Thylakoid plasticity primes photoprotection in diatoms

For many millions of years, diatoms have been major primary producers in marine ecosystems, supporting food webs and contributing to carbon sequestration through the export of photosynthetically fixed carbon to the deep ocean, mitigating atmospheric carbon dioxide levels and global climate. A key factor in their ecological success is their ability to rapidly adapt to fluctuating light, balancing efficient light harvesting under dim conditions with energy dissipation under excess light. However, the mechanisms behind this regulation have not been fully elucidated. This study shows that several processes contribute to dissipating excess excitation energy in diatoms exposed to light stress: (i) the detachment of the oxygen-evolving complex proteins from the PSII core, leading to energy dissipation via charge recombination, (ii) Non-Photochemical Quenching (NPQ) in the antenna, i.e., thermal dissipation of excited states and (iii) excitation energy transfer from PSII to PSI via energy spillover. The latter process is observed in parallel with high light-induced topological changes of the thylakoids that may favor transient interactions between the photosystems. Along with the accumulation of light-stress-protecting carotenoids on longer time-scales, this ensemble of photoprotective mechanisms provides a dynamic and flexible response to the light challenges expected in coastal marine habitats.

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Publication Details

Journal
bioRxiv (Cold Spring Harbor Laboratory)
Published
2026-10-29
DOI
https://doi.org/10.64898/2026.10.27.761787
Primary Topic
Photosynthetic Processes and Mechanisms
Type
preprint

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preprint

Thylakoid plasticity primes photoprotection in diatoms

Cécile Giustini, Pascal Albanese, Serena Flori, Gergely Nagy et al.
1 links
bioRxiv (Cold Spring Harbor Laboratory)
Photosynthetic Processes and Mechanisms
preprint

Thylakoid plasticity primes photoprotection in diatoms

Cécile Giustini, Pascal Albanese, Serena Flori, Gergely Nagy, Wojciech Wietrzyñski, Giovanni Finazzi, Anja Krieger‐Liszkay, Christine Moriscot, Renáta Ünnep, Daphna Fenel, Benjamin D. Engel, Guy Schoehn, Clarisse Uwizeye, Dimitri Tolleter, Lydia Pernet, Pierre‐Henri Jouneau, David Pérez Compte, Győző Garab
preprint en

Abstract

For many millions of years, diatoms have been major primary producers in marine ecosystems, supporting food webs and contributing to carbon sequestration through the export of photosynthetically fixed carbon to the deep ocean, mitigating atmospheric carbon dioxide levels and global climate. A key factor in their ecological success is their ability to rapidly adapt to fluctuating light, balancing efficient light harvesting under dim conditions with energy dissipation under excess light. However, the mechanisms behind this regulation have not been fully elucidated. This study shows that several processes contribute to dissipating excess excitation energy in diatoms exposed to light stress: (i) the detachment of the oxygen-evolving complex proteins from the PSII core, leading to energy dissipation via charge recombination, (ii) Non-Photochemical Quenching (NPQ) in the antenna, i.e., thermal dissipation of excited states and (iii) excitation energy transfer from PSII to PSI via energy spillover. The latter process is observed in parallel with high light-induced topological changes of the thylakoids that may favor transient interactions between the photosystems. Along with the accumulation of light-stress-protecting carotenoids on longer time-scales, this ensemble of photoprotective mechanisms provides a dynamic and flexible response to the light challenges expected in coastal marine habitats.

bioRxiv (Cold Spring Harbor Laboratory)
Centre National de la Recherche Scientifique (FR), University of Basel (CH), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), HUN-REN Szegedi Biológiai Kutatóközpont (HU), CEA Paris-Saclay - Etablissement de Saclay (FR), Paul Scherrer Institute (CH), Institut des Neurosciences Paris-Saclay (FR), Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (FR), Institut de Recherche Interdisciplinaire de Grenoble (FR), Institute for Energy Security and Environmental Safety (HU), Laboratoire Physiologie Cellulaire & Végétale (FR), Institute of Plant Biology (HU), European Molecular Biology Laboratory (DE), Institut de Biologie Structurale (FR), European Molecular Biology Laboratory (DE), Budapest Neutron Centre (HU), HUN-REN Centre for Energy Research (HU), Hungarian Research Network (HU), Université Grenoble Alpes (FR)
U.S. Department of Energy, European Commission, Agence Nationale de la Recherche, Hungarian Scientific Research Fund, Office of Science, Oak Ridge National Laboratory, HORIZON EUROPE European Innovation Council
Photosynthetic Processes and Mechanisms
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