The Enhancement of Photosynthesis by Fluctuating Light

Iluz, David; Alexandrovich, Irit; Dubinsky, Zvy

doi:10.5772/31040

Cited by 19 publications

(17 citation statements)

References 57 publications

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“…We have tested the hypothesis that FL with appropriately balanced intensity, frequency, and flash-todark ratio, induces only a limited de-epoxidation of Vio, so that upregulation of the VC and, hence, NPQ induction occurs at a slower rate and to a lower extent in comparison with CL of the same time-integrated PAR dose. In addition, our data confirmed that the VC is fully functional under FL of high-incident intensity (Iluz et al, 2012) in the chlorophyte D. salina.…”

Section: Discussionsupporting

confidence: 79%

“…It is known that the effect of FL depends on the duty-cycle, i.e. on the ratio of the light energy delivered by a single flash and the dark time available for its utilization (Park & Lee, 2001;Yoshimoto et al, 2005;Kliphuis et al, 2010;Iluz et al, 2012). Indeed, judging from the oxygen evolution-based light curves, this was the case under our experimental conditions, e.g.…”

Section: Discussionmentioning

confidence: 60%

“…The scattering and attenuation of light penetrating the water surface, as well as the lens-like light-focusing properties of surface waves, form (in natural water bodies as well as in artificial cultivation systems) fluctuating illumination domains, with irradiances ranging from supersaturating to complete darkness (Iluz et al, 2012). Since the VC operates on a timescale of seconds to seasons (Demmig-Adams et al, 2012), it is crucial to microalgae dwelling in habitats with abrupt fluctuations of irradiance for the establishment of an optimal balance of light harvesting and photoprotection (Lohr & Wilhelm, 1999;Demmig-Adams & Adams, 2006;Jahns & Holzwarth, 2012;Lunch et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Flashing light enhancement of photosynthesis and growth occurs when photochemistry and photoprotection are balanced inDunaliella salina

Abu‐Ghosh

Fixler

Dubinsky

et al. 2015

European Journal of Phycology

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Photosynthesis and growth in Dunaliella salina were significantly (P ≤ 0.01) enhanced under flashing light with a light-dark cycle tailored for the minimal activation of the violaxanthin cycle (VC), in comparison with cultures grown under constant illumination of the same time-integrated photon dose. The experiments were performed without using inhibitors or any other experimental conditions other than light. The flashing light (FL) was optimally balanced for the growth and photosynthesis of D. salina, which was characterized by a decreased VC de-epoxidation rate. The high-light induction of non-photochemical quenching (NPQ) was significantly slower in the FL-acclimated cells compared with those acclimated to continuous illumination. The comparative investigation of the cell ultrastructure revealed distinct effects of high-light stress in cultures grown under continuous light; this was not the case under FL. We conclude that a slower activation of the VC takes place under balanced flashing light, when each flash is followed by a dark period long enough for utilization of the photons absorbed during the flash at a given irradiance. The activation kinetics of the VC and, hence, the induction of NPQ seem to play an important role in the enhancement of the photosynthesis observed in D. salina grown under flashing light. Potential use of these parameters for optimization of FL for microalgal cultivation is discussed.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

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Flashing light enhancement of photosynthesis and growth occurs when photochemistry and photoprotection are balanced inDunaliella salina

Abu‐Ghosh

Fixler

Dubinsky

et al. 2015

European Journal of Phycology

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“…In order to maintain balanced light absorption and energy utilization under HL conditions, photosynthetic organisms have developed photoprotective mechanisms and efficient electron sinks. Particularly in aquatic environments, photosynthetic microorganisms experience drastic fluctuations in light intensity due to the lens effect of waves, shading caused by clouds and turbulences (Iluz et al ., ). Consequently, the photosynthetic apparatus of aquatic phototrophs requires rapid fine‐tuning.…”

