Fluorescence as a Tool to Understand Changes in Photosynthetic Electron Flow Regulation

Ralph, Peter J.; Wilhelm, Christian; Lavaud, Johann; Jakob, Torsten; Petrou, Katherina; Kranz, Sven A.

doi:10.1007/978-90-481-9268-7_4

Cited by 16 publications

(13 citation statements)

References 117 publications

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“…Similarly, the complete loss of F V / F M by the inhibitor CCCP was expected (Fig. 3a, b), as it dissociates electron transport from ATP synthesis and impedes the establishment of a pH gradient across the thylakoid membrane (Ralph et al 2010). Consequently, CCCP also strongly inhibited 14 C incorporation in +Fe and +DFB cells (Fig.…”

Section: Discussionsupporting

confidence: 55%

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

et al. 2014

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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 Chaetocerossimplex, 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.

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Section: Discussionsupporting

confidence: 55%

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

et al. 2014

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“…These measurements represent (F m ' − F ')/F m ', which is the ratio of maximal fluorescence range to the background minimum fluorescence level, or, in other words, the maximal PSII photochemical efficiency in actinic light. The fluorometer measures light energy that is re-emitted from chlorophyll a (chl a) that is not used for charge separation, heat dissipation or resonance (Cosgrove & Borowitzka 2010, Ralph et al 2010. Field measurements are said to be measured at 'steady state', meaning fluorescence was measured after cells had photoregulated to the ambient light, whereas laboratory experiments measured 'dark-adapted' fluorescence (Huot & Babin 2010).…”

Section: Field Measurementsmentioning

confidence: 99%

Versatile photophysiology of compositionally similar cyanobacterial mat communities inhabiting submerged sinkholes of Lake Huron

Snider¹,

Biddanda²,

Lindback³

et al. 2017

Aquat. Microb. Ecol.

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Recently discovered submerged sinkholes in Lake Huron are high-sulfur, lowoxygen extreme environments for microbial life. In order to understand the relationship between the physical environment, photophysiology and community composition, we measured the physical conditions, photophysiological indices, and genetic diversity at 3 microbial mat sites bathed in high conductivity groundwater under a natural light gradient during 2012 and 2013. A strong seasonal trend prevailed at all sites, characterized by decreased photosynthetic yield (F v '/F m '; 0.25 to 0.40) during the summer (April to August) and increased yield (0.70 to 0.75) during the winter (November to March). Chlorophyll a content varied seasonally in a similar manner to photosynthetic yield. All sites were dominated by > 80% abundance of one cyanobacterial group, most closely related to Phormidium sp. Phycobilins (phycocyanin and phycoerythrin) were consistently higher in concentration than chlorophyll. Photosynthetic yield was statistically indistinguishable between sites, suggesting that these mat communities are able to acclimate across a wide range of photosynthetically active radiation (PAR). Interestingly, these cyanobacteria carried out oxygenic photosynthesis in the presence of in vitro H 2 S, further suggestive of their versatile photophysiologies under variable redox conditions. Collectively, our study provides insight into the adaptive capabilities of cyanobacteria by revealing how they photophysiologically respond to changes in light climate and redox conditions, and are thereby able to inhabit a wide range of physico-chemical environments. Such versatile physiologies may have enabled their ancestors to thrive across a range of habitats on early Earth.

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“…Early efforts to reconcile conventional CO 2 uptake rates with FRRf-derived CO 2 uptake attributed FRRf "overestimates" to use of a constant K C value (i.e., 4 or 5 mol e − (mol C) −1 ) (Kromkamp et al, 2008;Mino et al, 2014), in particular under excess irradiance (Ralph et al, 2010). Subsequent studies demonstrated that miss-matches between CO 2 uptake rates and FRRf were largely due to K C variability, which in turn could be explained (predicted) from co-variability with key environmental factors known to regulate PP, i.e., light, temperature and/or inorganic nutrient availability (Lawrenz et al, 2013;Hughes et al, 2018b;Ryan-Keogh et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Primary Productivity Dynamics in the Summer Arctic Ocean Confirms Broad Regulation of the Electron Requirement for Carbon Fixation by Light-Phytoplankton Community Interaction

et al. 2019

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Zhu et al. Phytoplankton Photophysiology in Arctic Ocean community structure integrates past and immediate environmental histories and hence may be a better broad-scale predictor of K C than specific environmental factors such as temperature and nutrients. We provide a novel algorithm that may enable broad-scale retrieval of CO 2 uptake from FRRf with knowledge of light and phytoplankton community size information.

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Fluorescence as a Tool to Understand Changes in Photosynthetic Electron Flow Regulation

Cited by 16 publications

References 117 publications

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

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

Versatile photophysiology of compositionally similar cyanobacterial mat communities inhabiting submerged sinkholes of Lake Huron

Primary Productivity Dynamics in the Summer Arctic Ocean Confirms Broad Regulation of the Electron Requirement for Carbon Fixation by Light-Phytoplankton Community Interaction

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