A minimal mathematical model of nonphotochemical quenching of chlorophyll fluorescence

Ebenhöh, Oliver; Houwaart, Torsten; Lokstein, Heiko; Schlede, Stephanie; Tirok, Katrin

doi:10.1016/j.biosystems.2010.10.011

Cited by 53 publications

(56 citation statements)

References 23 publications

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“…The model includes all relevant processes involved in the electron transport chain but is deliberately kept as simple as possible. We here focus on the investigation of state transitions in the green alga C. reinhardtii and thus see our work as a continuation of previous theoretical approaches to study NPQ, which addressed in particular the qE component [57,58].…”

Section: Resultsmentioning

confidence: 99%

Short-term acclimation of the photosynthetic electron transfer chain to changing light: a mathematical model

Ebenhöh

Fucile

Finazzi

et al. 2014

Phil. Trans. R. Soc. B

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One contribution of 20 to a Theme Issue 'Changing the light environment: chloroplast signalling and response mechanisms'. Photosynthetic eukaryotes house two photosystems with distinct light absorption spectra. Natural fluctuations in light quality and quantity can lead to unbalanced or excess excitation, compromising photosynthetic efficiency and causing photodamage. Consequently, these organisms have acquired several distinct adaptive mechanisms, collectively referred to as non-photochemical quenching (NPQ) of chlorophyll fluorescence, which modulates the organization and function of the photosynthetic apparatus. The ability to monitor NPQ processes fluorometrically has led to substantial progress in elucidating the underlying molecular mechanisms. However, the relative contribution of distinct NPQ mechanisms to variable light conditions in different photosynthetic eukaryotes remains unclear. Here, we present a mathematical model of the dynamic regulation of eukaryotic photosynthesis using ordinary differential equations. We demonstrate that, for Chlamydomonas, our model recapitulates the basic fluorescence features of short-term light acclimation known as state transitions and discuss how the model can be iteratively refined by comparison with physiological experiments to further our understanding of light acclimation in different species.

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Section: Resultsmentioning

confidence: 99%

Short-term acclimation of the photosynthetic electron transfer chain to changing light: a mathematical model

Ebenhöh

Fucile

Finazzi

et al. 2014

Phil. Trans. R. Soc. B

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“…Although many computational models of PETC in C3 plants have been published in recent years (Riznichenko et al, 2009;Ebenhöh et al, 2011;Zaks et al, 2012;Tikhonov and Vershubskii, 2014;Matuszy nska et al, 2016), they have been predominantly focused on specific mechanisms rather than on the interactions among mechanisms. For example, several models developed to study NPQ (Ebenhöh et al, 2011;Zaks et al, 2012;Matuszy nska et al, 2016) simplify the transport of electrons from PSII to NADPH and do not include any description of the metabolism that consumes ATP and NADPH. Such simplifications prevent the study of the complex interactions that characterize the behavior of the system under natural conditions, such as the effect that changes in Rubisco activity would have on NPQ (Carmo-Silva and Salvucci, 2013;Kaiser et al, 2016).…”

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confidence: 99%

“…One powerful approach is to develop computational models to explore the holistic behavior of the biological network (Kitano, 2002). Although many computational models of PETC in C3 plants have been published in recent years (Riznichenko et al, 2009;Ebenhöh et al, 2011;Zaks et al, 2012;Tikhonov and Vershubskii, 2014;Matuszy nska et al, 2016), they have been predominantly focused on specific mechanisms rather than on the interactions among mechanisms. For example, several models developed to study NPQ (Ebenhöh et al, 2011;Zaks et al, 2012;Matuszy nska et al, 2016) simplify the transport of electrons from PSII to NADPH and do not include any description of the metabolism that consumes ATP and NADPH.…”

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confidence: 99%

In Silico Analysis of the Regulation of the Photosynthetic Electron Transport Chain in C3 Plants