Section: Discussionmentioning

confidence: 97%

Hunting the main player enabling Chlamydomonas reinhardtii growth under fluctuating light

et al. 2018

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SUMMARYPhotosynthetic organisms have evolved numerous photoprotective mechanisms and alternative electron sinks/pathways to fine-tune the photosynthetic apparatus under dynamic environmental conditions, such as varying carbon supply or fluctuations in light intensity. In cyanobacteria flavodiiron proteins (FDPs) protect the photosynthetic apparatus from photodamage under fluctuating light (FL). In Arabidopsis thaliana, which does not possess FDPs, the PGR5-related pathway enables FL photoprotection. The direct comparison of the pgr5, pgrl1 and flv knockout mutants of Chlamydomonas reinhardtii grown under ambient air demonstrates that all three proteins contribute to the survival of cells under FL, but to varying extents. The FDPs are crucial in providing a rapid electron sink, with flv mutant lines unable to survive even mild FL conditions. In contrast, the PGRL1 and PGR5-related pathways operate over relatively slower and longer timescales. Whilst deletion of PGR5 inhibits growth under mild FL, the pgrl1 mutant line is only impacted under severe FL conditions. This suggests distinct roles, yet a close relationship, between the function of PGR5, PGRL1 and FDP proteins in photoprotection.

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“…Furthermore, short term photoprotective mechanisms such as the xanthophyll cycle might intensify efficiency improvements from flashing light. Last, extended exposure to higher light intensities for lower cycle frequencies can lead to increased thermal dissipation rates and thus lower the photosynthetic efficiency (Casper–Lindley and Bjrkman, ; Iluz et al, ). Therefore, a deeper analysis of the photosynthetic yield and non photochemical quenching would be necessary to conclusively identify the physiological mechanism behind the observed increase in growth rate at lowest frequencies.…”

Section: Discussionmentioning

confidence: 99%

Long‐term adaptive response to high‐frequency light signals in the unicellular photosynthetic eukaryote Dunaliella salina

Combe

Hartmann

Rabouille

et al. 2015

Biotech & Bioengineering

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Productivity of microalgal cultivation processes is tightly related to photosynthetic efficiency, and therefore to light availability at the cell scale. In an agitated, highly turbid suspension,the light signal received by a single phytoplankton cell moving in a dense culture is a succession of flashes. The growth characteristics of microalgae under such dynamic light conditions are thus fundamental information to understand nonlinear properties of the photosynthetic process and to improve cultivation process design and operation. Studies of the long term consequences of dynamic illumination regime on photosynthesis require a very specific experimental set-up where fast varying signals are applied on the long term. In order to investigate the growth response of the unicellular photosynthetic eukaryote Dunaliella salina (Chlorophyceae) to intermittent light exposure, different light regimes using LEDs with the same average total light dose were applied in continuous cultures. Flashing light with different durations of light flashes (△t of 30 s, 15 s, 2 s and 0.1 s) followed by dark periods of variable length (0.67 ≤ L:D ≤ 2) yielding flash frequencies in the range 0.017-5 Hz, were compared to continuous illumination. Specific growth rate, photosynthetic pigments, lipid productivity and elemental composition were measured on two duplicates for each irradiance condition. The different treatments of intermittent light led to specific growth rates ranging from 0.25 to 0.93 day(-1) . While photosynthetic efficiency was enhanced with increased flash frequency, no significant differences were observed in the particular carbon and chlorophyll content. Pigment analysis showed that within this range of flash frequency, cells progressively photoacclimated to the average light intensity.

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The Enhancement of Photosynthesis by Fluctuating Light

Cited by 19 publications

References 57 publications

Flashing light enhancement of photosynthesis and growth occurs when photochemistry and photoprotection are balanced inDunaliella salina

Flashing light enhancement of photosynthesis and growth occurs when photochemistry and photoprotection are balanced inDunaliella salina

Hunting the main player enabling Chlamydomonas reinhardtii growth under fluctuating light

Long‐term adaptive response to high‐frequency light signals in the unicellular photosynthetic eukaryote Dunaliella salina

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