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42. Expression of the large isoform of ribulose-1,5-bisphosphate carboxylase/oxygenase activase gene driven by rbcS promoter in Oryza sativa enhances the photosynthetic capacity
- Creator:
- Wu, H. R., Ding, Z. S., Li, L. B., Jing, Y. X., and Kuang, T. Y.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carboxylation efficiency, chlorophyll fluorescence, net photosynthetic rate, photosystem 2, and transgenic rice
- Language:
- Multiple languages
- Description:
- In order to investigate the effect of large isoform of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activase (RuBPCO-A) on photosynthesis, cDNA of the enzyme (rca) was transferred to rice cultivars (Oryza sativa f. japonica cv. Nipponbare) under the control of RuBPCO small subunit gene promoter (rbcS) via Agrobacterium tumefaciens-mediated transformation. Transgenic rice plants were identified by polymerase chain reaction (PCR) and Southern and Western blot analyses. Net photosynthetic rate (PN ) values of the T1 transgenic lines 34 (T34) and 40 (T40) were 45.26 and 46.32 % higher than that of the control plants, respectively. At the same time, their carboxylation efficiency and RuBPCO initial activity, quantum yield of electron transport in photosystem 2 (ΦPS2), and steady state photochemical fluorescence quenching (qP) increased. In addition, heading time of the transgenic rice was advanced. Thus increasing the amount of large isoform of RuBPCO-A in the transgenic rice might have a stimulatory effect on both photosynthesis and plant growth. and H. R. Wu ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
43. Factors limiting photosynthetic recovery in sweet pepper leaves after short-term chilling stress under low irradiance
- Creator:
- Li, X.-G., Wang, X.-M., Meng, Q.-W., and Zou, Q.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Capsicum, chilling, chlorophyll fluorescence, Mehler reaction, P700, photoinhibiton, photorespiration, and photosystem 2
- Language:
- Multiple languages
- Description:
- The effects of chilling treatment (4 °C) under low irradiance, LI (100 μmol m-2 s-1) and in the dark on subsequent recovery of photosynthesis in chilling-sensitive sweet pepper leaves were investigated by comparing the ratio of quantum yields of photosystem (PS) 2 and CO2 assimilation, ΦPS2/ΦCO2, measured in normal air (21 % O2, NA) and low O2-air (2% O2, LOA), and by analyzing chlorophyll (Chl) a fluorescence parameters. Chilling treatment in the dark had little effect on Fv/Fm and ΦPS2/ΦCO2, but it caused the decrease of net photosynthetic rate (PN) under saturating irradiance after 6-h chilling treatment, indicating that short-term chilling alone did not induce PS2 photoinhibition. Furthermore, photorespiration and Mehler reaction also did not obviously change during subsequent recovery after chilling stress in the dark. During chilling treatment under LI, there were obvious changes in Fv/Fm and ΦPS2/ΦCO2, determined in NA or LOA. Fv/Fm could recover fully in 4 h at 25 °C, and ΦPS2/ΦCO2 increased at the end of the treatment, as determined in both NA and LOA. During subsequent recovery, ΦPS2/ΦCO2 in LOA decreased faster than in NA. Thus the Mehler reaction might play an important role during chilling treatment under LI, and photorespiration was an important process during the subsequent recovery. The recovery of PN under saturating irradiance determined in NA and LOA took about 50 h, implying that there were some factors besides CO2 assimilation limiting the recovery of photosynthesis. From the progress of reduced P700 and the increase of the Mehler reaction during chilling under LI we propose that active oxygen species were the factors inducing PS1 photoinhibition, which prevented the recovery of photosynthesis in optimal conditions because of the slow recovery of the oxidizable P700. and X.-G. Li ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
44. Ferredoxin-quinone reductase benefits cyclic electron flow around photosystem 1 in tobacco leaves upon exposure to chilling stress under low irradiance
- Creator:
- Li, X.-G., Xu, P.-L., Zhao, J.-P., Meng, J.-J., and He, Q.-W.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, cyclic electron flow, ferrodoxin quinone reductase, Nicotiana, non-photochemical quenching, photosystem 2, and xanthophyll cycle
- Language:
- Multiple languages
- Description:
- 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. and X.-G. Li ... [et al.].
