Wilson, S., Johnson, M.P. and Ruban, A.V. (2021) ΔpH dominates proton motive force in plant photosynthesis in both low and high light. Plant Physiology, 187 (1). pp. 263-275. ISSN 0032-0889
Abstract
The proton motive force (pmf) across the thylakoid membrane couples photosynthetic electron transport and ATP synthesis. In recent years, the electrochromic carotenoid and chlorophyll absorption band shift (ECS), peaking ∼515 nm, has become a widely used probe to measure pmf in leaves. However, the use of this technique to calculate the parsing of the pmf between the proton gradient (ΔpH) and electric potential (Δψ) components remains controversial. Interpretation of the ECS signal is complicated by overlapping absorption changes associated with violaxanthin de-epoxidation to zeaxanthin (ΔA505) and energy-dependent non-photochemical quenching (qE) (ΔA535). In this study, we used Arabidopsis (Arabidopsis thaliana) plants with altered xanthophyll cycle activity and photosystem II subunit S (PsbS) content to disentangle these overlapping contributions. In plants where overlap between ΔA505, ΔA535 and ECS is diminished, such as npq4 (lacking ΔA535) and npq1npq4 (also lacking ΔA505), the parsing method implies the Δψ contribution is virtually absent and pmf is solely composed of ΔpH. Conversely, in plants where ΔA535 and ECS overlap is enhanced, such as L17 (a PsbS overexpressor) and npq1 (where ΔA535 is blue-shifted to 525 nm) the parsing method implies a dominant contribution of Δψ to the total pmf. These results demonstrate the vast majority of the pmf attributed by the ECS parsing method to Δψ is caused by ΔA505 and ΔA535 overlap, confirming pmf is dominated by ΔpH following the first 60 seconds of continuous illumination under both low and high light conditions. Further implications of these findings for the regulation of photosynthesis are discussed.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © American Society of Plant Biologists 2021. This is an author-produced version of a paper subsequently published in Plant Physiology. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) > Department of Molecular Biology and Biotechnology (Sheffield) |
Funding Information: | Funder Grant number LEVERHULME TRUST (THE) RPG-2019-045 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 29 Jun 2021 15:57 |
Last Modified: | 12 Jun 2022 23:40 |
Status: | Published |
Publisher: | Oxford University Press (OUP) |
Refereed: | Yes |
Identification Number: | 10.1093/plphys/kiab270 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:175725 |