Delayed fluorescence in photosynthesis

Abstract

Photosynthesis is a very efficient photochemical process. Nevertheless, plants emit some of the absorbed energy as light quanta. This luminescence is emitted, predominantly, by excited chlorophyll a molecules in the light-harvesting antenna, associated with Photosystem II (PS II) reaction centers. The emission that occurs before the utilization of the excitation energy in the primary photochemical reaction is called prompt fluorescence. Light emission can also be observed from repopulated excited chlorophylls as a result of recombination of the charge pairs. In this case, some time-dependent redox reactions occur before the excitation of the chlorophyll. This delays the light emission and provides the name for this phenomenon-delayed fluorescence (DF), or delayed light emission (DLE). The DF intensity is a decreasing polyphasic function of the time after illumination, which reflects the kinetics of electron transport reactions both on the (electron) donor and the (electron) acceptor sides of PS II. Two main experimental approaches are used for DF measurements: (a) recording of the DF decay in the dark after a single turnover flash or after continuous light excitation and (b) recording of the DF intensity during light adaptation of the photosynthesizing samples (induction curves), following a period of darkness. In this paper we review historical data on DF research and recent advances in the understanding of the relation between the delayed fluorescence and specific reactions in PS II. An experimental method for simultaneous recording of the induction transients of prompt and delayed chlorophyll fluorescence and decay curves of DF in the millisecond time domain is discussed.

Chlorophyll fluorescence in the evaluation of photosynthetic electron transport chain inhibitors in the pea

“…Just as the chlorophylls of the PSII antenna emit a fluorescence transient signal, they also emit an DF signal, this being a result of the reversal of charge separation followed by the transfer of energy from the rapid excitation of the excited P 680 to the antenna chlorophylls (GOLTSEV et al, 2009). According to Goltsev et a l. ( 2009), DF kinetics comprises various components, each with a different duration and amplitude, being emitted due to the return of the electron transfer and to the charge recombination of various redox states of PSII, such as P 680 + Pheo -, P 680…”

“…However, just as the chlorophylls of the PSII emit light as FT, they also emit another type of light, known as delayed fluorescence (DF), as a result of the reversal of charge separation followed by the rapid transfer of P 680 * excitation energy to the chlorophylls of the antenna system (GOLTSEV et al, 2009;STRASSER, 2013;STRASSER et al, 2010).…”

“…To distinguish the two types of light emission, FT is measured at the same time as illumination, while DF is measured after the actinic light is turned off, in alternating cycles of light and dark (GOLTSEV et al, 2009;STRASSER, 2013). According to Grabolle and Dau (2005), the similarity between the spectral emissions of FT and DF shows that the emitted photon is the result of the radioactive deactivation of the excited state of the PSII Chl.…”

Biophotons, coherence and photocount statistics: A critical review

“…Therefore, conclusions from the study of physical parameters of delayed luminescence cannot be directly used to prove parameters of autoluminescence. [123,120] Delayed luminescence in plants is usually interpreted as a consequence of the complex reactions involved in photosystem II [125]. Experimental delayed luminescence can then be reproduced using reasonable reaction constants [126].…”

Berger C. Mayne (1920–2011): a friend and his contributions to photosynthesis research

“…These observations provided information on the S-state (of the Oxygen Evolving Complex, OEC) that was the probable precursor of the chemically induced luminescence. Goltsev et al (2009) have reviewed the current ideas about the relation of delayed fluorescence to the redox states of the chloroplast donors and acceptors.…”