The HY5 transcription factor negatively regulates ethylene production by inhibiting ACS1 expression under blue light conditions in pear

Ethylene is the main factor controlling fruit ripening of pear(Pyrus ussuriensis).Ethylene production rate is negatively correlated with fruit shelf life;therefore,it is important to decrease the ethylene levels for optimal fruit storage.Here,we observed that blue light treatment could inhibit ethylene production and promote the expression of ELONGATED HYPOCOTYL 5(PuHY5),a basic leucine zipper domain(bZIP)transcription factor.The following studies showed that PuHY5 could bind to the promoter of ACC synthase 1(PuACS1),a rate-limiting enzyme in ethylene biosynthesis,and inhibit its expression.For pears in which Pu HY5 was silenced,the ethylene production and PuACS1 expression were much higher than those in the control fruit.These results demonstrated that blue light inhibited ethylene production through the induction of Pu HY5 in pear.Our finding provides a new method for prolonging fruit shelf life.

Blue light induces leaf color change by modulating carotenoid metabolites in orange-head Chinese cabbage(Brassica rapa L.ssp. pekinensis)

Carotenoids are involved in the formation of plant leaf color as well as photosystem photoprotection. This study showed that blue light significantly induced up-regulation of the total carotenoid content in the inner leaves of orange-head Chinese cabbage(OHCC). Furthermore, the transcriptomic analysis revealed that blue light treatment induced upregulation of genes in photosynthesis(BrHY5-2, BrCOP1 and BrDET1) and the methylerythritol 4-phosphate pathways(BrGGPS, BrDXS and BrHDR) upstream of the carotenoid metabolic pathway. Carotenoid metabolomic analysis revealed that the accumulation of several orange and red carotenoids(lycopene, zeaxanthin, β-carotene, lutein, and β-cryptoxanthin) after blue light treatment contributed to the deepening of the leaf coloration, suggesting that short-term blue light treatment could be used to boost nutritional quality. The light signal gene BrHY5-2 participated in the blue light-induced transcriptional regulation of carotenoid biosynthesis in OHCC. Overexpression of BrHY5-2 in Arabidopsis significantly increased the total carotenoid content and the sensitivity to blue light. The above findings revealed new insights about blue-light-induced carotenoid synthesis and accumulation in OHCC lines. They suggested a new engineering approach to increase the nutritional value of vegetables.

Effects of Different Light Qualities on the Growth Characteristics of Populus trinervis

Populus trinervis is native to China and plays an irreplaceable role in maintaining the ecological balance of boreal and temperate forests.P.trinervis mainly grows in high-altitude areas.At present,there are limited studies on the response of P.trinervis to different light qualities,so it is necessary to investigate the photosynthetic physiological changes of P.trinervis in different light environments.In our study,P.trinervis was grown for 8 months under light filtered by three different colored films.The three treatments were blue film,green film,and white plastic film.The effects of blue(B),green(G),and white(W)light on photosynthetic pigment content,absolute growth,photosynthetic parameters,soluble sugar content,and chlorophyll fluorescence parameters were studied,respectively.Compared to the Wtreatment,the chlorophyll a and b,carotenoids,total chlorophyll content(a+b),absolute growth of seedling height,net photosynthetic rate(PN),water use efficiency(WUE),total soluble sugars,sucrose,and nonphotochemical quenching(NPQ)of P.trinervis were significantly increased under B treatment.Meanwhile,chlorophyll a and b,carotenoids,total chlorophyll(a+b),transpiration rate(Tr),intercellular CO_(2) concentration(Ci),stomatal conductance(gs),absolute growth of seedling height and leaf length,reducing sugar,total soluble sugar content,and NPQ were significantly increased under G treatment.The results showed that the absolute growth and chlorophyll content of P.trinervis were increased under B light,while the sugar and photosynthetic parameters were increased under G light.Additional studies may look into how B light impacts absolute growth and promotional mechanisms,as well as how G light affects the accumulation of sugar levels.

