Effect Of Blue Light Research Articles

Synthesis and structural characteristics analysis of melanin pigments induced by blue light in Morchella sextelata.

Morchella sextelata, a highly sought-after edible mushroom worldwide, is evaluated based on its cap color as an essential commercial property indicator. In the present study, the effects of blue light on cap pigmentation in M. sextelata, as well as the synthesis and structural characteristics of melanin pigments within the cap were examined. The results showed that an increase in the proportion of blue light within the lighting environment promoted melanin synthesis and melanization of the cap. Transmission and scanning electron microscopy revealed the localization of melanin within the mycelium and its ultrastructural characteristics. The UV-visible analysis demonstrated that melanin exhibited a maximum absorption peak at 220 nm and possessed high alkaline solubility as well as acid precipitability. The structural characteristics of melanin were analyzed using FTIR, NMR, HPLC, and elemental analysis, which confirmed the presence of eumelanin, pheomelanin, and allomelanin in both brown and black caps. Furthermore, blue light can stimulate the synthesis of both eumelanin and pheomelanin. The obtained results can serve as the foundation for comprehending the mechanism by which light regulates color formation in mushrooms.

Bactericidal Effect of 405-nm LED Light against <i>Aggregatibacter Actinomycetemcomitans</i> Is Due Primarily to Disruption of Respiratory Chain Terminal Members Cytochrome <i>bd</i> Oxidase and Quinol Peroxidase

Irradiation with 405-nm visible violet LED light without additional photosensitizers decreased the viability of the aggressive periodontopathic bacterium Aggregatibacter actinomycetemcomitans. The number of CFU/mL decreased linearly on a logarithm chart versus irradiation time, with a 1-log reduction time of 1.32 min. The antimicrobial photodynamic effect of 405-nm LED light involved inhibition of the activity of membrane-bound cytochrome bd, a terminal quinone: oxygen oxidoreductase, and quinol peroxidase, a terminal quinone:H2O2 oxidoreductase. The 405-nm LED irradiation reduced minus oxidized difference spectrum showed that the 640-nm peak (α-peak of heme d) completely disappeared, and the height of the 556-nm (α-peak of hemes b and c) and Soret band (425 nm; γ-peak of hemes b, c, and d) was reduced to approximately half of the peak heights of non-irradiated controls. Survival of bacteria-injected silkworm larvae was also examined. Fifth-instar silkworm larvae were almost completely killed by approximately 40 h after bacterial injection, but almost all silkworm larvae irradiated with 405-nm LED light (20 mW/cm2 for 5 min, energy density: 6 J/cm2) survived, similar to controls not injected with bacteria, indicating that 405-nm LED light killed the injected bacteria. The bactericidal effect of 405-nm blue-light on A. actinomycetemcomitans is primarily due to disruption of cytochrome bd oxidase and quinol peroxidase of the respiratory chain.

Assessment of the Effect of Blue Light on Visual Acuity among College Students

Visual acuity is the acuteness or clarity of vision which is dependent on the shortness of the retinal focus within the eye, and the sensitivity of the interpretative faculty of the brain. It is expressed as a fraction, such as 20/20 or 6/6 which is the normal visual acuity. Poor or impaired visual acuity is expressed as 20/40 and below or 6/9 and below. Blue light, which is one of the visible rays from the sun and also an artificial constituent of many modern devices, is a source of illumination which among other factors strongly affects our visual acuity. The present rapid, steady advancement in technology has led to a great increase in our usage and exposure to blue light. It is not uncommon nowadays to easily find someone who spends his entire day on digital screen, and many times even a great deal of the nighttime is also spent on blue-light-emitting technologies. The aim of this study is to assess and determine how this blue light affects college students and perhaps their productivity. A descriptive cross-sectional study was conducted using the focus group discussion (FGD) technique amongst 100 college students across five departments in College of Health Sciences, Nnamdi Azikiwe University, Nnewi Campus. The mean age of the respondents was 22.06 years. More of the respondents were females (66%) while 34% were males. The prevalence of visual acuity impairment after a considerably long usage of blue light was 37%. The majority of the respondents (87%) use a light-emitting diode (LED) technology torch/lantern during their night studies. 82% also uses their mobile phones for their studies and other academic works in which they have to spend many hours at once on the screen. Many others are exposed to other sources of blue light, and more even combine usage of different sources of blue light at once. The prevalence of visual acuity status below 6/6 amongst the students was high, and this is worrisome with regards to its long term effects or cumulative effects on their vision. Adequate sensitization on the harmful effects of long exposure to blue lights, usage of blue light filters/glasses (photochromic lens, for instance), taking frequent breaks from digital screens, encouraging outdoor use of blue light screens, early and proper management of impaired vision and more intakes of foods that enhance eyesight are recommended.

