Journal
JOURNAL OF PLANT PHYSIOLOGY
Volume 226, Issue -, Pages 40-47Publisher
ELSEVIER GMBH, URBAN & FISCHER VERLAG
DOI: 10.1016/j.jplph.2018.03.020
Keywords
Chloroplastic ATP synthase; Cyclic electron flow; Fluctuating light; Non-photochemical quenching; Photosynthetic control; Proton motive force
Categories
Funding
- National Natural Science Foundation of China [31670343]
- Youth Innovation Promotion Association of the Chinese Academy of Sciences [2016347]
- Major Science and Technique Programs in Yunnan Province [2016ZF001]
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The proton motive force (pmf) across the thylakoid membranes plays a key role for photosynthesis in fluctuating light. However, the mechanisms underlying the regulation of pmf in fluctuating light are not well known. In this study, we aimed to identify the roles of chloroplastic ATP synthase and cyclic electron flow (CEF) around photosystem I (PSI) in the regulation of the pmf in fluctuating light. To do this, we measured chlorophyll fluorescence, P700 parameters, and the electrochromic shift signal in the fluctuating light alternating between 918 (high light) and 89 (low light) mu mol photons m(-2) s(-1) every 5 min. We found that the activity of chloroplastic ATP synthase (g(H)(+)), pmf, CEF activity, non-photochemical quenching (NPQ), and the P700 redox state changed rapidly in fluctuating light. During transition from low to high light, the decreased g(H)(+) and the stimulation of CEF both contributed to the rapid formation of pmf, activating NPQ and optimizing the redox state of P700 in PSI. During the low-light phases, g(H)(+) rapidly increased and the pmf declined sharply, leading to the relaxation of NPQ and down-regulation of photosynthetic control. These findings indicate that in fluctuating light the g(H)(+) and CEF are finely regulated to modulate the pmf formation, avoiding the over-accumulation of reactive intermediates and maximizing energy use efficiency.
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