scholarly journals Entropy provides an unexpected shield in photosynthesis

2020 ◽  
Vol 295 (43) ◽  
pp. 14546-14547
Author(s):  
Lijin Tian
Keyword(s):  
Photosystem Ii ◽  
Thylakoid Membrane ◽  
Vascular Plants ◽  
Light Stress ◽  
High Light ◽  
Light Conditions ◽  
Protective Mechanisms ◽  
High Light Stress ◽  
Energy Quenching

Vascular plants combat the excess photon bombarding of high-light conditions with several protective mechanisms. Despite decades of extensive research, new regulatory mech-anisms for photoprotection may remain unknown. Kim et al. now report that the monomeric disordered form of photosystem II (PSII), which is present in higher abundance in the native thylakoid membrane in response to high light, possesses an energy-quenching capability superior to that of the multimeric ordered phase, suggesting a new shielding strategy against high-light stress by altering the macro-organization of PSII supercomplexes.

scholarly journals Why some stems are red: cauline anthocyanins shield photosystem II against high light stress

2010 ◽  
Vol 61 (10) ◽  
pp. 2707-2717 ◽  
Author(s):  
K. S. Gould ◽  
D. A. Dudle ◽  
H. S. Neufeld
Keyword(s):  
Photosystem Ii ◽  
Light Stress ◽  
High Light ◽  
High Light Stress

scholarly journals Mutations in hik26 and slr1916 lead to high-light stress tolerance in Synechocystis sp. PCC6803

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Katsunori Yoshikawa ◽  
Kenichi Ogawa ◽  
Yoshihiro Toya ◽  
Seiji Akimoto ◽  
Fumio Matsuda ◽  
...  
Keyword(s):  
Stress Tolerance ◽  
Parental Strain ◽  
Energy Flow ◽  
Light Stress ◽  
High Light ◽  
Whole Genome Sequence ◽  
Light Conditions ◽  
Adaptive Laboratory Evolution ◽  
High Light Stress ◽  
Desirable Feature

AbstractIncreased tolerance to light stress in cyanobacteria is a desirable feature for their applications. Here, we obtained a high light tolerant (Tol) strain of Synechocystis sp. PCC6803 through an adaptive laboratory evolution, in which the cells were repeatedly sub-cultured for 52 days under high light stress conditions (7000 to 9000 μmol m−2 s−1). Although the growth of the parental strain almost stopped when exposed to 9000 μmol m−2 s−1, no growth inhibition was observed in the Tol strain. Excitation-energy flow was affected because of photosystem II damage in the parental strain under high light conditions, whereas the damage was alleviated and normal energy flow was maintained in the Tol strain. The transcriptome data indicated an increase in isiA expression in the Tol strain under high light conditions. Whole genome sequence analysis and reverse engineering revealed two mutations in hik26 and slr1916 involved in high light stress tolerance in the Tol strain.

scholarly journals Color-Specific Recovery to Extreme High-Light Stress in Plants

Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 812
Author(s):  
Débora Parrine ◽  
Todd M. Greco ◽  
Bilal Muhammad ◽  
Bo-Sen Wu ◽  
Xin Zhao ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Stress ◽  
Red Light ◽  
Light Treatment ◽  
High Light ◽  
Mrna Levels ◽  
Light Conditions ◽  
High Light Stress ◽  
General Response ◽  
The Impact

Plants pigments, such as chlorophyll and carotenoids, absorb light within specific wavelength ranges, impacting their response to environmental light changes. Although the color-specific response of plants to natural levels of light is well described, extreme high-light stress is still being discussed as a general response, without considering the impact of wavelengths in particular response processes. In this study, we explored how the plant proteome coordinated the response and recovery to extreme light conditions (21,000 µmol m−2 s−1) under different wavelengths. Changes at the protein and mRNA levels were measured, together with the photosynthetic parameters of plants under extreme high-light conditions. The changes in abundance of four proteins involved in photoinhibition, and in the biosynthesis/assembly of PSII (PsbS, PsbH, PsbR, and Psb28) in both light treatments were measured. The blue-light treatment presented a three-fold higher non-photochemical quenching and did not change the level of the oxygen-evolving complex (OEC) or the photosystem II (PSII) complex components when compared to the control, but significantly increased psbS transcripts. The red-light treatment caused a higher abundance of PSII and OEC proteins but kept the level of psbS transcripts the same as the control. Interestingly, the blue light stimulated a more efficient energy dissipation mechanism when compared to the red light. In addition, extreme high-light stress mechanisms activated by blue light involve the role of OEC through increasing PsbS transcript levels. In the proteomics spatial analysis, we report disparate activation of multiple stress pathways under three differently damaged zones as the enriched function of light stress only found in the medium-damaged zone of the red LED treatment. The results indicate that the impact of extreme high-light stress on the proteomic level is wavelength-dependent.

