Publication Date:
2024-03-15
Description:
The marine diazotrophic cyanobacterium Trichodesmium responds to elevated atmospheric CO2 partial pressure (pCO2) with higher N2 fixation and growth rates. To unveil the underlying mechanisms, we examined the combined influence of pCO2(150 and 900 µatm) and light (50 and 200 µmol photons m-2 s-1) on TrichodesmiumIMS101. We expand on a complementary study that demonstrated that while elevated pCO2 enhanced N2 fixation and growth, oxygen evolution and carbon fixation increased mainly as a response to high light. Here, we investigated changes in the photosynthetic fluorescence parameters of photosystem II, in ratios of the photosynthetic units (photosystem I:photosystem II), and in the pool sizes of key proteins involved in the fixation of carbon and nitrogen as well as their subsequent assimilation. We show that the combined elevation in pCO2 and light controlled the operation of the CO2-concentrating mechanism and enhanced protein activity without increasing their pool size. Moreover, elevated pCO2 and high light decreased the amounts of several key proteins (NifH, PsbA, and PsaC), while amounts of AtpB and RbcL did not significantly change. Reduced investment in protein biosynthesis, without notably changing photosynthetic fluxes, could free up energy that can be reallocated to increase N2 fixation and growth at elevated pCO2 and light. We suggest that changes in the redox state of the photosynthetic electron transportchain and posttranslational regulation of key proteins mediate the high flexibility in resources and energy allocation in Trichodesmium. This strategy should enableTrichodesmium to flourish in future surface oceans characterized by elevated pCO2, higher temperatures, and high light.
Keywords:
Alkalinity, Gran titration (Gran, 1950); Alkalinity, total; Aragonite saturation state; Bacteria; Bicarbonate ion; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; CF1 subunit of ATP synthase protein; CF1 subunit of ATP synthase protein, standard deviation; Comment; Cyanobacteria; Effective absorbance cross-section of photosystem II; Effective absorbance cross-section of photosystem II, standard deviation; Electron transport rate of photosystem II, per cell; Electron transport rate of photosystem II, standard deviation; EPOCA; EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis; European Project on Ocean Acidification; Experimental treatment; Fluorescence, intrinsic; Fluorescence, intrinsic, standard deviation; Fluorescence, maximum; Fluorescence, maximum, standard deviation; Fluorescence, variable; Fluorescence, variable, standard deviation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); GlnA subunit of Gln synthetase; GlnA subunit of Gln synthetase, standard deviation; Iron protein of nitrogenase; Iron protein of nitrogenase, standard deviation; Laboratory experiment; Laboratory strains; Light; Maximum photochemical quantum yield of photosystem II; Maximum photochemical quantum yield of photosystem II, standard deviation; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Open photosystem II reaction centers; Open photosystem II reaction centers, standard deviation; Other metabolic rates; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Photosynthetic protein, PsbA, standard deviation; Photosynthetic protein, PsbC; Photosynthetic protein, PsbC, standard deviation; Photosynthetic protein PsbA; Photosynthetic protein Rubisco; Photosynthetic protein Rubisco, standard deviation; Phytoplankton; Primary production/Photosynthesis; Radiation, photosynthetically active; Salinity; see reference(s); Single species; Temperature, water; Time in hours; Trichodesmium sp.
Type:
Dataset
Format:
text/tab-separated-values, 608 data points
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