Introduction to Special Issue on Chlorophyll Fluorescence

Reto J. Strasser, Ladislav Nedbal

Photosynthetica 1999, 37(2):161 | DOI: 10.1023/A:1007043602479

Photochemical and Thermal Phases of Chlorophyll a Fluorescence

G. Samson, O. Prášil, B. Yaakoubd

Photosynthetica 1999, 37(2):163-182 | DOI: 10.1023/A:1007095619317

The measurement of variable chlorophyll (Chl) a fluorescence is widely used as a convenient and versatile tool in photosynthesis research. In many applications empirical correlations and simplified models of Chl a fluorescence are used with success. Nevertheless, variable Chl a fluorescence provides only indirect and complex image of processes occurring within photosynthetic membranes and such simplifications have only limited validity. In this review we elucidate some controversial and still unresolved questions about the origin and interpretation of the variable Chl a fluorescence induction and the proper use of variable...

Integrity and Activity of Photosystem 2 Complexes Isolated from the Thermophilic Cyanobacterium Synechococcus Elongatus Using Various Detergents

E. Šetlíková, D. Sofrová, O. Prášil, P. Budáč, M. Koblížek, I. Šetlík

Photosynthetica 1999, 37(2):183-200 | DOI: 10.1023/A:1007047703388

The efficiency in selective extraction of photosystem (PS) 2 oxygen evolving complexes was compared among seven detergents. These were applied to thylakoid membranes of the thermophilic cyanobacterium Synechococcus elongatus. Used were five non-ionic detergents with one ionic and one zwitterionic for comparison. To compare the suitability and efficiency of the detergents the following properties of the extracts were examined: maximum rate of oxygen evolution with various electron acceptors, the relative variable fluorescence (F_V/F_M), the contamination of the extract with photosystem (PS) 1, and the status of the electron...

Single-Turnover Flashes to Saturate the Q_A Reduction in a Leaf were Generated by the Light-Emitting Diodes from a Double Modulation Kinetic Chlorophyll Fluorometer

O. Urban, M. Trtilek, T. Feild, L. Nedbal

Photosynthetica 1999, 37(2):201-207 | DOI: 10.1023/A:1007099720226

The earlier developed double-modulation chlorphyll (Chl) fluorometer was modified for measurements with intact leaves of higher plants. The Chl fluorometer is based on a non-periodic modulation of both actinic and measuring flashes. In addition, continuous orange actinic and far-red radiation were produced by separate arrays of light-emitting diodes (LEDs). Programmable timing of the flashes allows to cover a wide dynamic range from microseconds to minutes. We have demonstrated that the LEDs can produce single-turnover flashes that saturate Q_A reduction of intact leaves of Glyceria maxima and shoots of Picea abies.

Sensitivity of the Algal Biotest ISO 10253 to the Photosystem 2 Herbicides in Seawater

J. Soukupová, A. Lukavská, J. Lukavský, L. Nedbal

Photosynthetica 1999, 37(2):209-216 | DOI: 10.1023/A:1007051804296

The sensitivity of marine algal biotest ISO 10253 to the photosystem 2 (PS2) herbicide diuron (DCMU) was determined. Using the diatom Phaeodactylum tricornutum, we found that the algal growth rate was reduced to 50 % of the control value (EC₅₀) for ca. 200 nM DCMU. This value is too high to allow a practical application of the biotest for concentrations of the PS2 herbicides found in natural waters. The mechanisms causing the low sensitivity of the biotest to the PS2 herbicide were investigated by measuring parameters of photosynthetic apparatus in the diatom prior and during the biotest. The apparent dissociation constant...

Photochemical and Non-Photochemical Quenching Coefficients of the Chlorophyll Fluorescence: Comparison of Variation and Limits

C. Buschmann

Photosynthetica 1999, 37(2):217-224 | DOI: 10.1023/A:1007003921135

There are several types of quenching coefficients currently in use which describe the decrease of the chlorophyll fluorescence: the photochemical quenching coefficients q_P and q_(P)rel and the non-photochemical quenching coefficients q_N, q_(N)rel, and NPQ. These five coefficients were calculated for a broad variety of cases of the fluorescence signals in a normal, realistic range and for determining the limits in a range with extremely low and high fluorescence values. The calculations showed that the quenching coefficients currently in use are not only numbers between 0 and 1 as one would expect when taking...