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
45. Force field development on pigments of photosystem 2 reaction centre
- Creator:
- Palenčár, P., Vácha, F., and Kutý, M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- chlorophyll, photosystem 2, and plastoquinone
- Language:
- Multiple languages
- Description:
- We developed new parameters for molecular dynamics (MD) simulations, namely partial atomic charges, equilibrium bond-lengths, angles, dihedrals, atom types, and force constants of chlorophyll a (Chl) and plastoquinone (PQ), and both reduced and neutral form of primary acceptor (PHO) molecule. These parameters are essential for MD simulations that can interpret various structure functional relationships during primary processes of charge separation and stabilization in photosystem 2 reaction centres. and P. Palenčár, F. Vácha, M. Kutý.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
46. Glutathione counteracts the inhibitory effect induced by cadmium on photosynthetic process in soybean
- Creator:
- El-Shintinawy, F.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- carotenoids, chlorophyll, ethylene, fluorescence, emission spectra, fresh and dry mass of roots and shoots, Glycine, leaf and root dimensions, lipid peroxidation, and photosystem 2
- Language:
- Multiple languages
- Description:
- In soybean seedlings, Cd2+ affected growth and inhibited photosynthesis. Both the length and fresh mass decreased more in roots than in shoots. Cd2+ stress caused an increase in ratio of chlorophyll (Chl) (a+b)/b by 1.3 fold and ratio of total xanthophylls/β-carotene by 3 fold compared to the control. A reduced activity of photosystem 2 by about 85 % measured in Cd2+-treated chloroplasts was associated with a dramatic quenching of fluorescence emission intensity, with a band shift of 4 nm. A major suppression of absorption was accompanied with shift in peaks in the visible region of the spectrum. In Cd2+-treated chloroplasts a selective decline in linolenic acid (18:3), the most unsaturated fatty acid of chloroplasts, paralleled with the ten fold enhancement in ethylene production. A three fold increase in peroxidase activity was found in chloroplasts treated with Cd2+ compared to the control . Addition of 1 mM glutathione (GSH) counteracted all the retardation effects in soybean seedling growth induced by Cd2+. Thus GSH may control the Cd2+ growth inhibition as it detoxifies Cd2+ by reducing its concentration in the cytoplasm and removing hydrogen peroxide generated in chloroplasts.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
47. Greening of peas: parallel measurements of 77 K emission spectra, OJIP chlorophyll a fluorescence transient, period four oscillation of the initial fluorescence level, delayed light emission, and P700
- Creator:
- Srivastava, A., Strasser, R. J., and Govindjee
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- intermittent irradiation, photosystem 2, and Pisum sativum
- Language:
- Multiple languages
- Description:
- Irradiation of etiolated leaves leads to their greening. Although this problem has a long history, the question of whether the intermittent irradiation (IMI) grown plants have fully functional reaction centres as well as the oxygen clock, before exposure to continuous irradiation (CI), had not been resolved. To answer this question, as well as to analyze the development of the two photosystems, the following parallel measurements were made: (1) Emission spectra at 77 K; (2) OJIP chlorophyll (Chl) a fluorescence transient; (3) period 4 oscillation in the flash number dependence of initial fluorescence F0 (at 50 µs) and FJ (at 2 ms); and (4) P700. In the 1-ms-flash (FL) grown pea, that has a different biogenesis of the photosynthetic apparatus, delayed light emission (DLE) and Chl a fluorescence transient were measured in parallel. Quantitative analysis of Chl a fluorescence values provided the following conclusions: (1) IMI, not FL, plants have almost fully developed reaction centres and the oxygen clock. (2) Further greening of IMI plants under CI involves two phases: (a) during 3-4 h of CI, the number of PS2 units and connectivity between them increase, and then (b) light-harvesting antenna increases. (3) In FL, 10 min CI activates fully the oxygen clock. and A. Srivastava, R. J. Strasser, Govindjee.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
48. 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
49. Influence of heat shock on chlorophyll fluorescence of white oak (Quercus pubescens Willd.) leaves
- Creator:
- Dascaliuc, A., Ralea, T., and Cuza, P.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- photosystem 2 and temperature
- Language:
- Multiple languages
- Description:
- Chlorophyll fluorescence parameters of Quercus pubescens Willd. as response to heat shock (HS) by immersing leaves for 5 and 15 min in water of temperatures between 38 and 59 °C were examined. Fluorescence was measured after different periods of recovery (15, 30, 90, 210, and 1 440 min at 24/26 °C night/day temperature and 100 % humidity). The effective quantum yield of photosystem 2 (Y) in control and HS-treated leaves was always measured after previous 15 min irradiation. Under a 5 min HS, Y did not change after using temperatures below 44 °C, was rapidly restored after HS of moderate temperatures (44-48 °C), and progressively decreased and recovered eventually to the initial value after HS of high temperatures (48-52 °C). Y did not recover after HS with temperatures higher than 52 °C. Increase in the duration of HS from 5 to 15 min lead to change of the initial Y at each HS temperature, but the recovery processes were similar to those characteristic after 5 min incubation. The processes of recovery may depend mainly on the specificity of injuries caused by different heat shock temperatures. Thus Q. pubescens is able to preserve and recover the functional potential of its photosynthetic apparatus in response to HS up to 52 °C. and A. Dascaliuc, T. Ralea, P. Cuza.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
50. Influence of insect-infested cotyledons on early seedling growth of Mongolian oak, Quercus mongolica
- Creator:
- Yi, X. F. and Zhang, Z. B.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Curculio, dry mass, leaf, leaf area, net photosynthetic rate, nitrogen content, photochemical efficiency, photosystem 2, plant height, root, and weevil
- Language:
- Multiple languages
- Description:
- Insect-infested (II) acorns germinated 3 d earlier than the healthy (H) ones. However, germination ratio of II-acorns was strongly decreased compared with H-acorns and there were great differences in activities of amylase. We found an apparently lower net photosynthetic rate and total chlorophyll contents of the first true leaf of II-acorns than of the H-ones. Maximal photochemical efficiency of photosystem 2 (PS2, Fv/Fm) decreased in seedlings germinated from II-acorns than from the H-ones. Infestation of insects, especially for weevil (Curculio spp.) had significantly negative effects on length of taproots, height of plants, dry mass (DM) of roots and the first fully expanded true leaf. Leaf area and total N content of the first true leaf declined due to limitation of resource reserves in cotyledons. Damage of cotyledons caused by weevil accounted much for poor development of seedlings germinated from II-acorns. A mutual relationship between seedling establishment and seed-infesting insects may exist due to high predation on H-acorns by small rodents. and X. F. Yi, Z. B. Zhang
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public