Supplemental blue and red light promote lycopene synthesis in tomato fruits

Lycopene, one of the strongest natural antioxidants known and the main carotene in ripe tomato, is very important for human health. Light is well known to be one of the most important environmental stimuli influencing lycopene biosynthesis; specifically, red light induces higher lycopene content in tomato. However, whether blue light promotes lycopene synthesis remains elusive and exactly how light stimulation promotes lycopene synthesis remains unclear. We applied supplemental blue and red lighting on tomato plants at anthesis to monitor the effect of supplemental blue and red lighting on lycopene synthesis. Our results showed that supplemental blue/red lighting induced higher lycopene content in tomato fruits; furthermore, we found that the expression of key genes in the lycopene synthesis pathway was induced by supplemented blue/red light. The expression of light signaling components, such as red-light receptor phytochromes(PHYs), blue-light receptor cryptochromes(CRYs) and light interaction factors, phytochrome-interacting factors(PIFs) and ELONGATED HYPOCOTYL 5(HY5) were up-or down-regulated by blue/red lighting. Thus, blue and red light increased lycopene content in tomatoes by inducing light receptors that modulate HY5 and PIFs activation to mediate phytoene synthase 1(PSY1) gene expression. These results provide a sound theoretical basis for further elucidation of the light regulating mechanism of lycopene synthesis in tomatoes, and for instituting a new generation of technological innovations for the enhancement of lycopene accumulation in crop production.

Supplemental blue light increases growth and quality of greenhouse pak choi depending on cultivar and supplemental light intensity

To evaluate the supplementary blue light intensity on growth and health-promoting compounds in pak choi（Brassica campestris ssp.chinensis var.communis）,four blue light intensity treatments（T0,T50,T100 and T150 indicate 0,50,100,and 150μmol m^（-2） s^（-1）,respectively）were applied 10 days before harvest under greenhouse conditions.Both of cultivars（greenand red-leaf pak choi）under T50 had the highest yield,content of chlorophyll and sugars.With light intensity increasing,antioxidant compounds（vitamin C and carotenoids）significantly increased,while nitrate content showed an opposite trend.The health-promoting compounds（phenolics,flavonoids,anthocyanins,and glucosinolates）were significantly higher under supplementary light treatment than T0,so as the antioxidant capacity（2,2-diphenyl-1-picrylhydrazyl and ferric-reducing antioxidant power）.The species-specific differences in photosynthetic pigment and health-promoting compounds was found in green-and red-leaf pak choi.T50 treatment could be used for yield improvement,whereas T100 treatment could be applied for quality improvement.Results showed that blue light intensity can regulate the accumulation of biomass,morphology and health-promoting compounds in pak choi under greenhouse conditions.

TiO_2/polyaniline composites:An efficient photocatalyst for the degradation of methylene blue under natural light

Polyaniline （PAn） sensitized nanocrystalline TiO2 composites （TiO2/PAn） were successfully prepared and used as an efficient photocatalyst for the degradation of dye methylene blue （MB）. The results showed that PAn was able to sensitize TiO2 efficiently and the composite photocatalyst could be activated by absorbing both the ultraviolet and visible light （λ： 190 ～ 800 nm）, whereas pure TiO2 absorbed ultraviolet light only （λ 〈 380 nm）. Under the irradiation of natural light, MB could be degraded more efficiently on the TiO2/PAn composites than on the TiO2 Furthermore, it could be easily separated from the solution by simple sedimentation.

Research progress about the effect and prevention of blue light on eyes

In recent years, people have become increasingly attentive to light pollution influences on their eyes. In the visible spectrum, short-wave blue light with wavelength between 415 nm and 455 nm is closely related to eye light damage. This high energy blue light passes through the cornea and lens to the retina causing diseases such as dry eye, cataract, age-related macular degeneration, even stimulating the brain, inhibiting melatonin secretion, and enhancing adrenocortical hormone production, which will destroy the hormonal balance and directly affect sleep quality. Therefore, the effect of Blu-rays on ocular is becoming an important concern for the future. We describe blue light’s effects on eye tissues, summarize the research on eye injury and its physical prevention and medical treatment.

Transcriptome analysis of carotenoid biosynthesis in Dunaliella salina under red and blue light

The quality of light is an important abiotic factor that affects the growth and development of photosynthetic organisms.In this study,we exposed the unicellular green alga Dunaliella salina to red(660 nm)and blue(450 nm)light and analyzed the cell growth,total carotenoid content,and transcriptomes.The growth of D.salina was enhanced by illumination with red light,whereas blue light was not able to promote the algal growth.In contrast,the total carotenoid content increased under both red and blue light.The RNA of D.salina was sequenced and the transcriptomic response of algal cells to red and blue light was investigated.Six transcripts encoding for the blue light receptor cryptochrome were identified,and transcripts involved in the carotenoid metabolism were up-regulated under both red and blue light.Transcripts encoding for photoprotective enzymes related to the scavenging of reactive oxygen species were up-regulated under blue light.The present transcriptomic study provides a more comprehensive understanding of carotenoid biosynthesis in D.salina under different wavelengths of light.

