The impact of iron limitation on the physiology of the Antarctic diatom Chaetoceros simplex

Petrou, K; Trimborn, S; Rost, B; Ralph, PJ; Hassler, CS

The impact of iron limitation on the physiology of the Antarctic diatom Chaetoceros simplex

Petrou, K

Trimborn, S Rost, B Ralph, PJ

Hassler, CS

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Publication Type:: Journal Article
Citation:: Marine Biology, 2014, 161 (4), pp. 925 - 937
Issue Date:: 2014-01-01

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Field	Value	Language
dc.contributor.author	Petrou, K https://orcid.org/0000-0002-2703-0694	en_US
dc.contributor.author	Trimborn, S	en_US
dc.contributor.author	Rost, B	en_US
dc.contributor.author	Ralph, PJ https://orcid.org/0000-0002-3103-7346	en_US
dc.contributor.author	Hassler, CS	en_US
dc.date.available	2014-01-13	en_US
dc.date.issued	2014-01-01	en_US
dc.identifier.citation	Marine Biology, 2014, 161 (4), pp. 925 - 937	en_US
dc.identifier.issn	0025-3162	en_US
dc.identifier.uri	http://hdl.handle.net/10453/35861
dc.description.abstract	Iron availability strongly governs the growth of Southern Ocean phytoplankton. To investigate how iron limitation affects photosynthesis as well as the uptake of carbon and iron in the Antarctic diatom Chaetoceros simplex, a combination of chlorophyll a fluorescence measurements and radiotracer incubations in the presence and absence of chemical inhibitors was conducted. Iron limitation in C. simplex led to a decline in growth rates, photochemical efficiency and structural changes in photosystem II (PSII), including a reorganisation of photosynthetic units in PSII and an increase in size of the functional absorption cross section of PSII. Iron-limited cells further exhibited a reduced plastoquinone pool and decreased photosynthetic electron transport rate, while non-photochemical quenching and relative xanthophyll pigment content were strongly increased, suggesting a photoprotective response. Additionally, iron limitation resulted in a strong decline in carbon fixation and thus the particulate organic carbon quotas. Inhibitor studies demonstrated that, independent of the iron supply, carbon fixation was dependent on internal, but not on extracellular carbonic anhydrase activity. Orthovanadate more strongly inhibited iron uptake in iron-limited cells, indicating that P-type ATPase transporters are involved in iron uptake. The stronger reduction in iron uptake by ascorbate in iron-limited cells suggests that the re-oxidation of iron is required before it can be taken up and further supports the presence of a high-affinity iron transport pathway. The measured changes to photosystem architecture and shifts in carbon and iron uptake strategies in C. simplex as a result of iron limitation provide evidence for a complex interaction of these processes to balance the iron requirements for photosynthesis and carbon demand for sustained growth in iron-limited waters. © 2014 The Author(s).	en_US
dc.relation.ispartof	Marine Biology	en_US
dc.relation.isbasedon	10.1007/s00227-014-2392-z	en_US
dc.subject.classification	Marine Biology & Hydrobiology	en_US
dc.title	The impact of iron limitation on the physiology of the Antarctic diatom Chaetoceros simplex	en_US
dc.type	Journal Article
utslib.citation.volume	4	en_US
utslib.citation.volume	161	en_US
utslib.for	060705 Plant Physiology	en_US
utslib.for	060104 Cell Metabolism	en_US
utslib.for	050101 Ecological Impacts of Climate Change	en_US
utslib.for	05 Environmental Sciences	en_US
utslib.for	06 Biological Sciences	en_US
utslib.for	07 Agricultural and Veterinary Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
pubs.organisational-group	/University of Technology Sydney/Strength - C3 - Climate Change Cluster
utslib.copyright.status	open_access
pubs.issue	4	en_US
pubs.publication-status	Published	en_US
pubs.volume	161	en_US

Abstract:

Iron availability strongly governs the growth of Southern Ocean phytoplankton. To investigate how iron limitation affects photosynthesis as well as the uptake of carbon and iron in the Antarctic diatom Chaetoceros simplex, a combination of chlorophyll a fluorescence measurements and radiotracer incubations in the presence and absence of chemical inhibitors was conducted. Iron limitation in C. simplex led to a decline in growth rates, photochemical efficiency and structural changes in photosystem II (PSII), including a reorganisation of photosynthetic units in PSII and an increase in size of the functional absorption cross section of PSII. Iron-limited cells further exhibited a reduced plastoquinone pool and decreased photosynthetic electron transport rate, while non-photochemical quenching and relative xanthophyll pigment content were strongly increased, suggesting a photoprotective response. Additionally, iron limitation resulted in a strong decline in carbon fixation and thus the particulate organic carbon quotas. Inhibitor studies demonstrated that, independent of the iron supply, carbon fixation was dependent on internal, but not on extracellular carbonic anhydrase activity. Orthovanadate more strongly inhibited iron uptake in iron-limited cells, indicating that P-type ATPase transporters are involved in iron uptake. The stronger reduction in iron uptake by ascorbate in iron-limited cells suggests that the re-oxidation of iron is required before it can be taken up and further supports the presence of a high-affinity iron transport pathway. The measured changes to photosystem architecture and shifts in carbon and iron uptake strategies in C. simplex as a result of iron limitation provide evidence for a complex interaction of these processes to balance the iron requirements for photosynthesis and carbon demand for sustained growth in iron-limited waters. © 2014 The Author(s).

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