Blue Light Therapy in the Management of Chronic Wounds: A Narrative Review of its Physiological Basis and Clinical Evidence

Introduction. Chronic wounds are a significant problem worldwide, with substantial cost to health care systems; thus, a minimally invasive and well-tolerated treatment is attractive. Blue light has shown promise in wound healing through the principle of photobiomodulation. Objective. This review examines the physiological effects of blue light on tissue and the hypothesis that appropriate application of blue light in conjunction with SOC improves wound healing compared with SOC alone. Methods. The authors searched in PubMed, Google Scholar, and the Cochrane Library to identify literature on the mechanism of action of blue light and then examined the clinical evidence. Results. Key physiological pathways of blue light include generation of ROS and nitric oxide, resulting in promotion of angiogenesis, reduced inflammation, and direct antimicrobial effects. These reactions are seen only at low doses; in fact, higher doses may be harmful to tissue. The only primary study with statistical analyses demonstrated wound area reduction of 51% (P =.007) in blue light–irradiated wounds compared with SOC alone. Conclusions. Blue light applied following a strict protocol is safe and shows promise in the management of chronic wounds. The current evidence is poor, however, and randomized trials are required to confirm its clinical utility.

Reproducible method for assessing the effects of blue light using in vitro human skin tissues.

High-intensity visible light (HEV), also referred to as blue light, has a wavelength of 400-500 nm and accounts for approximately one-third of the visible light. Blue light is also emitted from electronic devices and artificial indoor lighting. Studies have shown that exposure of human skin cells to light emitted from electronic devices, even as short as 1 h, can cause an increase in reactive oxygen species (ROS), apoptosis and necrosis. Despite comprising a significant portion of the light spectrum, the effects of HEV light have not been studied as extensively. This is in part due to a lack of suitable in vitro testing methods. This work was conducted in order to develop a reproducible testing method for assessing the effects of blue light on the skin. Testing was performed using a full thickness, 3D in vitro skin tissue model. Different exposure protocols were tested to (1) determine the biological effects of blue light on the skin and (2) to identify an appropriate exposure for routine testing of cosmetic materials that may protect the skin from blue light damage. Gene expression and protein biomarkers were measured using qPCR, ELISA and immunohistochemical (IHC) methods. Our work demonstrates that daily exposure to blue light produced dose-and-time-dependent changes in biomarkers associated with skin damage. Exposure to blue light for 6 h for 5 consecutive days (total intensity of 30 J/cm2 ) increased the expression of genes that regulate inflammation and oxidative stress pathways and decreased the expression of genes that maintain skin barrier and tissue integrity. Exposure to blue light significantly increased protein biomarkers associated with ageing, inflammation and tissue damage. IHC staining confirmed changes in collagen, filaggrin and NQO1 protein expression. Treatment with ascorbic acid inhibited the effects of blue light, demonstrating a role in protection from blue light. Our results showed that consistent blue light exposure produced skin damage via alterations in biological pathways that are associated with skin ageing. This work provides a new, reproducible in vitro testing method for assessing the effects of blue light on human skin using gene expression, protein ELISA and IHC staining.

Blue Light Simultaneously Induces Peel Anthocyanin Biosynthesis and Flesh Carotenoid/Sucrose Biosynthesis in Mango Fruit.

Previous studies focused on the effects of light on fruit appearance, especially the peel color. However, the effect of light on fruit internal quality and the underlying mechanisms are unclear. In this study, we analyzed the effects of blue light on the appearance and internal quality of mango fruit (Mangifera indica L.). Blue light simultaneously induced peel anthocyanin and flesh sucrose/carotenoid biosynthesis in mango fruit. Analyses of co-expression networks and gene expression trends in mango fruit peel and flesh identified candidate genes, including transcription factor genes, involved in blue light-regulated anthocyanin, carotenoid, and sucrose biosynthesis pathways. Key blue light signaling-related genes (MiCRY and MiHY5) and blue light-triggered phytohormones were involved in these pathways. Additionally, there were common and tissue-specific pathways for the blue light-promoted accumulation of anthocyanins, carotenoids, and sucrose. Our results provide new insights into the regulatory effects of light on the appearance and internal quality of mango fruit.