Photocatalytic degradation of methylene blue by nanostructured Fe/FeS powder under visible light

The photocatalytic performance of mechano-thermally synthesized Fe/FeS nanostructures formed from micron-sized starting materials was compared with that of a thermally synthesized nanostructure with nano-sized precursors in this paper. The properties of as-synthesized materials were studied by X-ray diffraction（XRD）, transmission electron microscopy（TEM）, vibrating sample magnetometry（VSM）, diffuse reflectance spectroscopy（DRS）, and ultraviolet–visible（UV-Vis） spectroscopy. The effects of irradiation time, methylene blue（MB） concentration, catalyst dosage, and p H value upon the degradation of MB were studied. Magnetic properties of the samples showed that both as-synthesized Fe/FeS photocatalysts are magnetically recoverable, eliminating the need for conventional filtration steps. Degradation of 5 ppm of the MB solution by mechano-thermally synthesized Fe/FeS with a photocatalyst dosage of 1 kg/m^3 at pH 11 can reach 96% after 12 ks irradiation under visible light. The photocatalytic efficiency is higher in alkaline solution. The kinetics of photocatalytic degradation in both samples is controlled by a first-order reaction. However, the rate-constant value in the thermally synthesized Fe/FeS photocatalyst sample is only 1.5 times greater than that of the mechano-thermally synthesized one.

Review of blue perovskite light emitting diodes with optimization strategies for perovskite film and device structure

Perovskite light emitting diodes(PeLEDs)have attracted considerable research attention because of their external quantum efficiency(EQE)of>20%and have potential scope for further improvement.However,compared to red and green PeLEDs,blue PeLEDs have not been extensively investigated,which limits their commercial applications in the fields of luminance and full-color displays.In this review,blue-PeLED-related research is categorized by the composition of perovskite.The main challenges and corresponding optimization strategies for perovskite films are summarized.Next,the novel strategies for the design of device structures of blue PeLEDs are reviewed from the perspective of transport layers and interfacial layers.Accordingly,future directions for blue PeLEDs are discussed.This review can be a guideline for optimizing perovskite film and device structure of blue PeLEDs,thereby enhancing their development and application scope.

Effects of Different Combinations of Red and Blue Light on Morphology and Photosynthetic Characteristic of Tomato Seedlings

Blue and red light are spectral wavelengths more effective for plants. The effects of different ratios of red and blue light （R/B=2, R/B=4, R/B=8, R/B=12） provided by LEDs on morphology and photosynthetic characteristics of tomato seedlings were studied. The results showed that plant height, stem diameter, fresh weight, dry weight, seedling index and G value increased with the increase of R/B ratio until 8. On the contrary, SPDA value decreased with the increase of R/B ratio. Photosynthetic characteristics were measured by CO 2 assimilation （ Pn ）, stomatal conductance （ gs ） and intracellular CO 2 concentration （ Ci） . Pn and gs decreased with the increase of R/B ratio. Furthermore, similar trend was investigated in photochemical quenching （qP） and electron transport rate （ETR）. Results of this study suggest that compared with white LED, appropriate combination of red and blue light can enhance plant growth and photosynthetic characteristics, and the optimal blue/red ratio for tomato growth was R/B=8.

Pure blue and white light electroluminescence in a multilayer organic light-emitting diode using a new blue emitter

We characterized the 6,12-bis{[N-（3,4-dimethylphenyl）-N-（2,4,5-trimethylphenyl）]amino} chrysene （BmPAC）, which has been proven to be a blue fluorescent emission with high EL efficiency. The blue fluorescent device exhibits good performance with an external quantum efficiency of 5.8% and current efficiency of 8.9 cd/A, respectively. Using BmPAC, we also demonstrate a hybrid phosphorescence/fluorescence white organic light-emitting device （WOLED） with high efficiency of 36.3 cd/A. In order to improve the relative intensity of blue light, we plus a blue light-emitting layer （BEML） in front of the orange light emitting layer （YEML） to take advantage of the excess singlet excitons. With the new emitting layer of BEML/YEML/BEML, we demonstrate the fluorescence/phosphorescence/fluorescence WOLED exhibits good performance with a current efficiency of 47 cd/A and an enhanced relative intensity of blue light.

