Plant Growth under Natural Light Conditions Provides Highly Flexible Short-Term Acclimation Properties toward High Light Stress

In the presented study, we describe techniques for glutathione and pigment determination in lichens used in our laboratory. Glutathione and xanthophyll cycle pigments, especially zeaxanthin, are important antioxidants protecting plants against various stresses. In our laboratory, the high light stress in lichens has been intensively studied for several years. We extract glutathione in HCl and determine it by thiol-binding fluorescence label monobromobimane. For pigment determination, homogenized lichen thalli are extracted with pure acetone. According to our results, the total amount of glutathione decreases after a short-term high light exposure, while the amount of zeaxanthin increases.

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Defoliation Significantly Suppressed Plant Growth Under Low Light Conditions in Two Leguminosae Species

Frontiers in Plant Science ◽

10.3389/fpls.2021.777328 ◽

2022 ◽

Vol 12 ◽

Author(s):

Ning Wang ◽

Tianyu Ji ◽

Xiao Liu ◽

Qiang Li ◽

Kulihong Sairebieli ◽

...

Keyword(s):

Plant Growth ◽

Combined Treatment ◽

Chlorophyll Concentration ◽

Light Stress ◽

Early Period ◽

Light Treatment ◽

High Light ◽

Herbivorous Insects ◽

Light Conditions ◽

Low Light

Seedlings in regenerating layer are frequently attacked by herbivorous insects, while the combined effects of defoliation and shading are not fully understood. In the present study, two Leguminosae species (Robinia pseudoacacia and Amorpha fruticosa) were selected to study their responses to combined light and defoliation treatments. In a greenhouse experiment, light treatments (L+, 88% vs L−, 8% full sunlight) and defoliation treatments (CK, without defoliation vs DE, defoliation 50% of the upper crown) were applied at the same time. The seedlings’ physiological and growth traits were determined at 1, 10, 30, and 70 days after the combined treatment. Our results showed that the effects of defoliation on growth and carbon allocation under high light treatments in both species were mainly concentrated in the early stage (days 1–10). R. pseudoacacia can achieve growth recovery within 10 days after defoliation, while A. fruticosa needs 30 days. Seedlings increased SLA and total chlorophyll concentration to improve light capture efficiency under low light treatments in both species, at the expense of reduced leaf thickness and leaf lignin concentration. The negative effects of defoliation treatment on plant growth and non-structural carbohydrates (NSCs) concentration in low light treatment were significantly higher than that in high light treatment after recovery for 70 days in R. pseudoacacia, suggesting sufficient production of carbohydrate would be crucial for seedling growth after defoliation. Plant growth was more sensitive to defoliation and low light stress than photosynthesis, resulting in NSCs accumulating during the early period of treatment. These results illustrated that although seedlings could adjust their resource allocation strategy and carbon dynamics in response to combined defoliation and light treatments, individuals grown in low light conditions will be more suppressed by defoliation. Our results indicate that we should pay more attention to understory seedlings’ regeneration under the pressure of herbivorous insects.

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

Communications Biology ◽

10.1038/s42003-021-01875-y ◽

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.

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

Life ◽

10.3390/life11080812 ◽

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.

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PSII activity and pigment dynamics of Symbiodinium in two Indo-Pacific corals exposed to short-term high-light stress

Marine Biology ◽

10.1007/s00227-012-2113-4 ◽

2012 ◽

Vol 160 (3) ◽

pp. 563-577 ◽

Cited By ~ 9

Author(s):

Wiebke E. Krämer ◽

Verena Schrameyer ◽

Ross Hill ◽

Peter J. Ralph ◽

Kai Bischof

Keyword(s):

Light Stress ◽

High Light ◽

Short Term ◽

High Light Stress ◽

Psii Activity

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Entropy provides an unexpected shield in photosynthesis

Journal of Biological Chemistry ◽

10.1074/jbc.h120.016039 ◽

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.

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

Czech Polar Reports ◽

10.5817/cpr2012-1-5 ◽

2012 ◽

Vol 2 (1) ◽

pp. 42-51 ◽

Cited By ~ 11

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.

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