scholarly journals Blue/green light-responsive cyanobacteriochromes are cell shade sensors in red-light replete niches

2019 ◽  
Author(s):  
Gen Enomoto ◽  
Masahiko Ikeuchi
Keyword(s):  
Cell Density ◽  
Blue Light ◽  
Hot Springs ◽  
Incident Light ◽  
Natural Habitat ◽  
Red Light ◽  
Green Light ◽  
Light Response ◽  
Cell Aggregation ◽  
Cell Position

SummaryPhotoautotrophic cyanobacteria have developed sophisticated light response systems to capture and utilize the energy and information of incident light [1]. Cyanobacteria-specific photoreceptors cyanobacteriochromes (CBCRs) are distantly related to more widespread phytochromes. CBCRs show the most diverse spectral properties among the naturally occurring photoreceptors, typified by a unique and prevailing blue/green light-absorbing variant [2–6]. However, where the CBCR-mediated ‘colorful’ signaling systems function in nature has been elusive. We previously reported that the three CBCRs SesA/B/C synthesize/degrade a bacterial second messenger cyclic diguanylate (c-di-GMP) in response to blue/green light [6–8]. The cooperative action of SesA/B/C enables blue light-ON and green light-OFF regulation of the c-di-GMP-dependent cell aggregation of the thermophilic cyanobacterium Thermosynechococcus vulcanus [8, 9]. Here, we report that SesA/B/C can serve as a physiological sensor of cell density. Because cyanobacterial cells show lower transmittance of blue light than green light, higher cell density gives more green light-enriched irradiance to cells. The cell density-dependent suppression of cell aggregation under blue/green-mixed light and white light conditions support this idea. Such a sensing mechanism may provide information about the cell position in cyanobacterial mats in hot springs, the natural habitat of Thermosynechococcus. This cell position-dependent SesA/B/C-mediated regulation of cellular sessility (aggregation) might be ecophysiologically essential for the reorganization and growth of phototrophic mats. We also report that the green light-induced dispersion of cell aggregates requires red light-driven photosynthesis. Blue/green CBCRs might work as shade detectors in a different niche than red/far-red phytochromes, which may be why CBCRs have evolved in cyanobacteria.

scholarly journals Photosynthetic Physiology of Blue, Green, and Red Light: Light Intensity Effects and Underlying Mechanisms

2021 ◽  
Vol 12 ◽  
Author(s):  
Jun Liu ◽  
Marc W. van Iersel
Keyword(s):  
Blue Light ◽  
Interactive Effect ◽  
Red Light ◽  
Green Light ◽  
Photosynthetic Photon Flux Density ◽  
Interactive Effects ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Light Spectrum ◽  
Response Curves

Red and blue light are traditionally believed to have a higher quantum yield of CO2 assimilation (QY, moles of CO2 assimilated per mole of photons) than green light, because green light is absorbed less efficiently. However, because of its lower absorptance, green light can penetrate deeper and excite chlorophyll deeper in leaves. We hypothesized that, at high photosynthetic photon flux density (PPFD), green light may achieve higher QY and net CO2 assimilation rate (An) than red or blue light, because of its more uniform absorption throughtout leaves. To test the interactive effects of PPFD and light spectrum on photosynthesis, we measured leaf An of “Green Tower” lettuce (Lactuca sativa) under red, blue, and green light, and combinations of those at PPFDs from 30 to 1,300 μmol⋅m–2⋅s–1. The electron transport rates (J) and the maximum Rubisco carboxylation rate (Vc,max) at low (200 μmol⋅m–2⋅s–1) and high PPFD (1,000 μmol⋅m–2⋅s–1) were estimated from photosynthetic CO2 response curves. Both QYm,inc (maximum QY on incident PPFD basis) and J at low PPFD were higher under red light than under blue and green light. Factoring in light absorption, QYm,abs (the maximum QY on absorbed PPFD basis) under green and red light were both higher than under blue light, indicating that the low QYm,inc under green light was due to lower absorptance, while absorbed blue photons were used inherently least efficiently. At high PPFD, the QYinc [gross CO2 assimilation (Ag)/incident PPFD] and J under red and green light were similar, and higher than under blue light, confirming our hypothesis. Vc,max may not limit photosynthesis at a PPFD of 200 μmol m–2 s–1 and was largely unaffected by light spectrum at 1,000 μmol⋅m–2⋅s–1. Ag and J under different spectra were positively correlated, suggesting that the interactive effect between light spectrum and PPFD on photosynthesis was due to effects on J. No interaction between the three colors of light was detected. In summary, at low PPFD, green light had the lowest photosynthetic efficiency because of its low absorptance. Contrary, at high PPFD, QYinc under green light was among the highest, likely resulting from more uniform distribution of green light in leaves.