Transcriptome analysis reveals effects of red and blue lightemitting diodes(LEDs)on the growth,chlorophyll fluorescence and endogenous plant hormones of potato(Solanum tuberosum L.)plantlets cultured in vitro

Red and blue light illumination has been reported to significantly affect plantlet growth.Potato is an important food and feed crop in the world and potato plantlet cultured in vitro plays an important role in potato production.However,few studies have documented the effects of red and blue light on the growth of potato plantlets revealed at the transcriptome level.The objective of this study was to determine the growth and physiological responses of potato plantlets cultured in vitro under monochromatic red(RR),monochromatic blue(BB)as well as combined red and blue(RB)LEDs using the RNA-Seq technique.In total,3150 and 814 differentially expressed genes(DEGs)were detected in potato plantlets under RR and BB,respectively,compared to RB(used as control).Compared to the control,the DEGs enriched in"photosynthesis"and"photosynthesis-antenna proteins"metabolic pathways were up-regulated and down-regulated by BB and RR,respectively,which might be responsible for the increases and decreases of maximum quantum yield(F_(v)/F_(m)),photochemical quantum yield(φ_(PSII)),photochemical quenching(q_(P))and electron transfer rate(ETR)in BB and RR,respectively.Potato plantlets exhibited dwarfed stems and extended leaves under BB,whereas elongated stems and small leaves were induced under RR.These dramatically altered plantlet phenotypes were associated with variable levels of endogenous plant hormones gibberellin(GAs),indoleacetic acid(IAA)and cytokinins(CKs),as assessed in stems and leaves of potato plantlets.In addition,monochromatic red and blue LEDs trigged the opposite expression profiles of DEGs identified in the"plant hormone signal transduction"metabolic pathway,which were closely related to the endogenous plant hormone levels in potato plantlets.Our results provide insights into the responses of potato plantlets cultured in vitro to red and blue LEDs at the transcriptomic level and may contribute to improvements in the micro-propagation of potato plantlets cultured in vitro from the light spectrum aspect.

A recent advances of blue perovskite light emitting diodes for next generation displays

The halide perovskite blue light emitting diodes(PeLEDs)attracted many researchers because of its fascinating optoelectrical properties.This review introduces the recent progress of blue PeLEDs which focuses on emissive layers and interlayers.The emissive layer covers three types of perovskite structures:perovskite nanocrystals(PeNCs),2-dimensional(2D)and quasi-2D perovskites,and bulk(3D)perovskites.We will discuss about the remaining challenges of blue PeLEDs,such as limited performances,device instability issues,which should be solved for blue PeLEDs to realize next generation displays.

High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

Levofloxacin （LOFX）, which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes （OLEDs）. In this paper, the fabricated white OLED contains a 452-nm blue emitting layer （thickness of 30 nm） with 1 wt% LOFX doped in CBP （4,4＇-bis（carbazol-9-yl）biphenyl） host and a 584-nm orange emitting layer （thickness of 10 nm） with 0.8 wt% DCJTB （4-（dicyanomethylene）-2-tert-butyl-6-（1,1,7,7- tetramethyljulolidin-4-yl-vinyl）-4H-pyran） doped in CBE which are separated by a 20-nm-thick buffer layer of TPBi （2,2＇,2＂-（benzene-1,3,5-triyl）-tri（1-phenyl-lH-benzimidazole）. A high color rendering index （CRI） of 84.5 and CIE chromaticity coordinates of （0.33, 0.32）, which is close to ideal white emission CIE （0.333, 0.333）, are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs.

Efficiency droop alleviation in blue light emitting diodes using the InGaN/GaN triangular-shaped quantum well

The InGaN/GaN blue light emitting diode（LED） is numerically investigated using a triangular-shaped quantum well model,which involves analysis on its energy band,carrier concentration,overlap of electron and hole wave functions,radiative recombination rate,and internal quantum efficiency.The simulation results reveal that the InGaN/GaN blue light emitting diode with triangular quantum wells exhibits a higher radiative recombination rate than the conventional light emitting diode with rectangular quantum wells due to the enhanced overlap of electron and hole wave functions（above 90%） under the polarization field.Consequently,the efficiency droop is only 18% in the light emitting diode with triangular-shaped quantum wells,which is three times lower than that in a conventional LED.

Effects of UV-B radiation on tetraspores of Chondrus ocellatus Holm(Rhodophyta),and effects of red and blue light on repair of UV-B-induced damage

We evaluated the effects of red and blue light on the repair of UV-B radiation-induced damage in tetraspores of Chondrus ocellatus Holm. Tetraspores of C. ocellatus were treated with different UV-B radiation levels(0,36,72,108,144 and 180 J/m2),and thereafter subjected to PAR,darkness,or red or blue light during a 2-h repair stage,each day for 48 days. The diameters and cellular contents of cyclobutane pyrimidine dimmers(CPDs),chlorophyll a(Chl a),phycoerythrin,and UV-B-absorbing mycosporinelike amino acids(MAAs) contents of the tetraspores were determined. Our results show that low doses of UV-B radiation(36 and 72 J/m 2) promoted the growth of C. ocellatus; however,increased UV-B radiation gradually reduced the C. ocellatus growth(greater than 72 J/m2). The MAAs(palythine and asterina-330) in C. ocellatus were detected and analyzed by LC/MS. Our results suggest that moderate red light could induce the growth of this alga in aquaculture. In addition,photorepair was inhibited by red light,so there may be some other DNA repair mechanism activated by red light. Blue light promoted the activity of DNA photolyase,greatly improving remediation efficiency. Red and blue lights were found to reduce the capacity of C. ocellatus to form MAAs. Therefore,PAR,red light,and blue light play different roles during the repair processes for damage induced by UV-B radiation.