et al. 2017

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ORCID IDs: 0000-0002-6129-4570 (A.M.); 0000-0001-8273-8022 (X.Y); 0000-0002-0607-4508 (J.H.); 0000-0003-4144-6028 (S.M.D.); 0000-0001-6011-7487 (J.M.); 0000-0003-2196-547X (P.C.S.).We present a new simulation model of the reactions in the photosynthetic electron transport chain of C3 species. We show that including recent insights about the regulation of the thylakoid proton motive force, ATP/NADPH balancing mechanisms (cyclic and noncyclic alternative electron transport), and regulation of Rubisco activity leads to emergent behaviors that may affect the operation and regulation of photosynthesis under different dynamic environmental conditions. The model was parameterized with experimental results in the literature, with a focus on Arabidopsis (Arabidopsis thaliana). A dataset was constructed from multiple sources, including measurements of steady-state and dynamic gas exchange, chlorophyll fluorescence, and absorbance spectroscopy under different light intensities and CO 2 , to test predictions of the model under different experimental conditions. Simulations suggested that there are strong interactions between cyclic and noncyclic alternative electron transport and that an excess capacity for alternative electron transport is required to ensure adequate redox state and lumen pH. Furthermore, the model predicted that, under specific conditions, reduction of ferredoxin by plastoquinol is possible after a rapid increase in light intensity. Further analysis also revealed that the relationship between ATP synthesis and proton motive force was highly regulated by the concentrations of ATP, ADP, and inorganic phosphate, and this facilitated an increase in nonphotochemical quenching and proton motive force under conditions where metabolism was limiting, such as low CO 2 , high light intensity, or combined high CO 2 and high light intensity. The model may be used as an in silico platform for future research on the regulation of photosynthetic electron transport.Plants face highly variable environmental conditions, with fluctuations of light intensity, temperature, humidity, and CO 2 that occur over a wide range of time scales, from seconds to seasons. Imbalances between the rate of light capture and CO 2 assimilation can lead to an excess of energy in the system. Under such conditions, photosynthesis faces three main challenges:1. To dissipate the excess of energy that could otherwise result in the production of reactive oxygen species (Foyer et al., 2011); 2. To couple the production and demand of ATP and NADPH in chloroplasts under a fluctuating environment (Noctor and Foyer, 2000); 3. To maintain an adequate redox state (Allen, 2004) of the photosynthetic electron transport chain (PETC).In this study, we use the term regulation to indicate those mechanisms that allow photosynthesis to achieve these goals. These goals must be met simultaneously, and several mechanisms have been identified as contributing (Kramer et al., 2004), including:1. Nonphotochemical quenching (NPQ) of excess energy absorbed by photosynthetic...

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“…The model is based on the dynamic three-state PSU model of Wu and Merchuk (2001) and refined to incorporate the abovementioned acclimation and regulation effects. In addition to growth, the three state model can predict changes in the state of PSII over time as monitored by chlorophyll fluorescence data (Ebenhöh et al, 2011). This model is useful to investigate whether the general assumptions of photosynthetic growth modelling assigned in this study have been reasonable.…”

Section: Introductionmentioning

confidence: 97%

Photosynthesis of microalgae in outdoor mass cultures and modelling its effects on biomass productivity for fuels, feeds and chemicals

Yarnold¹

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Practical applications of microalgae include uses as feedstocks for sustainable fuels, feeds, nutraceuticals, and chemicals; for the treatment of wastewater and industrial flue gas; and for use as recombinant protein expression systems. Improvements in biomass yields are required for commercially viable and sustainable algal technologies, particularly for low value commodities such as biofuels.Although several algae exhibit higher growth rates than terrestrial crops, with theoretical upper limits of 8-10% photon conversion efficiency (PCE), solar-illuminated outdoor microalgal production systems typically have a PCE far below this and even below those achieved under laboratory conditions. The most intractable limiting factor is poor light distribution through the mass culture, where photoinhibitory light at the surface and dark zones deeper in the culture reduce photosynthetic productivity. Moreover, microalgae have evolved a suite of photoacclimation and photoregulation mechanisms to cope with rapid (seconds to minutes) light fluxes in natural environments, yet these processes remain poorly understood in well-mixed photobioreactors.The aim of this thesis study was to combine an experimental and theoretical approach to: 1) investigate and understand the photosynthetic response of algae under mass culture conditions; 2) develop a mathematical model which could accurately predict light-tobiomass productivities under a broad range of design scenarios for outdoor production systems; and 3) identify key biological and design parameters to maximise biomass yields.In the first part of the study, a light-to-biomass model was developed that could be easily applied to rapidly assess biomass yields of different algal strains under a range of design scenarios. This model predicts temporal and spatial irradiance at the reactor surface and through the mass culture with inputs of local solar radiation data, local coordinates, system properties and the optical properties of the culture. Local growth rates are then coupled to local light intensities within the reactor based on a static Haldane growth model derived from empirical growth-irradiance curves. Growth rates are integrated over space and time to compute areal and volumetric productivities.Validation of the model was attempted by conducting batch harvest experiments in a laboratory scale photobioreactor matrix which simulated diurnal light cycles representative of three 'typical' days of solar radiation in Brisbane. The strains used were ii Chlamydomonas reinhardtii and its truncated light-harvesting antenna mutant, tla1, reported to possess improved optical properties. Initially, the model did not satisfactorily predict growth under batch cultivation for the three different incident light conditions, overestimating productivity under low light days and overestimating on high light days.Subsequent adjustment of the model to include photoacclimative changes in the optical properties of the cell and a re-fit of the growth parameter values provided a more accurate m...

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A minimal mathematical model of nonphotochemical quenching of chlorophyll fluorescence

Cited by 53 publications

References 23 publications

Short-term acclimation of the photosynthetic electron transfer chain to changing light: a mathematical model

Short-term acclimation of the photosynthetic electron transfer chain to changing light: a mathematical model

In Silico Analysis of the Regulation of the Photosynthetic Electron Transport Chain in C3 Plants

Photosynthesis of microalgae in outdoor mass cultures and modelling its effects on biomass productivity for fuels, feeds and chemicals

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