Excitation-Emission Map as a Tool in Studies of Photosynthetic Pigment-Protein Complexes

Mika Keränen, Eva-Mari Aro, Esa Tyystjärvi

Photosynthetica 1999, 37(2):225-237 | DOI: 10.1023/A:1007187105205

Excitation-emission maps were constructed by measuring emission spectra from tobacco thylakoids and from thylakoids and intact cells of the cyanobacterium Synechocystis 6803. The measurement of such maps is greatly facilitated by the current diode-array detector technology. We show that excitation-emission maps are valuable tools for studies of the structure and energy transfer pathways in photosynthetic systems.

Brooks, D.W.: Web-Teaching

Z. Šesták

Photosynthetica 1999, 37(2):238 | DOI: 10.1023/A:1007180610656

Remote Sensing of Canopy Photosynthetic Performances: Two Complementary Ways for Assessing the Photochemical Reflectance Index

M. Méthy, R. Joffre, S. Rambal

Photosynthetica 1999, 37(2):239-247 | DOI: 10.1023/A:1007143322043

Two methods have been developed concurrently for hyperspectral measurements of plant canopy reflectance in two narrow wavelength bands centred around 531 and 570 nm. A laboratory-built two-channel radiometer provided an easy and quick estimation of the Photochemical Reflectance Index PRI = (R₅₃₁ - R₅₇₀)/(R₅₇₀ + R₅₃₁) of a plot of alfalfa. A CCD digital camera provided multispectral imaging and the analysis of this index on the same target. The two devices are complementary. The results of measurements are complementary with those of chlorophyll fluorescence induction.

Briggs, D., Walters, S.M.: Plant Variation and Evolution

D. Holá

Photosynthetica 1999, 37(2):248 | DOI: 10.1023/A:1007128626586

Measurements of Phytoplankton of Sub-Nanomolar Chlorophyll Concentrations by a Modified Double-Modulation Fluorometer

N. Dijkman, D. Kaftan, M. Trtílek, L. Nedbal

Photosynthetica 1999, 37(2):249-254 | DOI: 10.1023/A:1007160106113

A modification of the double-modulation fluorometer is described that allows measuring very dilute phytoplankton samples. The high sensitivity is achieved by increasing the sample volume and by collecting the fluorescence from the large volume by an integrating sphere. The sensitivity of the instrument increased approximately proportionally to the volume of the sample. A further improvement of the sensitivity was achieved by replacing the PIN photodiode of the earlier versions by a photomultiplier. The instrument was used to measure fluorescence induction, F₀ and F_m parameters, and Q_A ^-reoxidation kinetics...

Decrease of Fluorescence Intensity After the K Step in Chlorophyll a Fluorescence Induction is Suppressed by Electron Acceptors and Donors to Photosystem 2

D. Lazár, P. Pospíšil, J. Nauš

Photosynthetica 1999, 37(2):255-265 | DOI: 10.1023/A:1007112222952

Chlorophyll a fluorescence induction measured by a fluorometer with a high temperature stressed plant material shows a new K step which is a clear peak due to fast fluorescence rise and subsequent decrease of fluorescence intensity. We focused on an explanation of the decrease of fluorescence after the K step using artificial electron acceptors and donors to photosystem 2 (PS2). Addition of the artificial electron acceptors or donors suppressed the decrease of fluorescence after the K step. We suggest that the decrease mainly reflects (by more than 81 %) an energy loss process in the reaction centre of PS2 which is most probably a nonradiative...

King, J.: Reaching for the Sun: How Plants Work

J. Čatský

Photosynthetica 1999, 37(2):266 | DOI: 10.1023/A:1007132727495

ΔpH-Dependent Fluorescence Quenching and Its Photoprotective Role in the Unicellular Red Alga Rhodella Violacea

M. Ritz, K.V. Neverov, A. L. Etienne

Photosynthetica 1999, 37(2):267-280 | DOI: 10.1023/A:1007164207022

Plants have developed various photoprotective mechanisms to resist irradiation stress. One of the photoprotective mechanisms described in the literature for LHC2-containing organisms involves a down-regulation of photosystem (PS) 2 occurring simultaneously with the build-up of a proton gradient across the thylakoid membrane (ΔpH). It is often correlated with deepoxidation of xanthophylls located in LHC2. In Rhodophyta instead of LHC2, the peripheral antenna of PS2 consists of a large extramembrane complex, the phycobilisome (PBS), which transfers its excitation to the core antennae of PS2 composed of the CP43 and CP47 protein-chlorophyll...

