Dataset Information

CO2 modulation of the rates of photosynthesis and light-dependent O2 consumption in Trichodesmium.

ABSTRACT: As atmospheric CO2 concentrations increase, so too does the dissolved CO2 and HCO3- concentrations in the world's oceans. There are still many uncertainties regarding the biological response of key groups of organisms to these changing conditions, which is crucial for predicting future species distributions, primary productivity rates, and biogeochemical cycling. In this study, we established the relationship between gross photosynthetic O2 evolution and light-dependent O2 consumption in Trichodesmium erythraeum IMS101 acclimated to three targeted pCO2 concentrations (180 µmol mol-1=low-CO2, 380 µmol mol-1=mid-CO2, and 720 µmol mol-1=high-CO2). We found that biomass- (carbon) specific, light-saturated maximum net O2 evolution rates (PnC,max) and acclimated growth rates increased from low- to mid-CO2, but did not differ significantly between mid- and high-CO2. Dark respiration rates were five times higher than required to maintain cellular metabolism, suggesting that respiration provides a substantial proportion of the ATP and reductant for N2 fixation. Oxygen uptake increased linearly with gross O2 evolution across light intensities ranging from darkness to 1100 µmol photons m-2 s-1. The slope of this relationship decreased with increasing CO2, which we attribute to the increased energetic cost of operating the carbon-concentrating mechanism at lower CO2 concentrations. Our results indicate that net photosynthesis and growth of T. erythraeum IMS101 would have been severely CO2 limited at the last glacial maximum, but that the direct effect of future increases of CO2 may only cause marginal increases in growth.

SUBMITTER: Boatman TG

PROVIDER: S-EPMC6322564 | biostudies-other | 2019 Jan

REPOSITORIES: biostudies-other

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CO2 modulation of the rates of photosynthesis and light-dependent O2 consumption in Trichodesmium.

Boatman Tobias G TG Davey Phillip A PA Lawson Tracy T Geider Richard J RJ

Journal of experimental botany 20190101 2

As atmospheric CO2 concentrations increase, so too does the dissolved CO2 and HCO3- concentrations in the world's oceans. There are still many uncertainties regarding the biological response of key groups of organisms to these changing conditions, which is crucial for predicting future species distributions, primary productivity rates, and biogeochemical cycling. In this study, we established the relationship between gross photosynthetic O2 evolution and light-dependent O2 consumption in Trichod ...[more]

PMID: 30380078

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Project description:Background and aimsUnderstanding how climate change influences crop productivity helps in identifying new options to increase crop productivity. Soybean is the most important dicotyledonous seed crop in terms of planting area. Although the impacts of elevated atmospheric [CO2] on soybean physiology, growth and biomass accumulation have been studied extensively, the contribution of different factors to changes in season-long whole crop photosynthetic CO2 uptake [gross primary productivity (GPP)] under elevated [CO2] have not been fully quantified.MethodsA 3-D canopy model combining canopy 3-D architecture, ray tracing and leaf photosynthesis was built to: (1) study the impacts of elevated [CO2] on soybean GPP across a whole growing season; (2) dissect the contribution of different factors to changes in GPP; and (3) determine the extent, if any, of synergism between [CO2] and light on changes in GPP. The model was parameterized from measurements of leaf physiology and canopy architectural parameters at the soybean Free Air CO2 Enrichment (SoyFACE) facility in Champaign, Illinois.Key resultsUsing this model, we showed that both a CO2 fertilization effect and changes in canopy architecture contributed to the large increase in GPP while acclimation in photosynthetic physiological parameters to elevated [CO2] and altered leaf temperature played only a minor role in the changes in GPP. Furthermore, at early developmental stages, elevated [CO2] increased leaf area index which led to increased canopy light absorption and canopy photosynthesis. At later developmental stages, on days with high ambient light levels, the proportion of leaves in a canopy limited by Rubisco carboxylation increased from 12.2 % to 35.6 %, which led to a greater enhancement of elevated [CO2] to GPP.ConclusionsThis study develops a new method to dissect the contribution of different factors to responses of crops under climate change. We showed that there is a synergestic effect of CO2 and light on crop growth under elevated CO2 conditions.

Dataset Information

CO2 modulation of the rates of photosynthesis and light-dependent O2 consumption in Trichodesmium.

Publications

CO2 modulation of the rates of photosynthesis and light-dependent O2 consumption in Trichodesmium.

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