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.

Is the in vivo Photosystem I Function Resistant to Photoinhibition? An Answer from Photoacoustic and Far-Red Absorbance Measurements in Intact Leaves

1991 ◽  
Vol 46 (11-12) ◽  
pp. 1038-1044 ◽  
Author(s):  
Michel Havaux ◽  
Murielle Eyletters
Keyword(s):  
Light Stress ◽  
Red Light ◽  
Light Treatment ◽  
High Light ◽  
Saturation Curve ◽  
Strong Light ◽  
Ps Ii ◽  
Fluorescence Measurements ◽  
Ps I

Abstract Preillumination of intact pea leaves with a strong blue-green light of 400 W m-2 markedly inhibited both photoacoustically monitored O2-evolution activity and PS II photochemistry as estimated from chlorophyll fluorescence measurements. The aim of the present work was to examine, with the help of the photoacoustic technique, whether this high-light treatment deteriorated the in vivo PS I function too. High-frequency photoacoustic measurements indicated that photochemical conversion of far-red light energy in PS I was preserved (and even transiently stimulated) whereas photochemical energy storage monitored in light exciting both PS I and PS II was markedly diminished. Low-frequency photoacoustic measurements of the Emerson enhancement showed a spectacular change in the PS II/PS I activity balance in favor of PS I. It was also observed that the linear portion of the saturation curve of the far-red light effect in the Emerson enhancement was not changed by the light treatment. Those results lead to the conclusion that, in contrast to PS II, the in vivo PS I photofunctioning was resistant to strong light stress, thus confirming previous suggestions derived from in vitro studies. Estimation of the redox state of the PS I reaction center by leaf absorbance measurements at ca. 820 nm suggested that, under steady illumination, a considerably larger fraction of PS I centers were in the closed state in high-light pretreated leaves as compared to control leaves, presumably allowing passive adjustment of the macroscopic quantum yield of PS I photochemis­ try to the strongly reduced photochemical efficiency of photoinhibited PS II.

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

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.

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 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 Enzymes degraded under high light maintain proteostasis by transcriptional regulation in Arabidopsis

2021 ◽  
Author(s):  
Lei Li ◽  
Owen Duncan ◽  
Diep R Ganguly ◽  
Chun Pong Lee ◽  
Peter A Crisp ◽  
...  
Keyword(s):  
Protein Degradation ◽  
Light Stress ◽  
High Light ◽  
Coupled Analysis ◽  
Protein Abundance ◽  
Mrna Levels ◽  
Transcriptional Responses ◽  
High Light Stress ◽  
Degradation Rates

Photo-inhibitory high light stress in Arabidopsis leads to increases in markers of protein degradation and transcriptional upregulation of proteases and proteolytic machinery, but proteostasis is largely maintained. We find significant increases in the in vivo degradation rate for specific molecular chaperones, nitrate reductase, glyceraldehyde-3 phosphate dehydrogenase, and phosphoglycerate kinase and other plastid, mitochondrial, peroxisomal, and cytosolic enzymes involved in redox shuttles. Coupled analysis of protein degradation rates, mRNA levels, and protein abundance reveal that 57% of the nuclear-encoded enzymes with higher degradation rates also had high light-induced transcriptional responses to maintain proteostasis. In contrast, plastid-encoded proteins with enhanced degradation rates showed decreased transcript abundances and must maintain protein abundance by other processes. This analysis reveals a light-induced transcriptional program for nuclear-encoded genes, beyond the regulation of PSII D1 subunit and the function of PSII, to replace key protein degradation targets in plants and ensure proteostasis under high light stress.  

scholarly journals Single Wavelengths of LED Light Supplement Promote the Biosynthesis of Major Cyclic Monoterpenes in Japanese Mint

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1420
Author(s):  
Takahiro Ueda ◽  
Miki Murata ◽  
Ken Yokawa
Keyword(s):  
Blue Light ◽  
Solid Phase ◽  
Glandular Trichomes ◽  
Red Light ◽  
Glandular Trichome ◽  
Pulse Amplitude ◽  
Light Treatment ◽  
Led Light ◽  
Trichome Formation ◽  
Japanese Mint

Environmental light conditions influence the biosynthesis of monoterpenes in the mint plant. Cyclic terpenes, such as menthol, menthone, pulegone, and menthofuran, are major odor components synthesized in mint leaves. However, it is unclear how light for cultivation affects the contents of these compounds. Artificial lighting using light-emitting diodes (LEDs) for plant cultivation has the advantage of preferential wavelength control. Here, we monitored monoterpene contents in hydroponically cultivated Japanese mint leaves under blue, red, or far-red wavelengths of LED light supplements. Volatile cyclic monoterpenes, pulegone, menthone, menthol, and menthofuran were quantified using the head-space solid phase microextraction method. As a result, all light wavelengths promoted the biosynthesis of the compounds. Remarkably, two weeks of blue-light supplement increased all compounds: pulegone (362% increase compared to the control), menthofuran (285%), menthone (223%), and menthol (389%). Red light slightly promoted pulegone (256%), menthofuran (178%), and menthol (197%). Interestingly, the accumulation of menthone (229%) or menthofuran (339%) was observed with far-red light treatment. The quantification of glandular trichomes density revealed that no increase under light supplement was confirmed. Blue light treatment even suppressed the glandular trichome formation. No promotion of photosynthesis was observed by pulse-amplitude-modulation (PAM) fluorometry. The present result indicates that light supplements directly promoted the biosynthetic pathways of cyclic monoterpenes.

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