The polyphasic chlorophyll a fluorescence rise measured under high intensity of exciting light

Lazár, Dušan

doi:10.1071/fp05095

Cited by 308 publications

(214 citation statements)

References 171 publications

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“…Upon illumination the reaction centers gradually close until the electron acceptor molecules are fully reduced. This process is accompanied by a gradual increase in fluorescence yield, termed fast chlorophyll fluorescence rise, [20] where the emitted fluorescence represents the light that is not used for photosynthesis, and is thus 'wasted'. It is this 'wasted' light that is measured by PAM fluorometry.…”

Section: Modulated Micro-fluorometry Detects Optical Effects Of Cystomentioning

confidence: 99%

Certain Biominerals in Leaves Function as Light Scatterers

et al. 2012

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Cystoliths are amorphous calcium carbonate bodies that form in the leaves of some plant families. Cystoliths are regularly distributed in the epidermis and protrude into the photosynthetic tissue, the mesophyll. The photosynthetic pigments generate a steep light gradient in the leaf. Under most illumination regimes the outer mesophyll is light saturated, thus the photosynthetic apparatus is kinetically unable to use the excess light for photochemistry. Here we use micro‐scale modulated fluorometry to demonstrate that light scattered by the cystoliths is distributed from the photosynthetically inefficient upper tissue to the efficient, but light deprived, lower tissue. The results prove that the presence of light scatterers reduces the steep light gradient, thus enabling the leaf to use the incoming light flux more efficiently. MicroCT and electron microscopy confirm that the spatial distribution of the minerals is compatible with their optical function. During the study we encountered large calcium oxalate druses in the same anatomical location as the cystoliths. These druses proved to have similar light scattering functions as the cystoliths. This study shows that certain minerals in the leaves of different plants distribute the light flux more evenly inside the leaf.

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Section: Modulated Micro-fluorometry Detects Optical Effects Of Cystomentioning

confidence: 99%

Certain Biominerals in Leaves Function as Light Scatterers

et al. 2012

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“…The complimentary relation between fluorescence and photochemical yield has made fluorescence monitoring a sensitive non-invasive tool for probing the electron transport in PSII (Papageorgiou and Govindjee 2004). Several models have been presented which quantitatively relate the changes in fluorescence yield to the photochemical yield of electron transport to and from PSII (Bouges-Bocquet 1980;Stirbet et al 1998;Vredenberg 2000Vredenberg , 2004Lazár 2003Lazár , 2006Zhu et al 2005).…”

Section: Introductionmentioning

confidence: 99%

On the chlorophyll a fluorescence yield in chloroplasts upon excitation with twin turnover flashes (TTF) and high frequency flash trains

2007

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Chlorophyll fluorescence is routinely taken as a quantifiable measure of the redox state of the primary quinone acceptor Q A of PSII. The variable fluorescence in thylakoids increases in a single turnover flash (STF) from its low dark level F o towards a maximum F m STF when Q A becomes reduced. We found, using twin single turnover flashes (TTFs) that the fluorescence increase induced by the first twin-partner is followed by a 20-30% increase when the second partner is applied within 20-100 ls after the first one. The amplitude of the twin response shows a period-of-four oscillation associated with the 4-step oxidation of water in the Kok cycle (S states) and originates from two different trapped states with a life time of 0.2-0.4 and 2-5 ms, respectively. The oscillation is supplemented with a binary oscillation associated with the two-electron gate mechanism at the PSII acceptor side. The F(t) response in high frequency flash trains (1-4 kHz) shows (i) in the first 3-4 flashes a transient overshoot 20-30% above the F m STF = 3*F o level reached in the 1st flash with a partial decline towards a dip D in the next 2-3 ms, independent of the flash frequency, and (ii) a frequency independent rise to F m = 5*F o in the 3-60 ms time range. The initial overshoot is interpreted to be due to electron trapping in the S 0 fraction with Q B -nonreducing centers and the dip to the subsequent recovery accompanying the reoxidation of the double reduced acceptor pair in these RCs after trapping. The rise after the overshoot is, in agreement with earlier findings, interpreted to indicate a photo-electrochemical control of the chlorophyll fluorescence yield of PSII. It is anticipated that the double exciton and electron trapping property of PSII is advantageous for the plant. It serves to alleviate the depression of electron transport in single reduced Q B -nonreducing RCs, associated with electrochemically coupled proton transport, by an increased electron trapping efficiency in these centers.Keywords Chlorophyll a Á Fluorescence quenching Á Q B -nonreducing center Á Single turnover excitation Á Twin turnover excitation Á Three state trapping mechanism (TSTM)

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“…The K peak (at 300 ls) is a well-documented symptom of heat stress, and is thought to indicate the separation of the OEC complex and electron transport between pheophytin and primary electron acceptor Q A (Strasser et al 2000;Lazár 2006). In wheat, a treatment at 35°C had no affect on photosynthetic efficiency, while exposure to 45°C caused irreversible damage to the OEC .…”

Section: Temperature Effectsmentioning

confidence: 99%

Chlorophyll a fluorescence as a tool to monitor physiological status of plants under abiotic stress conditions

et al. 2016

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Plants living under natural conditions are exposed to many adverse factors that interfere with the photosynthetic process, leading to declines in growth, development, and yield. The recent development of Chlorophyll a fluorescence (ChlF) represents a potentially valuable new approach to study the photochemical efficiency of leaves. Specifically, the analysis of fluorescence signals provides detailed information on the status and function of Photosystem II (PSII) reaction centers, lightharvesting antenna complexes, and both the donor and acceptor sides of PSII. Here, we review the results of fast ChlF analyses of photosynthetic responses to environmental stresses, and discuss the potential scientific and practical applications of this innovative methodology. The recent availability of portable devices has significantly expanded the potential utilization of ChlF techniques, especially for the purposes of crop phenotyping and monitoring.

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The polyphasic chlorophyll a fluorescence rise measured under high intensity of exciting light

Cited by 308 publications

References 171 publications

Certain Biominerals in Leaves Function as Light Scatterers

Certain Biominerals in Leaves Function as Light Scatterers

On the chlorophyll a fluorescence yield in chloroplasts upon excitation with twin turnover flashes (TTF) and high frequency flash trains

Chlorophyll a fluorescence as a tool to monitor physiological status of plants under abiotic stress conditions

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