A Long-Term Response of Chlorophyll Fluorescence Induction to One-Shot Application of Cyanazine on Barley Plants and Its Relation to Crop Yield

M. Matoušková, J. Nauš, M. Flašarová

Photosynthetica 1999, 37(2):281-294 | DOI: 10.1023/A:1007116323860

Field-grown plants of spring barley (Hordeum vulgare L. cv. Akcent) in the growth phase 30 DC (beginning of stem extension) were exposed to a one-shot application of a commercial product containing cyanazine (Bladex 50 SC) in two doses, C₃₀ and C₆₀ (30 and 60 mg m^-2). The reaction of the plant photosynthetic system was followed non-destructively using chlorophyll fluorescence induction (the O-J-I-P transient) within three weeks after the application in the fifth developed leaf and three further gradually appearing leaves. An immediate response of plants to the application of cyanazine and a regeneration...

Gradual Disassembly of Photosystem 2 In Vivo Induced by Excess Irradiance. A Hypothesis Based on Changes in 77 K Fluorescence Spectra of Chlorophyll a in Barley Leaves

M. Čajánek, M. Hudcová, J. Kalina, I. Lachetová, V. Špunda

Photosynthetica 1999, 37(2):295 | DOI: 10.1023/A:1007168307931

Effects of short-term exposure to different irradiances on the function of photosystem 2 (PS2) were studied for barley grown at low (LI; 50 µmol m^-2 s^-1) and high (HI; 1 100 µmol m^-2 s^-1) irradiances. HI barley revealed higher ability to down-regulate the light-harvesting within PS2 after exposure to high irradiance as compared to LI plants. This ability was estimated from the light-induced decreases of F685/F742 and E476/E436 in emission and excitation spectra of 77 K chlorophyll (Chl) a fluorescence in vivo which was 65 and 10 % for HI plants as compared to 30 and 2 % for LI plants,...

Photoadaptation in the Green Alga Spongiochloris Sp. A Three-Fluorometer Study

M. Koblížek, M. Ciscato, J. Komenda, J. Kopecký, P. Šiffel, J. Masojídek

Photosynthetica 1999, 37(2):307-323 | DOI: 10.1023/A:1007120424769

The dark-adapted cells of the green alga Spongiochloris sp. were exposed to "white light" of 1000 µmol(photon) m^-2 s^-1 for 2 h and then dark adapted for 1.5 h. Changes of photochemical activities during photoadaptation were followed by measurement of chlorophyll (Chl) fluorescence kinetics, 77 K emission spectra, photosynthetic oxygen evolution, and pigment composition. We observed a build-up of slowly-relaxing non-photochemical quenching which led to a decrease of the F_v/F_m parameter and the connectivity. In contrast to the depression of F_v/F_m (35 %) and the rise of non-photochemical...

Vsevolodov, N.: Biomolecular Electronics

J. Nauš

Photosynthetica 1999, 37(2):324 | DOI: 10.1023/A:1007184711565

The Relation Between Changes in Non-Photochemical Quenching, Low Temperature Fluorescence Emission, and Membrane Ultrastructure Upon Binding of Polyionic Compounds and Fragments of Light-Harvesting Complex 2

D. Štys, P. Šiffel, I. Hunalová, J. Nebesářová

Photosynthetica 1999, 37(2):325 | DOI: 10.1023/A:1007172408839

Experiments were performed to distinguish some of the proposed mechanisms by which thylakoid membranes regulate the performance of photosynthetic apparatus in relation to non-photochemical quenching, q_N. Aliphatic diamines were used as uncouplers of transmembrane H⁺ gradient as they can be transported across the membrane at the expense of hydrogen cations. Diamines did not induce changes in low-temperature fluorescence emission but induced different changes in membrane ultrastructure. Positively charged peptides did not affect membrane ultrastructure but blocked q_N. In addition, they caused an increase of low temperature...

Relation Between the Heat-Induced Increase of F₀ Fluorescence and a Shift in the Electronic Equilibrium at the Acceptor Side of Photosystem 2

J.M. Ducruet

Photosynthetica 1999, 37(2):335-338 | DOI: 10.1023/A:1007124509748

F₀ fluorescence and thermoluminescence (TL) were recorded simultaneously on various dark-adapted leaf samples. Above 40 °C, a sharp peak of TL coincided with the onset of the heat-induced F₀ rise. It results from a back-transfer of an electron from the secondary Q_B ^-to the primary acceptor Q_A of photosystem 2, followed by a luminescence-emitting recombination with Tyr-D¹. This demonstrates that the critical temperature at which the F₀ starts rising also corresponds to a shift towards the left of the Q_A↔Q_B ^- equilibrium.