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Pyrenoid-core CO2-evolving machinery is essential for diatom photosynthesis in elevated CO2.
- Source :
-
Plant physiology [Plant Physiol] 2023 Nov 22; Vol. 193 (4), pp. 2298-2305. - Publication Year :
- 2023
-
Abstract
- Marine diatoms are responsible for up to 20% of the annual global primary production by performing photosynthesis in seawater where CO2 availability is limited while HCO3- is abundant. Our previous studies have demonstrated that solute carrier 4 proteins at the plasma membrane of the diatom Phaeodactylum tricornutum facilitate the use of the abundant seawater HCO3-. There has been an unconcluded debate as to whether such HCO3- use capacity may itself supply enough dissolved inorganic carbon (DIC) to saturate the enzyme Rubisco. Here, we show that the θ-type carbonic anhydrase, Ptθ-CA1, a luminal factor of the pyrenoid-penetrating thylakoid membranes, plays an essential role in saturating photosynthesis of P. tricornutum. We isolated and analyzed genome-edited mutants of P. tricornutum defective in Ptθ-CA1. The mutants showed impaired growth in seawater aerated with a broad range of CO2 levels, from atmospheric to 1%. Independently of growth CO2 conditions, the photosynthetic affinity measured as K0.5 for DIC in mutants reached around 2 mm, which is about 10 times higher than K0.5[DIC] of high-CO2-grown wild-type cells that have repressed CO2-concentrating mechanism levels. The results clearly indicate that diatom photosynthesis is not saturated with either seawater-level DIC or even under a highly elevated CO2 environment unless the CO2-evolving machinery is at the core of the pyrenoid.<br />Competing Interests: Conflict of interest statement. The authors have no conflict of interest to declare.<br /> (© American Society of Plant Biologists 2023. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
Details
- Language :
- English
- ISSN :
- 1532-2548
- Volume :
- 193
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Plant physiology
- Publication Type :
- Academic Journal
- Accession number :
- 37625790
- Full Text :
- https://doi.org/10.1093/plphys/kiad475