scholarly journals ACCLIMATION OF PHOTOSYNTHESIS TO THE ENVIRONMENT 1 regulates Photosystem II Supercomplex dynamics in response to light in Chlamydomonas reinhardtii

2020 ◽  
Author(s):  
Marie Chazaux ◽  
Stefano Caffarri ◽  
Juliane Da Graça ◽  
Stephan Cuiné ◽  
Magali Floriani ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Chlamydomonas Reinhardtii ◽  
Light Stress ◽  
High Light ◽  
Light Acclimation ◽  
Light Conditions ◽  
Core Complex ◽  
Photosynthetic Organisms ◽  
Thylakoid Protein ◽  
Thylakoid Stacking

AbstractPhotosynthetic organisms require acclimation mechanisms to regulate photosynthesis in response to light conditions. Here, two mutant alleles of ACCLIMATION OF PHOTOSYNTHESIS TO THE ENVIRONMENT 1 (ape1) have been characterized in Chlamydomonas reinhardtii. The ape1 mutants are photosensitive and show PSII photoinhibition during high light acclimation or under high light stress. The ape1 mutants retain more PSII super-complexes and have changes to thylakoid stacking relative to control strains during photosynthetic growth at different light intensities. The APE1 protein is found in all oxygenic phototrophs and encodes a 25 kDa thylakoid protein that interacts with the Photosystem II core complex as monomers, dimers and supercomplexes. We propose a model where APE1 bound to PSII supercomplexes releases core complexes and promotes PSII heterogeneity influencing the stacking of Chlamydomonas thylakoids. APE1 is a regulator in light acclimation and its function is to reduce over-excitation of PSII centres and avoid PSII photoinhibition to increase the resilience of photosynthesis to high light.

scholarly journals Photoinhibition of photosynthesis in Antarctic lichen Usnea antarctica. I. Light intensity- and light duration-dependent changes in functioning of photosystem II

2012 ◽  
Vol 2 (1) ◽  
pp. 42-51 ◽  
Author(s):  
Miloš Barták ◽  
Josef Hájek ◽  
Petra Očenášová
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Light Stress ◽  
Term Treatment ◽  
High Light ◽  
Short Term ◽  
High Light Stress ◽  
Long Term Treatment ◽  
James Ross Island

The paper deals with the differences in sensitivity of Antarctic lichen to photoinhibition. Thalli of Usnea antarctica were collected at the James Ross Island, Antarctica (57°52´57´´W, 63°48´02´´S) and transferred in dry state to the Czech Republic. After rewetting in a laboratory, they were exposed to 2 high light treatments: short-term (30 min), and long-term (6 h). In short-term treatment, the sample were exposed to 1000 and 2000 µmol m-2 s-1 of photosynthetically active radiation (PAR). In long-term experiment, PAR of 300, 600, and 1000 µmol m-2 s-1 were used. Photosynthetic efficiency of U. antarctica thalli was monitored by chlorophyll fluorescence parameters, potential (FV/FM) and actual (FPSII) quantum yield of photochemical processes in photosystem II in particular. In short-term treatments, the F0, FV and FM signals, as well as the values of FV/FM, and FPSII showed light-induced decrease, however substantial recovery after consequent 30 min. in dark. Longer exposition (60 min) to high light led to more pronounced decrease in chlorophyll fluorescence than after 30 min treatment, however dark recovery was faster in the thalli treated before for longer time (60 min). Long-term treatment by high light caused gradual decrease in FV/FM and FPSII with the time of exposition. The extent of the decrease was found light dose-dependent. The time course was biphasic for FV/FM but not for FPSII. The study showed that wet thalli of Usnea antarctica had high capacity of photoprotective mechanisms to cope well either with short- or long-term high light stress. This might be of particular importance in the field at the James Ross Island, particularly at the begining of growing season when melting water is available and, simultaneously, high light stress may happen on fully sunny days.

scholarly journals Identification of hydroxy-plastochromanol in Arabidopsis leaves.

2010 ◽  
Vol 57 (1) ◽  
Author(s):  
Renata Szymańska ◽  
Jerzy Kruk
Keyword(s):  
Photosystem Ii ◽  
Singlet Oxygen ◽  
Light Stress ◽  
High Light ◽  
Low Light ◽  
High Light Stress ◽  
First Time

In the present study we have identified hydroxy-plastochromanol in plants for the first time. This compound was found both in low light and high light-grown Arabidopsis plants, however, under high light stress its level was considerably increased. Hydroxy-plastochromanol accumulated also during ageing of leaves of low light-grown plants, similarly as in the case of other prenyllipids. Our results indicate that hydroxy-plastochromanol found in leaves is probably formed as a result of plastochromanol oxidation by singlet oxygen generated in photosystem II during photosynthesis. These data also support the hypothesis that plastochromanol is an efficient antioxidant in vivo, similarly as tocopherols and plastoquinol.

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