TY - JOUR
T1 - The slow S to M rise of chlorophyll a fluorescence reflects transition from state 2 to state 1 in the green alga Chlamydomonas reinhardtii
AU - Kodru, Sireesha
AU - Malavath, Tirupathi
AU - Devadasu, Elsinraju
AU - Nellaepalli, Sreedhar
AU - Stirbet, Alexandrina
AU - Subramanyam, Rajagopal
AU - Govindjee,
N1 - Funding Information:
Rajagopal Subramanyam was supported by the Department of Biotechnology (BT/PR15132/BRB/10/909/2011) and the Council of Scientific and Industrial Research (38(1381)/14/EMR-II), India, and Sireesha Kodru by the Department of Biotechnology for a research associate fellowship (DBT-RA), India. Govindjee was supported by the US Fulbright foundation during his stay at the University of Hyderabad, India. We are grateful to Reto J. Strasser and to the late Prasanna Mohanty for providing the Handy PEA instrument used in our studies. We thank Vandana Chakravartty of the University of Illinois at Urbana-Champaign for her valuable comments during the preparation of this manuscript.
Publisher Copyright:
© 2015 Springer Science+Business Media 2015.
PY - 2015/8/17
Y1 - 2015/8/17
N2 - The green alga Chlamydomonas (C.) reinhardtii is a model organism for photosynthesis research. State transitions regulate redistribution of excitation energy between photosystem I (PS I) and photosystem II (PS II) to provide balanced photosynthesis. Chlorophyll (Chl) a fluorescence induction (the so-called OJIPSMT transient) is a signature of several photosynthetic reactions. Here, we show that the slow (seconds to minutes) S to M fluorescence rise is reduced or absent in the stt7 mutant (which is locked in state 1) in C. reinhardtii. This suggests that the SM rise in wild type C. reinhardtii may be due to state 2 (low fluorescence state; larger antenna in PS I) to state 1 (high fluorescence state; larger antenna in PS II) transition, and thus, it can be used as an efficient and quick method to monitor state transitions in algae, as has already been shown in cyanobacteria (Papageorgiou et al. 1999, 2007; Kaňa et al. 2012). We also discuss our results on the effects of (1) 3-(3,4-dichlorophenyl)-1,4-dimethyl urea, an inhibitor of electron transport; (2) n-propyl gallate, an inhibitor of alternative oxidase (AOX) in mitochondria and of plastid terminal oxidase in chloroplasts; (3) salicylhydroxamic acid, an inhibitor of AOX in mitochondria; and (4) carbonyl cyanide p-trifluoromethoxyphenylhydrazone, an uncoupler of phosphorylation, which dissipates proton gradient across membranes. Based on the data presented in this paper, we conclude that the slow PSMT fluorescence transient in C. reinhardtii is due to the superimposition of, at least, two phenomena: qE dependent non-photochemical quenching of the excited state of Chl, and state transitions.
AB - The green alga Chlamydomonas (C.) reinhardtii is a model organism for photosynthesis research. State transitions regulate redistribution of excitation energy between photosystem I (PS I) and photosystem II (PS II) to provide balanced photosynthesis. Chlorophyll (Chl) a fluorescence induction (the so-called OJIPSMT transient) is a signature of several photosynthetic reactions. Here, we show that the slow (seconds to minutes) S to M fluorescence rise is reduced or absent in the stt7 mutant (which is locked in state 1) in C. reinhardtii. This suggests that the SM rise in wild type C. reinhardtii may be due to state 2 (low fluorescence state; larger antenna in PS I) to state 1 (high fluorescence state; larger antenna in PS II) transition, and thus, it can be used as an efficient and quick method to monitor state transitions in algae, as has already been shown in cyanobacteria (Papageorgiou et al. 1999, 2007; Kaňa et al. 2012). We also discuss our results on the effects of (1) 3-(3,4-dichlorophenyl)-1,4-dimethyl urea, an inhibitor of electron transport; (2) n-propyl gallate, an inhibitor of alternative oxidase (AOX) in mitochondria and of plastid terminal oxidase in chloroplasts; (3) salicylhydroxamic acid, an inhibitor of AOX in mitochondria; and (4) carbonyl cyanide p-trifluoromethoxyphenylhydrazone, an uncoupler of phosphorylation, which dissipates proton gradient across membranes. Based on the data presented in this paper, we conclude that the slow PSMT fluorescence transient in C. reinhardtii is due to the superimposition of, at least, two phenomena: qE dependent non-photochemical quenching of the excited state of Chl, and state transitions.
KW - Chlorophyll fluorescence
KW - Light-harvesting complex
KW - Photosystem I
KW - Photosystem II
KW - State transitions
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U2 - 10.1007/s11120-015-0084-2
DO - 10.1007/s11120-015-0084-2
M3 - Article
C2 - 25663564
AN - SCOPUS:84931578231
VL - 125
SP - 219
EP - 231
JO - Photosynthesis Research
JF - Photosynthesis Research
SN - 0166-8595
IS - 1-2
ER -