scholarly journals Efficient Photocatalytic CO2 Reduction with MIL-100(Fe)-CsPbBr3 Composites

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1352
Author(s):  
Ruolin Cheng ◽  
Elke Debroye ◽  
Johan Hofkens ◽  
Maarten B. J. Roeffaers
Keyword(s):  
Performance Optimization ◽  
Photocatalytic Performance ◽  
Red Light ◽  
Green Light ◽  
Co2 Reduction ◽  
Light Response ◽  
High Specific Surface Area ◽  
Composite Photocatalysts ◽  
Halide Perovskites ◽  
Carrier Separation

Bromide-based metal halide perovskites (MHPs) are promising photocatalysts with strong blue-green light absorption. Composite photocatalysts of MHPs with MIL-100(Fe), as a powerful photocatalyst itself, have been investigated to extend the responsiveness towards red light. The composites, with a high specific surface area, display an enhanced solar light response, and the improved charge carrier separation in the heterojunctions is employed to maximize the photocatalytic performance. Optimization of the relative composition, with the formation of a dual-phase CsPbBr3 to CsPb2Br5 perovskite composite, shows an excellent photocatalytic performance with 20.4 μmol CO produced per gram of photocatalyst during one hour of visible light irradiation.

scholarly journals Role of blue and red light in stomatal dynamic behaviour

2019 ◽  
Vol 71 (7) ◽  
pp. 2253-2269 ◽  
Author(s):  
Jack S A Matthews ◽  
Silvere Vialet-Chabrand ◽  
Tracy Lawson
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Light Response ◽  
Early Morning ◽  
Stomatal Opening ◽  
Carbon Gain ◽  
Blue Light Response ◽  
Order Of Magnitude ◽  
Photosynthetic Responses ◽  
Novel Target

Abstract Plants experience changes in light intensity and quality due to variations in solar angle and shading from clouds and overlapping leaves. Stomatal opening to increasing irradiance is often an order of magnitude slower than photosynthetic responses, which can result in CO2 diffusional limitations on leaf photosynthesis, as well as unnecessary water loss when stomata continue to open after photosynthesis has reached saturation. Stomatal opening to light is driven by two distinct pathways; the ‘red’ or photosynthetic response that occurs at high fluence rates and saturates with photosynthesis, and is thought to be the main mechanism that coordinates stomatal behaviour with photosynthesis; and the guard cell-specific ‘blue’ light response that saturates at low fluence rates, and is often considered independent of photosynthesis, and important for early morning stomatal opening. Here we review the literature on these complicated signal transduction pathways and osmoregulatory processes in guard cells that are influenced by the light environment. We discuss the possibility of tuning the sensitivity and magnitude of stomatal response to blue light which potentially represents a novel target to develop ideotypes with the ‘ideal’ balance between carbon gain, evaporative cooling, and maintenance of hydraulic status that is crucial for maximizing crop performance and productivity.

scholarly journals Chiral changes of cortical microtubule orientations in epidermls of sunflower hypocotyls. The effect of blue and red light

2011 ◽  
Vol 76 (4) ◽  
pp. 269-275 ◽  
Author(s):  
Agata Burian
Keyword(s):  
Blue Light ◽  
Epidermal Cell ◽  
Cell Walls ◽  
Cortical Microtubule ◽  
Red Light ◽  
Developmental Processes ◽  
Lower Region ◽  
Special Regard ◽  
Left Handed ◽  
Cell Position

Light and developmental processes affect the cortical microtubule (cMT) orientation. The cMT orientation with a special regard to its chirality was analyzed under the outer epidermal cell walls in different regions of sunflower hypocotyls kept in darkness and after irradiation with blue and red light. The results show that the cMT orientation depends on the cell position along hypocotyl, but generally cMTs are oblique. The oblique orientation has defined chirality: either of Z-form (right-handed) or S-form (left-handed). In the lower region of hypocotyls the Z-form dominates. After irradiation of hypocotyls with blue light this domination has been maintained and appeared also in the upper region. In contrast, after irradiation with red light the Z-form domination has not been apparent. It is proposed that in darkness, variations of cMT orientations in the epidermis along the hypocotyl are due to developmental processes, while blue and red light affect the cMT orientation via "shifting" these processes backward and forward, respectively.

