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A simple routine for quantitative analysis of light and dark kinetics of photochemical and non-photochemical quenching of chlorophyll fluorescence in intact leaves.

Vredenberg W - Photosyn. Res. (2015)

Bottom Line: Paper describes principles and application of a novel routine that enables the quantitative analysis of the photochemical O-J phase of the variable fluorescence F v associated with the reversible photo-reduction of the secondary electron acceptor QA of photosystem II (PSII) in algae and intact leaves.Application of these pulses allows estimations of (i) the actual value of the rate constants k L and k AB of the light excitation (photoreduction of QA) and of the dark re-oxidation of photoreduced QA ([Formula: see text]), respectively, (ii) the actual maximal normalized variable fluorescence [nF v] associated with 100 % photoreduction of QA of open RCs, and (iii) the actual size β of RCs in which the re-oxidation of [Formula: see text] is largely suppressed (QB-nonreducing RC with k AB ~ 0).The kinetics of fluorescence changes during and after the I-P phase are given special attention in relation to the hypothesis on the involvement of a Δµ H+-dependent effect during this phase and thereafter.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Physiology, Wageningen University and Research, Wageningen, The Netherlands, wim@vredenberg.nl.

ABSTRACT
Paper describes principles and application of a novel routine that enables the quantitative analysis of the photochemical O-J phase of the variable fluorescence F v associated with the reversible photo-reduction of the secondary electron acceptor QA of photosystem II (PSII) in algae and intact leaves. The kinetic parameters that determine the variable fluorescence F (PP)(t) associated with the release of photochemical quenching are estimated from 10 µs time-resolved light-on and light-off responses of F v induced by two subsequent light pulses of 0.25 (default) and 1000 ms duration, respectively. Application of these pulses allows estimations of (i) the actual value of the rate constants k L and k AB of the light excitation (photoreduction of QA) and of the dark re-oxidation of photoreduced QA ([Formula: see text]), respectively, (ii) the actual maximal normalized variable fluorescence [nF v] associated with 100 % photoreduction of QA of open RCs, and (iii) the actual size β of RCs in which the re-oxidation of [Formula: see text] is largely suppressed (QB-nonreducing RC with k AB ~ 0). The rate constants of the dark reversion of Fv associated with the release of photo-electrochemical quenching F (PE) and photo-electric stimulation F (CET) in the successive J-I and I-P parts of the thermal phase are in the range of (100 ms)(-1) and (1 s)(-1), respectively. The kinetics of fluorescence changes during and after the I-P phase are given special attention in relation to the hypothesis on the involvement of a Δµ H+-dependent effect during this phase and thereafter. Paper closes with author's personal view on the demands that should be fulfilled for chlorophyll fluorescence methods being a correct and unchallenged signature of photosynthesis in algae and plants.

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Linear time plot, similar as in Fig. 9, except for ten-fold attenuation of pulse intensity and plant (leaf) species, of Fexp(t) in a Arum italliensis leaf upon a 500 ms (s) SP500 and a 1 s SP, both of 300 µmol photons m−2 s−1 intensity. Here the blue dashed line is the decay of the sSP100 response. Meaning of symbolsand labeled curves is the same as in Fig. 9
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Fig10: Linear time plot, similar as in Fig. 9, except for ten-fold attenuation of pulse intensity and plant (leaf) species, of Fexp(t) in a Arum italliensis leaf upon a 500 ms (s) SP500 and a 1 s SP, both of 300 µmol photons m−2 s−1 intensity. Here the blue dashed line is the decay of the sSP100 response. Meaning of symbolsand labeled curves is the same as in Fig. 9

Mentions: Figure 10 shows the same experiment as Fig. 9 but done at a tenfold lower intensity of the actinic light pulse and in a leaf of a different plant species. The results on the light response at low(er) intensities are in agreement with those of similar experiments in many other plant species (Strasser et al. 1995; Lazár 2006; Schansker et al. 2006; Vredenberg 2011) and demonstrate (i) an apparent increase of FCET, a much lower OI phase (FPP + FPE) and, (iii) nearly the same Fm as compared to values at a tenfold higher intensity shown in Fig. 9. However, the slow (k4) component of the decay is as large as observed at the higher intensity in Fig. 9. This observation, as will be discussed later, hints to the conclusion that the de-quenching process responsible for the IP phase is mechanistically different from those of the O–J–I phase.Fig. 10


A simple routine for quantitative analysis of light and dark kinetics of photochemical and non-photochemical quenching of chlorophyll fluorescence in intact leaves.

