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2. Characterization of ruthenium chloride supported hill reaction in beet spinach thylakoids

Creator:
Mishra, Sujata R. and Sabat, S.C.
Format:
print
Type:
model:internalpart and TEXT
Subject:
anthraquinonc sulfonate, potassium cyanide, photosystem 1, photophosphory lation, pH effects, non- cyclic electron flow, mercuric chloride, diuron, dibromothymoquinone, and ATPase
Language:
Multiple languages
Description:
The photosynthetic election transport activities in beet spinách thylakoids were studied using ruthenium chloride as an electron acceptor, Like potassium ferricyanide, RUCI3 supported the non-cyclic electron flow with net evolution of oxygen. The rate of oxygen evolution was at its maximum with 0.5 mM RUCI3 at pH of 8.0 and the election flow coupled to translocation of protons into the thylakoid vesicles. Ruthenium chloride-supported oxygen evolution was inhibited by specific photosynthetic electron tiansport inhibitors like diuron, dibromothymoquinone, potassium cyanide, and mercuric chloride Unlike ferricyanide, the RuCl3-supported oxygen evolution was totally inliibited by potassium cyanide and mercuric chloride at both pH 8.0 and 6.5. Since potassium cyanide and mercuric chloride mostly interrupt the electron flow at plastocyanin level, RUCI3 probably accepts electrons mostly from photosystem 1 or its near vicinity. Besides electron acceptance, RUCI3 suppresses the photophosphoiylation activity in a manner similar to energy transfer inhibitors.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Chlorophyll fluorescence and photosynthetic gas exchange responses to irradiance of Tree of Heaven (Ailanthus Altissima) in contrasting urban environments

Creator:
Hamerlynck, E. P.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
areal leaf mass, diurnal courses of photosynthetic characteristics, fluorescence induction, irradiance, leaf dimensions, photoprotection, photosystem 2, quantum yield, and stomatal conductance
Language:
Multiple languages
Description:
Sun-and shade-adapted plants of Ailanthus altissima utilized thermal-dissipative photoprotection (NPQ) across a range of photosynthetic photon flux densities (PPFD), with higher NPQ and lower maximum quantum yield of photosystem 2 photochemistry (Fv/Fm) in sun-adapted individuals, suggesting increased engagement of antennae-based quenching. Photosynthetic quantum requirements (Qreq; number of photons per CO2) were similar in sun and shade plants, but were low and comparable to forest understory species. Diurnal measurements showed that PPFDs in both habitats were consistently above photosynthetic compensation irradiance, and frequently exceeded saturating values. In addition, sun- and shade-adapted individuals possessed stomata that tracked short-term fluctuations in PPFD. Thus A. altissima may be unique in that it couples high, shade-plant like photosynthetic efficiency with high photosynthetic capacity in high-irradiance, while stomatal attributes that optimize water use efficiency are maintained in the shade. These features may contribute to success of A. altissima in establishing in disturbance-prone urban systems, and facilitate its spread into more PPFD-limited and competitive natural ecosystems.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Comparative effects of salt-stress and alkali-stress on the growth, photosynthesis, solute accumulation, and ion balance of barley plants

Creator:
Yang, C.-W., Xu, H.-H., Wang, L.-L., Liu, J., Shi, D.-C., and Wang, D.-L.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Hordeum, intercellular CO2 concentration, photosynthesis, relative growth rate, roots, shoot, solute accumulation, stomatal conductance, transpiration rate, and water content
Language:
Multiple languages
Description:
We compared the effects of salt-stresses (SS, 1: 1 molar ratio of NaCl to Na2SO4) and alkali-stresses (AS, 1: 1 molar ratio of NaHCO3 to Na2CO3) on the growth, photosynthesis, solute accumulation, and ion balance of barley seedlings, to elucidate the mechanism of AS (high-pH) damage to plants and the physiological adaptive mechanism of plants to AS. The effects of SS on the water content, root system activity, membrane permeability, and the content of photosynthetic pigments were much less than those of AS. However, AS damaged root function, photosynthetic pigments, and the membrane system, led to the severe reductions in water content, root system activity, content of photosynthetic pigments, and net photosynthetic rate, and a sharp increase in electrolyte leakage rate. Moreover, with salinity higher than 60 mM, Na+ content increased slowly under SS and sharply under AS. This indicates that high-pH caused by AS might interfere with control of Na+ uptake in roots and increase intracellular Na+ to a toxic level, which may be the main cause of some damage emerging under higher AS. Under SS, barley accumulated organic acids, Cl-, SO4 2-, and NO3 - to balance the massive influx of cations, the contribution of inorganic ions to ion balance was greater than that of organic acids. However, AS might inhibit absorptions of NO3 - and Cl-, enhance organic acid synthesis, and SO4 2- absorption to maintain intracellular ion balance and stable pH. and C.-W. Wang ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

5. Effect of hypoxia and post-hypoxia on the fluctuations in contents of malate and citrate, the activity of malic enzyme, and on the intensity of gas exchange in moss gametophores

Creator:
Rut, G., Rzepka, A., and Krupa, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, calcium, malate, Mnium, photosynthesis, Polytrichum, post-hypoxia, and respiration
Language:
Multiple languages
Description:
Mosses are plants of simple anatomical structure and as they occur in habitats characterised not only by major changes in the concentrations of carbon dioxide, they suffer the stress of periodic water shortages or submergence in water. The condition of hypoxia (submergence in water or CaCl2 solution) prompted the increase in daily fluctuations in malate content, particularly in the gametophores of Polytrichum piliferum Hedw. No significant increases in daily fluctuations of citrate were found in the hypoxia and post-hypoxia conditions. Placing gametophores for 168 h in air with a concentration of CO2 at ∼ 350 μmol mol-1, and 21% of oxygen, after being submerged for 24 h in water, reduced the daily fluctuations of malate and citrate. Keeping the plants in these conditions for a long time (120-168 h) produced the increase in photosynthesis intensity in the gametophores of Mnium undulatum Hedw. and P. piliferum by 13% and 51%, respectively, when compared with plants submerged for 24 h. The intensity of respiration during post-hypoxia, however, was markedly lower compared with the intensity of the process recorded in hypoxia, particularly in the gametophores of P. piliferum. The increased daily fluctuations of malate and NAD(P)H in the studied species under hypoxia could constitute an important element of adaptive strategy to these conditions. and G. Rut, A. Rzepka, J. Krupa.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public