scholarly journals Transcriptomic and Metabolomic Profiling Reveals the Effect of LED Light Quality on Fruit Ripening and Anthocyanin Accumulation in Cabernet Sauvignon Grape

2021 ◽  
Vol 8 ◽  
Author(s):  
Peian Zhang ◽  
Suwen Lu ◽  
Zhongjie Liu ◽  
Ting Zheng ◽  
Tianyu Dong ◽  
...  
Keyword(s):  
Blue Light ◽  
White Light ◽  
Plant Traits ◽  
Soluble Sugars ◽  
Red Light ◽  
Green Light ◽  
Grape Berries ◽  
Light Spectra ◽  
Metabolomic Profiling ◽  
Highly Expressed Genes

Different light qualities have various impacts on the formation of fruit quality. The present study explored the influence of different visible light spectra (red, green, blue, and white) on the formation of quality traits and their metabolic pathways in grape berries. We found that blue light and red light had different effects on the berries. Compared with white light, blue light significantly increased the anthocyanins (malvidin-3-O-glucoside and peonidin-3-O-glucoside), volatile substances (alcohols and phenols), and soluble sugars (glucose and fructose), reduced the organic acids (citric acid and malic acid), whereas red light achieved the opposite effect. Transcriptomics and metabolomics analyses revealed that 2707, 2547, 2145, and 2583 differentially expressed genes (DEGs) and (221, 19), (254, 22), (189, 17), and (234, 80) significantly changed metabolites (SCMs) were filtered in the dark vs. blue light, green light, red light, and white light, respectively. According to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, most of the DEGs identified were involved in photosynthesis and biosynthesis of flavonoids and flavonols. Using weighted gene co-expression network analysis (WGCNA) of 23410 highly expressed genes, two modules significantly related to anthocyanins and soluble sugars were screened out. The anthocyanins accumulation is significantly associated with increased expression of transcription factors (VvHY5, VvMYB90, VvMYB86) and anthocyanin structural genes (VvC4H, Vv4CL, VvCHS3, VvCHI1, VvCHI2, VvDFR), while significantly negatively correlated with VvPIF4. VvISA1, VvISA2, VvAMY1, VvCWINV, VvβGLU12, and VvFK12 were all related to starch and sucrose metabolism. These findings help elucidate the characteristics of different light qualities on the formation of plant traits and can inform the use of supplemental light in the field and after harvest to improve the overall quality of fruit.

Control by Light Quality of Chlorophyll Synthesis in the Brown Alga Desmarestia aculeata

1991 ◽  
Vol 46 (7-8) ◽  
pp. 542-548 ◽  
Author(s):  
F. López-Figueroa
Keyword(s):  
Blue Light ◽  
Light Quality ◽  
Red Light ◽  
Green Light ◽  
Chlorophyll Synthesis ◽  
Natural Conditions ◽  
Light Pulses ◽  
Light Effects ◽  
Starvation Conditions

Abstract The chlorophyll synthesis in the brown algae Desmarestia aculeata is affected by light quality and by the nutrient state in the medium before the illumination. Pulses of 5 min of red, green and blue light together with 200 μM nitrate in plants growing under natural conditions deter­ mined similar induction of chlorophyll synthesis. However, when the plants were incubated previously under starvation conditions the light effect was different. The induction of chlorophyll synthesis was greater after blue and green light than after red light pulses. Red-light photoreceptor was only involved in the chlorophyll synthesis under no nutrient limitations and under starvation conditions after previous illumination with blue light followed by far-red light. The induction of chlorophyll synthesis by green and blue light pulses applied together with nitrate was greater when the algae were incubated in starvation conditions than in natural conditions (normal nutrient state). Because all light effects were partially reversed by far-red light the involvement of a phyto-chrome-like photoreceptor is proposed. In addition, a coaction between blue-and a green-light photoreceptors and phytochrome is suggested.

scholarly journals Blue Light Activates the σB-Dependent Stress Response of Bacillus subtilis via YtvA