Vredenberg W - Photosyn. Res. (2015)

Linear time plot, similar as in Fig. 9, except for ten-fold attenuation of pulse intensity and plant (leaf) species, of Fexp(t) in a Arum italliensis leaf upon a 500 ms (s) SP500 and a 1 s SP, both of 300 µmol photons m−2 s−1 intensity. Here the blue dashed line is the decay of the sSP100 response. Meaning of symbolsand labeled curves is the same as in Fig. 9
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4368846&req=5

Fig10: Linear time plot, similar as in Fig. 9, except for ten-fold attenuation of pulse intensity and plant (leaf) species, of Fexp(t) in a Arum italliensis leaf upon a 500 ms (s) SP500 and a 1 s SP, both of 300 µmol photons m−2 s−1 intensity. Here the blue dashed line is the decay of the sSP100 response. Meaning of symbolsand labeled curves is the same as in Fig. 9
Mentions: Figure 10 shows the same experiment as Fig. 9 but done at a tenfold lower intensity of the actinic light pulse and in a leaf of a different plant species. The results on the light response at low(er) intensities are in agreement with those of similar experiments in many other plant species (Strasser et al. 1995; Lazár 2006; Schansker et al. 2006; Vredenberg 2011) and demonstrate (i) an apparent increase of FCET, a much lower OI phase (FPP + FPE) and, (iii) nearly the same Fm as compared to values at a tenfold higher intensity shown in Fig. 9. However, the slow (k4) component of the decay is as large as observed at the higher intensity in Fig. 9. This observation, as will be discussed later, hints to the conclusion that the de-quenching process responsible for the IP phase is mechanistically different from those of the O–J–I phase.Fig. 10

Bottom Line: Paper describes principles and application of a novel routine that enables the quantitative analysis of the photochemical O-J phase of the variable fluorescence F v associated with the reversible photo-reduction of the secondary electron acceptor QA of photosystem II (PSII) in algae and intact leaves.Application of these pulses allows estimations of (i) the actual value of the rate constants k L and k AB of the light excitation (photoreduction of QA) and of the dark re-oxidation of photoreduced QA ([Formula: see text]), respectively, (ii) the actual maximal normalized variable fluorescence [nF v] associated with 100 % photoreduction of QA of open RCs, and (iii) the actual size β of RCs in which the re-oxidation of [Formula: see text] is largely suppressed (QB-nonreducing RC with k AB ~ 0).The kinetics of fluorescence changes during and after the I-P phase are given special attention in relation to the hypothesis on the involvement of a Δµ H+-dependent effect during this phase and thereafter.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Physiology, Wageningen University and Research, Wageningen, The Netherlands, wim@vredenberg.nl.

ABSTRACT
Paper describes principles and application of a novel routine that enables the quantitative analysis of the photochemical O-J phase of the variable fluorescence F v associated with the reversible photo-reduction of the secondary electron acceptor QA of photosystem II (PSII) in algae and intact leaves. The kinetic parameters that determine the variable fluorescence F (PP)(t) associated with the release of photochemical quenching are estimated from 10 µs time-resolved light-on and light-off responses of F v induced by two subsequent light pulses of 0.25 (default) and 1000 ms duration, respectively. Application of these pulses allows estimations of (i) the actual value of the rate constants k L and k AB of the light excitation (photoreduction of QA) and of the dark re-oxidation of photoreduced QA ([Formula: see text]), respectively, (ii) the actual maximal normalized variable fluorescence [nF v] associated with 100 % photoreduction of QA of open RCs, and (iii) the actual size β of RCs in which the re-oxidation of [Formula: see text] is largely suppressed (QB-nonreducing RC with k AB ~ 0). The rate constants of the dark reversion of Fv associated with the release of photo-electrochemical quenching F (PE) and photo-electric stimulation F (CET) in the successive J-I and I-P parts of the thermal phase are in the range of (100 ms)(-1) and (1 s)(-1), respectively. The kinetics of fluorescence changes during and after the I-P phase are given special attention in relation to the hypothesis on the involvement of a Δµ H+-dependent effect during this phase and thereafter. Paper closes with author's personal view on the demands that should be fulfilled for chlorophyll fluorescence methods being a correct and unchallenged signature of photosynthesis in algae and plants.

Show MeSH
Related in: MedlinePlus