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12. Irreversible changes in barley leaf chlorophyll fluorescence detected by the fluorescence temperature curve in a linear heating/cooling regime

Creator:
Frolec, J., Ilík, P., Krchňák, P., Sušila, P., and Nauš, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
heat stress and Hordeum
Language:
Multiple languages
Description:
The chlorophyll fluorescence (F) temperature curves in a linear time-temperature heating/cooling regime were used to study heat-induced irreversible F changes in primary green leaves of spring barley (Hordeum vulgare L. cv. Akcent). The leaf segments were heated in a stirred water bath at heating rates of 0.0083, 0.0166, 0.0333, and 0.0500 °C s-1 from room temperature up to maximal temperature Tm and then linearly cooled to 35 °C at the same rate. The F intensity was measured by a pulse-modulated technique. The results support the existence of the two critical temperatures of irreversible F changes postulated earlier, at 45-48 and 53-55 °C. The critical temperatures are slightly dependent on the heating rate. Two types of parameters were used to characterize the irreversibility of the F changes: the coefficient of irreversibility μ defined as the ratio of F intensity at 35 °C at the starting/ending parts of the cycle and the slopes of tangents of linear parts of the F temperature curve. The dependence of μ on T m revealed a maximum, which moved from 54 to 61 °C with the increasing heating/cooling rate v from 0.0083 to 0.0500 °C s-1, showing two basic phases of the irreversible changes. The Arrhenius and Eyring approaches were applied to calculate the activation energies of the initial increase in μ. The values varied between 30 and 50 kJ mol-1 and decreased slightly with the increasing heating rate. and J. Frolec ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

14. Mechanical wounding caused by inoculation influences the photosynthetic response of Nicotiana benthamiana plants to plum pox potyvirus

Creator:
Hlaváčková, V., Špundová, M., Nauš, J., Navrátil, M., Kouřil, R., and Kaňa, R.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, CO2 assimilation, ELISA-DASI, systemic response, net photosynthetic rate, thermoluminescence, tobacco, and viral infection
Language:
Multiple languages
Description:
Plants of Nicotiana benthamiana (Gray) (60 d old) were mechanically inoculated by a spreading of the fourth and fifth leaves with inoculum with or without plum pox potyvirus (PPV). Changes in growth parameters and selected photosynthetic characteristics were followed in control and inoculated plants in the locally affected leaves (LA) during 11 d after inoculation (DAI), in systemically affected leaves immature at time of inoculation (SAI) during 14-25 DAI, and in systemically affected leaves developed after the inoculation (SAD) during 28-39 DAI. The pure mechanical damage caused by inoculation induced a decrease in the net photosynthetic rate (PN) in LA and SAD leaves, and an increase in the steady-state value of the non-photochemical chlorophyll (Chl) fluorescence quenching qN. The qN increase appeared in certain time intervals in all measured leaves on plants, so it could be regarded as indication of a systemic reaction of plant to the local mechanical injury. The viral infection developed in LA leaves and spread to SAI and SAD leaves was documented by the ELISA-DASI method. The plant height and area of SAI and SAD leaves were lower in infected plants. The combined effect of mechanical damage and viral infection caused a decrease in PN only in LA and SAD leaves. In SAD leaves, an increased relative height of the J step (VJ) in the O-J-I-P Chl fluorescence transient together with a lower B/A band ratio of thermoluminescence glow curves reflected a damage to the acceptor side of photosystem 2 (PS2) caused by the viral infection, and a faster kinetics of the induction of the photochemical quenching coefficient qP of Chl fluorescence indicated a faster QA- re-oxidation in the remaining undamaged centres of PS2. and V. Hlaváčková ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

15. Moderately elevated temperature eliminates resistance of rice plants with enhanced expression of glutathione reductase to intensive photooxidative stress

Creator:
Kouřil, R., Lazár, D., Lee, H., Jo, J., and Nauš, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
active oxygen species, chlorophyll fluorescence, Oryza sativa, photochemical and non-photochemical fluorescence quenching, and transgenic plants
Language:
Multiple languages
Description:
We developed transgenic rice plants (Oryza sativa L. cv. Daeribbyeo) overproducing cytosolic glutathione reductase (GR) using a GR gene from Brassica campestris and studied their response to photo-oxidative stress in the presence of methyl viologen (MV, 10 and 50 μM concentrations) under room (25 °C) and moderately elevated (35 °C) temperature by analysis of chlorophyll (Chl) a fluorescence parameters (FV/FM, qN, and qP) and of Chl content. Elevated temperature enhanced and accelerated the photo-oxidative damage to photosynthetic apparatus expressed mainly by a fast decrease of qN. Higher temperature supported the protective reaction in transformed rice plants for lower MV concentration (10 μM) and eliminated the enhanced tolerance of photosystem 2 photochemistry to photooxidative stress for higher (50 μM) MV concentration. Different mechanisms and temperature dependence of oxidative and protective reactions explain the results. and R. Kouřil ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