Effects of Morning or Evening Narrow-band Blue Light on the Compensation to Lens-induced Hyperopic Defocus in Chicks.

Exposure to blue light before bedtime is purported to be deleterious to various aspects of human health. In chicks, blue evening light stimulated ocular growth, suggesting a role in myopia development. To further investigate this hypothesis, we asked if brief blue light altered the compensatory responses to hyperopic defocus. Previous work showed that several hours' evening exposure to blue light stimulated ocular growth in chicks, but morning exposure was only effective at a lower illuminance. By contrast, rearing in blue light has inhibited ocular growth in untreated eyes and eyes exposed to form deprivation or defocus. We studied the effects of brief exposures to blue light on the compensation to hyperopic defocus. Chicks wore monocular negative lenses (-10 D) starting at age 10 days. They were subsequently exposed to blue light (460 nm) for 4 hours in the morning or evening for 8 to 9 days ("dim," 200 lux[morning, n = 9; evening, n = 11]; "bright," 600 lux[morning, n = 8; evening, n = 20]); controls wore lenses in white light (n = 14). Ultrasonography was done on days 1, 5, 8, and 9 for "evening" groups and days 1, 6, and 8 for "morning." All data are reported as interocular differences (experimental minus fellow eyes). Refractions were measured on the last day. For evening exposure, dim blue light enhanced the axial compensation at all times (change in axial length: day 6: 465 vs. 329 μm/9 days, analysis of variance P < .001, P = .03; day 9: 603 vs. 416 μm/9 days, analysis of variance P < .001; P < .05). Bright blue light had a transient inhibitory effect (day 5: 160 vs. 329 μm; P < .005). Refractive errors were consistent with axial growth, with dim causing more myopia than bright (-9.4 vs. -4.7 D; P < .05). Morning blue light had no significant effect. We speculate that these findings reflect a complex interaction between illuminance, defocus, and time of day.

Adverse Effect of Blue Light on DNA Integrity Is Accelerated by 5-Aminolevulinic Acid in HaCaT Human Keratinocyte Cells and B16F1 Murine Melanoma Cells.

Several studies have suggested the potential benefits of 5-aminolevulinic acid (5-ALA)-based photodynamic therapy (PDT). 5-ALA is a precursor of heme, which generates reactive oxygen species (ROS) following photoirradiation. Some reports indicate that blue light induces intracellular ROS production. In the present study, we elucidated the effects of blue light and 5-ALA on DNA integrity in B16F1 murine melanoma and human keratinocyte HaCaT cells using a variety of comet assay techniques. Co-treatment with blue light and 5-ALA significantly decreased cell viability in both cell lines. A neutral comet assay was performed to assess DNA double-strand break (DSB) formation and blue light and 5-ALA caused DSBs. We also performed an alkali comet assay to detect single-strand breaks (SSB) and alkali labile sites (ALS). The results indicated that 5-ALA accelerated blue light-induced SSB formation. In addition, modified comet assays were done using two types of enzymes to evaluate oxidative DNA damages. The results indicated that blue light and 5-ALA generated oxidized purine and pyrimidines in both cell lines. In summary, co-treatment with 5-ALA and photoirradiation may cause unexpected DNA damage in cells and tissues.

Light conditions affect the growth, chemical composition, antioxidant and antimicrobial activities of the white-rot fungus Lentinus crinitus mycelial biomass.

The mycelial biomass of basidiomycetes is a promising source of compounds and represents an alternative for industrial and biotechnological applications. Fungi use light as information and hold photoresponse mechanisms, in which sensors respond to light wavelengths and regulate various biological processes. Therefore, this study aimed to investigate the effects of blue, green, and red lights on the growth, chemical composition, and antioxidant and antimicrobial activity of Lentinus crinitus mycelial biomass. The chemical composition of the mycelial biomass was determined by chromatographic methods, antioxidant activity was analyzed by in vitro assays, and antimicrobial activity was investigated by the microdilution assay. The highest mycelial biomass yield was observed under blue-light cultivation. Many primordia arose under blue or green light, whereas the stroma was formed under red light. The presence of light altered the primary fungal metabolism, increasing the carbohydrate, tocopherol, fatty acid, and soluble sugar contents, mostly mannitol, and reducing the protein and organic acid concentrations. Cultivation under red light increased the phenol concentration. In contrast, cultivation under blue and green lights decreased phenol concentration. Benzoic and gallic acids were the main phenolic acids in the hydroalcoholic extracts, and the latter acids increased in all cultures under light, especially red light. Mycelial biomass cultivated under red light showed the highest antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The ferric reducing antioxidant power (FRAP) method showed that all light wavelengths increased the antioxidant activity of mycelial biomass, with the highest value under red light. Moreover, the β-carotene/linoleic acid co-oxidation (BCLA) assay demonstrated that the antioxidant activity was affected by light cultivation. Mycelial biomass grown under all conditions exhibited antibacterial and antifungal activities. Thus, mycelial biomass cultivation of L. crinitus under light conditions may be a promising strategy for controlling the mycelial chemical composition and biomass yield.

