BSC chloroplasts, rapid decrease in the volume density of starch inclusions was found in plants treated with higher concentrations of AM. When 120 μM AM was used, both MC and BSC chloroplasts contained just a few thylakoid membranes that were strongly altered. The changes in the ultrastructure of MC chloroplasts were accompanied by the changes in their photochemical activity. The formation of chloroplast protrusions after treatment of plants with AM as well as in control plants was also observed. and R. Pechová ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
- « Previous
- Next »
- 1
- 2
- 3