Whole transcriptome analysis on blue light-induced eye damage

AIM:To analyze abnormal gene expressions of mice eyes exposed to blue light using RNA-seq and analyze the related signaling pathways.METHODS:Kunming mice were divided into an experimental group that was exposed to blue light and a control group that was exposed to natural light.After 14 d,the mice were euthanized and their eyeballs were collected.Whole transcriptome analysis was attempted to analyze the gene expression of the eyeballs using RNA-seq to reconstruct genetic networks.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis were used to reveal the related signaling pathways.RESULTS:The 737 differentially expressed genes were identified,including 430 up and 307 down regulated genes,by calculating the gene FPKM in each sample and conducting differential gene analysis.GO and KEGG pathway enrichment analysis showed that blue light damage may associated with the visual perception,sensory perception of light stimulus,phototransduction,and JAKSTAT signaling pathways.Differential lnc RNA,circ RNA and mi RNA analysis showed that blue light exposure affected pathways for retinal cone cell development and phototransduction,among others.CONCLUSION:Exposure to blue light can cause a certain degree of abnormal gene expression and modulate signaling pathways in the eye.

Effects of blue light on gametophyte development of Laminaria japonica (Laminariales, Phaeophyta)

Laminaria gametophyte was greatly influenced by light in its growth and development. Using light-emitting diodes (LED) as blue and red light sources, we analyzed the light effect on gametophytes devel- opment of Laminaria japonica Aresch. The gametophytes were obtained from zoospores collected in April, May, July, 2003 and September, 2004. We found that the growth of gametophytes was stimulated by increasing inten- sity of blue light (BL) and red light (RL) illumination, of which BL was obviously stronger than that of RL. The fertilization of gametophytes depended largely on BL, and only sufficient BL illumination could take the repro- ductive effect. In addition, we noticed that there was a significant difference in light responses for gametophytes developed from zoospore collected in different times. For zoospores released in April, under BL1 (73.90 μmol photons/m·s), the unicellular female gametophytes and multi-cellular male gametophytes produced eggs and sperms respectively, and further developed towards sporophytes. However, for gametophytes developed in May, July or September, they became multi-cellular and never formed oogonia or antheridia. It is believed that the Laminaria sporangium maturation stage could affect the gametophytes reaction to BL under laboratory culture conditions. Therefore, cryptochrome- or phototropin-like BL photoreceptors is probably involved in BL-induced development of Laminaria gametophytes.

Oxidative stress and mitochondrial dysfunction of retinal ganglion cells injury exposures in long-term blue light

AIM:To investigate the phototoxic effect of long-term excessive narrow-band blue light in staurosporine-induced differentiated retinal ganglion cells-5(SSRGC-5).METHODS:SSRGC-5 cells were divided into two groups,blue light group(BL group)and control group.Cell viability was assessed by using CCK-8 assay.Metabolic profile analysis was performed by using Seahorse extracellular flux analyzer.Mitochondria ultrastructure were studied via transmission electron microscope(TEM).Mitochondria contents and oxidative stress was evaluated by flow cytometry.Western blotting was performed to monitor the changes in mitogen-activated protein kinases(MAPK)pathway and PI3 K/AKT pathway.RESULTS:Blue light caused morphological changes of SSRGC-5 cells.The cell viability was significantly decreased from 3 h in BL group.Intercellular ROS and mitochondrial superoxide levels were increased following blue light exposure.Metabolic profiling identified blue light induced SSRGC-5 cells to have severely compromised mitochondrial function.This was accompanied by impaired mitochondrial ultrastructure and remodeling,increased expression of the mitochondrial related proteins,and increased glycolysis as compensation.Moreover,the results showed that blue light induced higher expression of p-p38,p38,p-JNK,p-ERK,p-cJun,c-Jun,and p-AKT.CONCLUSION:These findings indicate that excessive narrow-band blue light induces oxidative stress and mitochondrial metabolic remodeling dysregulate in SSRGC-5 cells.Activated MAPK and AKT signaling pathways are involved in this process.