Blue light irradiation alleviated dextran sulfate sodium-induced colitis mediated by the Bmal1 pathway in macrophages

Patients with long-term or severe inflammatory bowel disease (IBD) are more likely to develop colorectal cancer. The mortality rate of patients with IBD-related colorectal cancer is also higher than that of patients with common colorectal cancer. This study focused on the effect of photobiomodulation (PBM) on dextran sulfate sodium (DSS)-induced colitis and its underlying mechanism. C57 mice were treated with monochromatic light during DSS-induced colitis. Blue light irradiation clearly alleviated DSS-induced colitis, significantly changed the proportion of the relevant immune cell population in the colon, and improved the inflammatory environment of the colon. Moreover, the rhythm gene Brain And Muscle ARNT-Like 1 (Bmal1) is involved in the progression of colitis, and its decreased expression in colitis mice was reversed by blue light irradiation. These data demonstrated that the protective effect of blue light against colitis is mediated by the Bmal1-mediated pathway in macrophages. This study proposes blue light irradiation with specific light intensities as a potential IBD therapy.

Proteomic, Physiological, and Anatomical Analyses Reveal the Effects of Red, Blue, and White Light on the Growth of Potato Plantlets under In Vitro Culture

Proteomic, Physiological, and Anatomical Analyses Reveal the Effects of Red, Blue, and White Light on the Growth of Potato Plantlets under In Vitro Culture

Effects of Red and Blue Light on Potato Leaf Senescence and Tuber-Seed Yield

Effects of Red and Blue Light on Potato Leaf Senescence and Tuber-Seed Yield

Senolytic Drug Quercetin Rescues Survival from Blue Light Toxicity in Drosophila Model.

With the increasing frequency of human exposure to blue light, the harmfulness of blue light has received wider attention. The damaging effect of blue light is complex and long-lasting. In this study, Drosophila melanogaster was used as a model organism to investigate the protective effect of the senolytic drug quercetin on blue light toxicity. As one of the first senolytic drugs discovered, quercetin not only has antioxidant properties, but also has been used to treat various neurological disorders. Our study shows that quercetin can effectively prolong the survival of flies under blue light irradiation, and it significantly increases the egg production of female flies under blue light. In addition, after flies intaking quercetin under blue light, both the spontaneous activity and nutrient metabolism show significant sex-specificity. The experimental results provide a potentially effective intervention method for organisms to defend against blue light toxicity, and reveal a new function of the senolytic drug quercetin from another perspective.

Transcriptome and targeted metabolome analysis revealed the effects of combined red and blue light on the growth and secondary metabolism of Scutellaria baicalensis Georgi

Scutellaria baicalensis Georgi is a medicinal plant commonly used in China and other parts of East Asia. A high flavonoid content endows it with multiple beneficial biological activities that have anti-inflammatory, antibacterial, antiviral, and anti-COVID19 properties. Light-emitting diodes (LEDs) have been recognized as effective artificial lights to enhance plant growth and the accumulation of secondary metabolites for commercial plant production. However, little is known regarding the effects of LEDs on S. baicalensis. Here, we explored the effects of monochromatic blue light (B, 460 nm), monochromatic red light (R, 660 nm), white light (CK), and different combinations of R and B (R9B1, R7B3, R5B5, R3B7, and R1B9) on the growth of, and flavonoid accumulation in S. baicalensis. The results revealed that under R:B ratios of 9:1 or 7:3, the whole plant and roots of S. baicalensis seedlings had a higher biomass and flavonoid content. Targeted metabolomics analysis showed that 48 differentially expressed metabolites (DEMs) were verified between different groups, and the number of upregulated DEMs, particularly flavonoids, were higher in the R9B1 and R7B3 groups compared with the CK. Transcriptome data identified 1412 and 1508 differentially expressed genes (DEGs) in the R9B1 and R7B3 groups, respectively, in contrast to the CK. KEGG pathway analysis indicated that DEGs in both the R9B1 and R7B3 groups were primarily enriched in the phenylpropane biosynthesis, plant hormone signal transduction, flavonoid biosynthesis, starch and sucrose metabolism, galactose metabolism, cartenoid biosynthesis, zeatin biosynthesis, and nitrogen metabolism pathways. The qRT-PCR results showed that SbPAL, SbCLL-7, SbCHI, SbFNS, and SbOMT encoding enzymes for the flavonoid biosynthesis pathway were significantly upregulated in S. baicalensis, which was consistent with the transcriptome data. Finally, based on correlation analysis between the main flavonoids in S. baicalensis and the genes encoding transcription factors and enzymes for the flavonoid metabolism pathway, a co-expression network map was developed, which provided a basis for the mining of light responsive genes related to flavonoids biosynthesis in S. baicalensis. This is the first report to articulate how the combination of red light and blue light influences the growth and secondary metabolism of S. baicalensis.

