Chlamydomonas reinhardtii Exhibits De Facto Constitutive NPQ Capacity in Physiologically Relevant Conditions

Wojciech J. Nawrocki, Xin Liu, Roberta Croce

Research output: Contribution to JournalArticleAcademicpeer-review


The photosynthetic apparatus must be able to withstand light conditions that exceed its capacity for carbon fixation. Photosynthetic organisms developed nonphotochemical quenching (NPQ), a process that dissipates excess absorbed light energy as heat and limits the production of reactive oxygen species and cellular damage. In the green alga Chlamydomonas reinhardtii, the LHCSR pigment-binding proteins are essential for NPQ. These complexes are not constitutively present in the thylakoid membranes; however, in laboratory conditions their expression depends on prior high light exposure of cells. To investigate the role of NPQ, we measured cells grown under a day-night cycle with a high light peak at mid-day. LHCSRs are present and NPQ is active consistently throughout the day, likely due to their slow degradation in vivo. This suggests that in physiologically relevant conditions, Chlamydomonas cells are prepared to immediately activate photoprotection, as is the case in vascular plants. We further reveal that state transitions are fully functional under these conditions and that PsbS is highly expressed throughout the day, suggesting it might have a more impactful role than previously thought.

Original languageEnglish
Pages (from-to)472-479
Number of pages8
JournalPlant physiology
Issue number1
Early online date25 Oct 2019
Publication statusPublished - Jan 2020


1This work was supported by the European Commission (Marie Curie Actions Individual Fellowship 799083 to W.J.N.; consolidator grant 281341 to R.C.), the China Scholarship Council (201606910042 to X.L.), and the Netherlands Organization for Scientific Research (NWO; Vici grant 86510013 to R.C.). 2These authors contributed equally to the article. 3Author for contact: 4Senior author. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors ( is: Roberta Croce ( W.J.N. and R.C. devised the project. W.J.N. and X.L. performed the experiments. All authors analyzed the data. W.J.N. and R.C. wrote the article. [OPEN]Articles can be viewed without a subscription.

FundersFunder number
Netherlands Organization for Scientific Research
Horizon 2020 Framework Programme799083
European Commission281341
Nederlandse Organisatie voor Wetenschappelijk Onderzoek86510013
China Scholarship Council201606910042


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