Investigation on absorption cross-section of photosynthetic pigment molecules based on a mechanistic model of the photosynthetic electron flow-light response in C3, C4 species and cyanobacteria grown under various conditions

Ye, Zi-Piao; Stirbet, Alexandrina; An, Ting; Robakowski, Piotr; Kang, Hua-Jing; Yang, Xiao-Long; Wang, Fu-Biao

doi:10.3389/fpls.2023.1234462

Cited by 3 publications

(2 citation statements)

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“…Chlorophyll a (Chl a ) was measured using a 4.8-mL sample. The Phytoplankton Analyzer (Phyto-PAM, Walz Co., Erlangen, Germany) was utilized for the assessment of Microcystis photosynthetic activity ( Ye et al., 2023 ). The Fv/Fm parameter represents the potential maximum conversion efficiency of Microcystis photosystem II, as it is overwhelmingly dominant ( Wang et al., 2018 ).…”

Section: Methodsmentioning

confidence: 99%

Effect of extracellular polymeric substances on the colony size and morphological changes of Microcystis

Pan,

Yang,

et al. 2024

Front. Plant Sci.

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Surface blooms of colony-forming Microcystis are increasingly occurring in aquatic ecosystems on a global scale. Recent studies have found that the Microcystis colonial morphology is a crucial factor in the occurrence, persistence, and dominance of Microcystis blooms, yet the mechanism driving its morphological dynamics has remained unknown. This study conducted a laboratory experiment to test the effect of extracellular polymeric substances on the morphological dynamics of Microcystis. Ultrasound was used to disaggregate colonies, isolating the cells and of the Microcystis suspension. The single cells were then re-cultured under three homologous EPS concentrations: group CK, group Low, and group High. The size, morphology, and EPS [including tightly bound EPS (TB-EPS), loosely bound EPS (LB-EPS), bound polysaccharides (B-polysaccharides), and bound proteins (B-proteins)] changes of colonies were closely monitored over a period of 2 months. It was observed that colonies were rapidly formed in group CK, with median colony size (D50) reaching 183 µm on day 12. The proportion of colonies with a size of 150–500 µm increased from 1% to more than 50%. Colony formation was also observed in both groups Low and High, but their D50 increased at a slower rate and remained around 130 µm after day 17. Colonies with a size of 50–150 µm account for more than 50%. Groups CK and Low successively recovered the initial Microcystis morphology, which is a ring structure formed of several small colonies with a D50 of 130 µm. During the recovery of the colony morphology, the EPS per cell increased and then decreased, with TB-EPS and B-polysaccharides constituting the primary components. The results suggest that colony formation transitioned from adhesion driven to being division driven over time. It is suggested that the homologous EPS released into the ambient environment due to the disaggregation of the colony is a chemical cue that can affect the formation of a colony. This plays an important but largely ignored role in the dynamics of Microcystis and surface blooms.

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Section: Methodsmentioning

confidence: 99%

Effect of extracellular polymeric substances on the colony size and morphological changes of Microcystis

Pan,

Yang,

et al. 2024

Front. Plant Sci.

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“…of pigment absorption spectra taken from Taniguchi and Lindsey ( 2018)). The optical/absorption cross-section of such pigments is of the order 𝝈 = 10 −21 − 10 −20 m 2 (Ye et al, 2023). 4.…”

Section: A Coarse-grained Model Of a Generalized Photosynthetic Anten...mentioning

confidence: 99%

Optimizing photosynthetic light-harvesting under stars: Generalized thermodynamic models

Chitnavis,

Gray,

Rousouli

et al. 2024

Preprint

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Since the law of physics and chemistry are universal, we must be able to use them to determine the feasibility and potential characteristics of photosynthetic life on exoplanets. Photosynthesis is the cornerstone of Earth’s complex biosphere and creates bio-signatures pivotal in the search for life beyond Earth. However, stars of lower temperature (𝑻𝒔) diminish the intersection between the irradiance at an exoplanet's surface and the wavelengths of light (400 nm ≤ 𝝀 < 700 nm) required for oxygenic photosynthesis, which includes Earth’s plants and cyanobacteria. This does not automatically preclude photosynthesis around such stars, since Earth's photosynthetic organisms have developed highly-specialized light-harvesting structures, known as antennae, to overcome extremely light-limiting conditions. Here, we construct a generalized thermodynamic model of a photosynthetic antenna and evaluate photosynthetic performance across various stellar spectra. We demonstrate that the light-harvesting process, entailing the capture of light across a broad area and channeling it to a small reaction centre, encounters an intrinsic entropic barrier that constrains its efficiency. Through structural and energetic optimizations of our model, we uncover strategies to alleviate the entropic barrier, akin to those seemingly adopted during the evolution of cyanobacteria. We propose that a cyanobacterial-like antenna is thermodynamically optimized even for the coolest M-dwarf stars (𝑻𝒔 ∼ 2300 K) while a plant-like antenna would face severe entropic constraints. By incorporating thermodynamics into biology, our models help linearize the search for photosynthesis based on the stellar spectra an exoplanet receives.

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Optimizing photosynthetic light-harvesting under stars: simple and general antenna models

Chitnavis,

Gray,

Rousouli

et al. 2024

Photosynth Res

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In the next 10–20 years, several observatories will aim to detect the signatures of oxygenic photosynthesis on exoplanets, though targets must be carefully selected. Most known potentially habitable exo-planets orbit cool M-dwarf stars, which have limited emission in the photosynthetically active region of the spectrum (PAR, $$400< \lambda < 700$$ 400 < λ < 700 nm) used by Earth’s oxygenic photoautotrophs. Still, recent experiments have shown that model cyanobacteria, algae, and non-vascular plants grow comfortably under simulated M-dwarf light, though vascular plants struggle. Here, we hypothesize that this is partly due to the different ways they harvest light, reflecting some general rule that determines how photosynthetic antenna structures may evolve under different stars. We construct a simple thermodynamic model of an oxygenic antenna-reaction centre supercomplex and determine the optimum structure, size and absorption spectrum under light from several star types. For the hotter G (e.g. the Sun) and K-stars, a small modular antenna is optimal and qualitatively resembles the PSII-LHCII supercomplex of higher plants. For the cooler M-dwarfs, a very large antenna with a steep ’energy funnel’ is required, resembling the cyanobacterial phycobilisome. For the coolest M-dwarfs an upper limit is reached, where increasing antenna size further is subject to steep diminishing returns in photosynthetic output. We conclude that G- and K-stars could support a range of niches for oxygenic photo-autotrophs, including high-light adapted canopy vegetation that may generate detectable bio-signatures. M-dwarfs may only be able to support low light-adapted organisms that have to invest considerable resources in maintaining a large antenna. This may negatively impact global coverage and therefore detectability.

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Investigation on absorption cross-section of photosynthetic pigment molecules based on a mechanistic model of the photosynthetic electron flow-light response in C3, C4 species and cyanobacteria grown under various conditions

Cited by 3 publications

References 50 publications

Effect of extracellular polymeric substances on the colony size and morphological changes of Microcystis

Effect of extracellular polymeric substances on the colony size and morphological changes of Microcystis

Optimizing photosynthetic light-harvesting under stars: Generalized thermodynamic models

Optimizing photosynthetic light-harvesting under stars: simple and general antenna models

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