Knowledge of the Effects of UV Radiation and Blue Light on the Skin, the Proper use of Protective Cosmetics and Usage Patterns in Latvia

UV (ultraviolet) radiation is a significant risk factor for the development of skin cancers such as melanoma, basal cell carcinoma, and squamous cell carcinoma, and can contribute to other skin lesions.&#x0D; Objectives: The aim of the study was to find out knowledge on the effects of UV radiation and blue light on the skin, the correct use of protective equipment, and their using habits in the Latvian population. &#x0D; Materials and Methods: An anonymous questionnaire was used, which included 31 questions and 307 participants in the age group from 18 to 60 years, randomly selected were surveyed (243 (79%) - women, 64 (21%) - men).&#x0D; Results: Comparing the knowledge about the effects of UV radiation and the blue light on the skin between the age groups, a statistically significant difference was found between the age groups 21-25 and 51-60 (p &lt;0.001), as well as between 26-30 and 51-60 (p &lt;0.001). Analyzing the data, a statistically significant difference was obtained in the gender groups who didn’t sunbathe - men did not sunbathe statistically significantly less than women (p &lt;0.05). Only 21.2% of respondents were using SPF protective creams daily. 8.1% of respondents believe that the effects of tanning on the skin are negative.&#x0D; Conclusion: The level of knowledge on UV radiation, blue light and proper use of protectives are influenced by age, gender and occupation in Latvian population.

Blue, Rather Than Red Light Can Nudge Employees to Choose Delayed But Larger Wage Payment

Most businesses have been severely affected during the ongoing Coronavirus Disease 2019 (COVID-19) pandemic, as they lack sufficient cash reserves for turnaround in this devastated business environment. This study presents a nudge-based approach for encouraging employees to choose delayed but larger wage payment. Through two laboratory experiments and one field experiment, we found that blue light more likely promotes individuals choosing the farsighted intertemporal option (i.e., delayed but larger payment) than red light. We further investigated why blue light can promote such a farsighted decision and found that the intradimensional difference comparison—that is, comparing the difference between the two options in the time dimension (∆ time A,B) and the difference in the payoff dimension (∆ payoff A,B)—mediates the effect of blue (vs. red) light on intertemporal choice. The current study demonstrates the effectiveness of light color and provides a solution to nudge people to make farsighted choices.

Blue light induces biosynthesis of flavonoids in Epimedium sagittatum (Sieb.et Zucc.) Maxim. leaves, a study on a light-demanding medicinal shade herb

