Publication Date:
2024-03-15
Description:
While intertidal macroalgae are exposed to drastic changes in solar photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) during a diel cycle, and to ocean acidification (OA) associated with increasing CO2 levels, little is known about their photosynthetic performance under the combined influences of these drivers. In this work, we examined the photoprotective strategies controlling electron flow through photosystems II (PSII) and photosystem I (PSI) in response to solar radiation with or without UVR and an elevated CO2 concentration in the intertidal, commercially important, red macroalgae Pyropia (previously Porphyra) yezoensis. By using chlorophyll fluorescence techniques, we found that high levels of PAR alone induced photoinhibition of the inter-photosystem electron transport carriers, as evidenced by the increase of chlorophyll fluorescence in both the J- and I-steps of Kautsky curves. In the presence of UVR, photoinduced inhibition was mainly identified in the O2-evolving complex (OEC) and PSII, as evidenced by a significant increase in the variable fluorescence at the K-step (Fk) of Kautsky curves relative to the amplitude of FJ−Fo (Wk) and a decrease of the maximum quantum yield of PSII (Fv/Fm). Such inhibition appeared to ameliorate the function of downstream electron acceptors, protecting PSI from over-reduction. In turn, the stable PSI activity increased the efficiency of cyclic electron transport (CET) around PSI, dissipating excess energy and supplying ATP for CO2 assimilation. When the algal thalli were grown under increased CO2 and OA conditions, the CET activity became further enhanced, which maintained the OEC stability and thus markedly alleviating the UVR-induced photoinhibition. In conclusion, the well-established coordination between PSII and PSI endows P. yezoensis with a highly efficient photochemical performance in response to UVR, especially under the scenario of future increased CO2 levels and OA.
Keywords:
Activity of cyclic electron transport around Photosystem I; Activity of cyclic electron transport around Photosystem I, standard deviation; Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Benthos; Bicarbonate ion; Bicarbonate ion, standard deviation; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, standard deviation; Coast and continental shelf; Effective quantum yield; Effective quantum yield, standard deviation; EXP; Experiment; Experiment duration; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gaogong_Island_OA; Laboratory experiment; Light; Macroalgae; North Pacific; OA-ICC; Ocean Acidification International Coordination Centre; Oxygen evolving complex activity; Oxygen evolving complex activity, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Photochemical quantum yield; Photochemical quantum yield, standard deviation; Photosystem I donor side activity; Photosystem I donor side activity, standard deviation; Photosystem II acceptor side activity; Photosystem II acceptor side activity, standard deviation; Plantae; Potentiometric; Potentiometric titration; Primary production/Photosynthesis; Pyropia yezoensis; Quantum yield for reduction of Photosystem I acceptor side; Quantum yield for reduction of Photosystem I acceptor side, standard deviation; Quantum yield of electron transport; Quantum yield of electron transport, standard deviation; Registration number of species; Rhodophyta; Salinity; Single species; Species; Temperate; Temperature, water; Temperature, water, standard deviation; Treatment; Type; Uniform resource locator/link to reference
Type:
Dataset
Format:
text/tab-separated-values, 276 data points
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