2006 ◽  
Vol 188 (17) ◽  
pp. 6411-6414 ◽  
Author(s):  
Marcela Ávila-Pérez ◽  
Klaas J. Hellingwerf ◽  
Remco Kort
Keyword(s):  
Bacillus Subtilis ◽  
Stress Response ◽  
Blue Light ◽  
Promoter Activity ◽  
Red Light ◽  
Light Response ◽  
Soil Bacterium ◽  
Light Illumination ◽  
Present Evidence ◽  
General Stress Response

ABSTRACT Here we present evidence for a physiologically relevant light response mediated by the LOV domain-containing protein YtvA in the soil bacterium Bacillus subtilis. The loss and overproduction of YtvA abolish and enhance, respectively, the increase in σB-controlled ctc promoter activity at moderate light intensities. These effects were absent in the dark and in red light but present under blue-light illumination. Thus, activation of the general stress response in B. subtilis is modulated by blue light.

scholarly journals Dual and Multi-Emission Hybrid Micelles Realized through Coordination-Driven Self-Assembly

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 440
Author(s):  
Youxiong Zheng ◽  
Yan Tang ◽  
Jianwei Yu ◽  
Lan Xie ◽  
Huiyou Dong ◽  
...  
Keyword(s):  
Blue Light ◽  
White Light ◽  
Self Assembly ◽  
Light Emission ◽  
Raft Polymerization ◽  
Red Light ◽  
Green Light ◽  
Assembly Process ◽  
Blue Light Emission ◽  
Dual Emission

Building novel functional nanomaterials with a polymer is one of the most dynamic research fields at present. Here, three amphiphilic block copolymers of 8-hydroxyquinoline derivative motifs (MQ) with excellent coordination function were synthesized by Reversible Addition-Fragmentation Chain Transfer Polymerization (RAFT) polymerization. The coordination micelles were prepared through the self-assembly process, which the MQ motifs were dispersed in the hydrophobic polystyrene (PSt) blocks and hydrophilic Poly(N-isopropylacrylamide (PNIPAM)) blocks, respectively. The dual-emission micelles including the intrinsic red light emission of quantum dots (QDs) and the coordination green light emission of Zn2+-MQ complexes were built by introducing the CdSe/ZnS and CdTe/ZnS QDs in the core and shell precisely in the coordination micelles through the coordination-driven self-assembly process. Furthermore, based on the principle of three primary colors that produce white light emission, vinyl carbazole units (Polyvinyl Carbazole, PVK) with blue light emission were introduced into the hydrophilic PNIPAM blocks to construct the white light micelles that possess special multi-emission properties in which the intrinsic red light emission of QDs, the coordination green light of Zn2+-MQ complexes, and the blue light emission of PVK were synergized. The dual and multi-emission hybrid micelles have great application prospects in ratiometric fluorescent probes and biomarkers.

EFFECT OF WHITE, RED, AND BLUE LIGHT ON THE NATURE OF THE PRODUCTS OF PHOTOSYNTHESIS IN TOBACCO LEAVES

1962 ◽  
Vol 40 (2) ◽  
pp. 317-326 ◽  
Author(s):  
E. B. Tregunna ◽  
G. Krotkov ◽  
C. D. Nelson
Keyword(s):  
Carbon Dioxide ◽  
Blue Light ◽  
Soluble Fraction ◽  
Incident Light ◽  
Soluble Sugars ◽  
Red Light ◽  
Considerable Decrease ◽  
Tobacco Leaves ◽  
Tentative Explanation ◽  
Photosynthetic Products

Detached tobacco leaves were placed singly into a photosynthesis chamber and illuminated in the presence of C14O2 with white, red, or blue light. Two kinds of experiments were carried out. In the first, the energy of the three kinds of incident light was adjusted so that the rate of CO2 uptake was the same. In the second, the energy of the three kinds of incident light was the same and the time adjusted so that an equal amount of CO2 was taken up by each leaf. At the end of photosynthesis the distribution of C14 was determined in the ethanol-soluble and-insoluble fractions and among the various compounds of the ethanol-soluble fraction that were separated by paper chromatography.No effect of wavelength of light was observed on the distribution of absorbed carbon dioxide between the ethanol-soluble and -insoluble fractions. Neither was there any evidence that red light stimulated synthesis of soluble sugars. Red light, compared with white, increased incorporation of carbon dioxide into glycine, but had no effect on serine. Blue brought about a considerable decrease in glycine and some decrease in serine.A tentative explanation is given of a mechanism by means of which the wavelength of light may affect the distribution of absorbed carbon dioxide among the various photosynthetic products.

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