On the polyphasic quenching kinetics of chlorophyll a fluorescence in algae after light pulses of variable length

0422526 - MBÚ 2014 RIV NL eng J - Journal Article
Vredenberg, W. - Prášil, Ondřej
On the polyphasic quenching kinetics of chlorophyll a fluorescence in algae after light pulses of variable length.
Photosynthesis Research. Roč. 117, 1-3 (2013), s. 321-337. ISSN 0166-8595. E-ISSN 1573-5079
R&D Projects: GA MŠMT(CZ) ED2.1.00/03.0110
Institutional support: RVO:61388971
Keywords : Chlorophyll a fluorescence * Photosystem II * Quenching kinetics
Subject RIV: EE - Microbiology, Virology
Impact factor: 3.185, year: 2013

This study reports on kinetics of the fluorescence decay in a suspension of the alga Scenedesmus quadricauda after actinic illumination. These are monitored as the variable fluorescence signal in the dark following light pulses of variable intensity and duration. The decay reflects the restoration of chlorophyll fluorescence quenching of the photosystem II (PSII) antennas and shows a polyphasic pattern which suggests the involvement of different processes. The overall quenching curve after a fluorescence-saturating pulse (SP) of 250-ms duration, commonly used in pulse amplitude modulation applications as the tool for estimating the maximal fluorescence (F (m)), has been termed P-O, in which P and O have the same meaning as used in the OJIP induction curve in the light. Deconvolution of this signal shows at least three distinguishable exponential phases with reciprocal rate constants of the order of 10, 10(2), and 10(3) ms. The size of the long (> 10(3) ms) and moderate (10(2) ms) lasting components relative to the complete quenching signal after an SP increases with the duration of the actinic pulse concomitantly with an increase in the reciprocal rate constants of the fast (10 ms) and moderate quenching phases. Fluorescence responses upon single turnover flashes of 30-mu s duration (STFs) given at discrete times during the P-O quenching were used as tools for identifying the quencher involved in the P-O quenching phase preceding the STF excitation. Results are difficult to interpret in terms of a single-hit two-state trapping mechanism with distinguishable quenching properties of open and closed reaction centers only.
Permanent Link: http://hdl.handle.net/11104/0228740