17. Plant shading increases lipid peroxidation and intensifies senescence-induced changes in photosynthesis and activities of ascorbate peroxidase and glutathione reductase in wheat

Creator:
Špundová, M., Slouková, K., Hunková, M., and Nauš, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
ageing, chlorophyll fluorescence, CO2 assimilation, plant topography, and Triticum aestivum
Language:
Multiple languages
Description:
Plants of spring wheat (Triticum aestivum L. cv. Saxana) were grown during the autumn. Over the growth phase of three leaves (37 d after sowing), some of the plants were shaded and the plants were grown at 100 (control without shading), 70, and 40 % photosynthetically active radiation. Over 12 d, chlorophyll (Chl) and total protein (TP) contents, rate of CO2 assimilation (PN), maximal efficiency of photosystem 2 photochemistry (FV/FP), level of lipid peroxidation, and activities of antioxidative enzymes ascorbate peroxidase (APX) and glutathione reductase (GR) were followed in the 1st, 2nd, and 3rd leaves (counted according to their emergence). In un-shaded plants, the Chl and TP contents, PN, and FV/FP decreased during plant ageing. Further, lipid peroxidation increased, while the APX and GR activities related to the fresh mass (FM) decreased. The APX activity related to the TP content increased in the 3rd leaves. The plant shading accelerated senescence including the increase in lipid peroxidation especially in the 1st leaves and intensified the changes in APX and GR activities. We suggest that in the 2nd and 3rd leaves a degradation of APX was slowed down, which could reflect a tendency to maintain the antioxidant protection in chloroplasts of these leaves. and M. Špundová ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

18. Responses of photosystem 2 photochemistry and pigment compositíon in needles of Norway spruce saplings to increased radiation level

Creator:
Špunda, V., Kalina, J., Nauš, J., Kuropatwa, R., Mašláň, M., and Marek, M.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
o reveal the dynamics of short-term photosynthetic acclimation to increased irradiance, the light response of photochemical (qp), non-photochemical (q^) and Fo (qo) quenchings of chlorophyll (Chl) fluorescence and Chl and carotenoids compositíon in Norway spruce needles were monitored within three days after transfer of saplings ffom low diffuse irradiance (maximum photosynthetic photon fluence density PPFD 50 pmol m'^ s'i) to direct sun radiation (maximum PPFD 2000 pmol m‘2 s'*). Irradiance responses of fluorescence quenching coefficients revealed the occurrence of substantíal changes in partítioning of excitation energy between photochemical reactions and radiatíonless dissipation within two days. The saturating irradiance for qj,j and the capacity of non-radiatíve dissipation processes was shifted from about 450 pmol m'^ s** to 1620 pmol m-2 s'L Whereas immediately after exposure to ťull sunlight was completely reduced at 1620 pmol m'^ s'*, two days later 40 % of was stíll present in oxidized form at this irradiance. A fast pigment photobleaching at noon prevented the over-reduction of and thus it was one of the possible short-term acclimation processes. No severe photoinhibition of photosystem 2 (PS 2) photochemistry occurred within the period of investigation as can be judged from the high F^/F^ value.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

19. Statistical properties of chlorophyll fluorescence induction parameters

Creator:
Lazár, D. and Nauš, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Gaussian distribution, leaf age, Triticum aestivum, and wheat
Language:
Multiple languages
Description:
Parameters of the fast chlorophyll (Chl) fluorescence induction (the O-J-I-P curve) of plants of winter wheat grown in the field canopy were statistically tested for Gaussian distribution. Five different statistical methods showed that the obtained values did not obey the Gaussian distribution law. The presentation of the parameters with the help of the mean and standard deviation masks the information about statistical properties of the values. Thus, we recommend to present the parameters by means of median, quartiles, and minimum and maximum values rather than by means of the mean and standard deviation. and D. Lazár, J. Nauš.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

20. The gradient of exciting radiation within a sample affects the relative height of steps in the fast chlorophyll a fluorescence rise

Creator:
Sušila, P., Lazár, D., Ilík, P., Tomek, P., and Nauš, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
exciting irradiance gradient, model, O-J-I-P transient, optical property, and Pisum
Language:
Multiple languages
Description:
Measurement of the chlorophyll (Chl) a fluorescence rise (FR) under higher exciting irradiance (EI), the O-J-I-P transient, or under lower irradiance, the O-I-P transient, is a routinely used method to access photosystem 2 function in thylakoid membranes of chloroplasts. Our measurements with a suspension of pea thylakoid membranes showed that the relative heights of the J and I steps in the FR depended not only on EI but also on the concentration and thickness of the sample. We explain this effect as a consequence of the gradient of EI within the sample. We tested this suggestion by theoretical simulations of the FR based on the model that was previously used for simulation of the FR considering in addition the gradient of EI within the sample. Our theoretical results correspond well with the experiments. The irradiance gradient effect may influence measured FR significantly and this fact should be taken into consideration in the interpretation of measured FRs. and P. Sušila ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public