Light is one of the most important environmental factors in plant life activities, and it plays an important role in regulating the synthesis of plant secondary metabolites. As a light-demanding shade plant, Epimedium sagittatum has a typical secondary metabolic process under different light irradiations. However, few studies have investigated the changes in flavonoid contents in E. sagittatum under different light irradiations. In this study, the effects of different light irradiations, namely red light, yellow light, and blue light, on plant physiological characteristics and saikosaponin secondary metabolism are investigated in one-year-old E. sagittatum leaves collected after 10, 20, and 30 days of treatment. The average leaf area significantly increased by 55.11 %, 45.15 %, and 42.09 %, respectively (p < 0.05), after 10 days, 20 days, and 30 days of treatment with red light. The change in the average area of the E. sagittatum leaves was not significant after blue and yellow light treatment (p > 0.05). Red light, yellow light, and blue light significantly increased the chlorophyll content (SPAD value) of the E. sagittatum leaves (p < 0.05). Although red light treatment could increase the leaf area, it had no positive effect on the accumulation of flavonoids. Yellow light treatment significantly increased the epimedin C and icariin contents by 42.54 % and 15.02 %, respectively, to 108.24 ± 0.50 mg g−1 and 28.54 ± 0.14 mg g−1 at 30 days after treatment (p < 0.05). However, it was not conducive to the accumulation of epimedin A and epimedin B. The blue light treatment significantly increased the epimedin C, icariin and icariside Ⅱ contents by 29.42 %, 28.45 %, and 66.12 %, respectively, to 98.27 ± 0.44 mg g−1, 31.87 ± 0.51 mg g−1 and 2.85 ± 0.02 mg g−1 at 30 days after treatment (p < 0.05). However, it was not conducive to the accumulation of epimedin A and epimedin B. The effects of red light on the gene expression of the flavonoid synthesis pathway was limited, and it does not significantly improve its transcription level. In contrast, the expression of flavonoid synthesis related genes (4CL3, CHS2 and ANS) was significantly upregulated by the yellow light and the blue light (p < 0.05), especially the positive effect of the blue light. Blue light also significantly upregulated the expression levels of 4CL1, CHI1, UF3GT, and UF7GT (p < 0.05). Therefore, blue light has a more significant effect than yellow light on the regulation of icariin and icariside Ⅱ synthesis. The widely untargeted metabolome analysis further confirmed the positive effects of blue light on the synthesis of flavonoids. After filtering, 2191 high-quality metabolites were used to screen the differentially accumulated metabolites (DAMs). A total of 38 metabolites involved in flavonoid biosynthesis were identified, of which 17 flavonoids were significantly accumulated under the blue light treatment. We identified that icariin accumulated under the blue light treatment by the untargeted metabolome. Our study indicates that light conditions can be improved by blue light or with blue film covering to facilitate the accumulation of icariin during the ecological cultivation of E. sagittatum. Our study improves our understanding on shade plant responses to light, and helps to obtain more flavonoids by changing the light conditions during cultivation, which is highly important in the ecological cultivation of Chinese medicinal plants.

Blue light exposure enhances oxidative stress, causes DNA damage, and induces apoptosis signaling in B16F1 melanoma cells

Studies have shown that visible light, specifically blue light, adversely affects cells, tissues, organs, and organisms. We investigated the effect of blue light on apoptosis, DNA integrity, and transcription of apoptotic and melanogenic genes using B16F1 melanoma cells. In this study, cells were irradiated with 2–50 W/m2 blue light (465 nm) for several time duration. Exposure to blue light decreased cell viability, but the pan-caspase inhibitor Z-VAD-FMK rescued blue light-induced cell death. Blue light also inhibited cell proliferation and arrested the cell cycle. Blue light-irradiated cells displayed several apoptotic features, like depolarized mitochondrial membranes and enhanced caspase-3 activity. Furthermore, blue light induced strand breaks in the genomic DNA in a dose- and time-dependent manner but did not induce the formation of cyclobutene pyrimidine dimers. The cell cycle inhibitor p21 and the pro-apoptotic gene Bax were upregulated in blue light-exposed cells, whereas the anti-apoptotic gene Bcl-2 and the apoptosis inhibitor survivin were downregulated. The key enzyme in melanin synthesis, tyrosinase, was upregulated after high-intensity (50 W/m2) blue light exposure and downregulated after low-intensity (0.2 W/m2) blue light exposure. Our study demonstrates that blue light triggers apoptosis and some of its effects are similar to those of ultraviolet radiation.

Effect of Phytochrome Deficiency on Photosynthesis, Light-Related Genes Expression and Flavonoid Accumulation in Solanum lycopersicum under Red and Blue Light.

The effect of red (RL, 660 nm) and blue (BL, 450 nm) light on phy mutant tomato plants was studied. The rates of photosynthesis (Pn) and transpiration, the efficiency of the primary photochemical processes of photosynthesis, the contents of flavonoids and phenolic compounds, the low-molecular-weight antioxidant capacity (Trolox equivalent antioxidant capacity (TEAC)) of leaf extracts, and the expression of light-dependent genes were evaluated. Under RL, BL, and white fluorescent light (WFL), the Pn values decreased in the order: WT > phyb2 > phyaphyb2 > phyaphyb1phyb2, except for the Pn in phyb2 on BL. Phyb2 also had a larger number of stomata under BL and, as a result, it reached maximum transpiration. The noticeable accumulation of flavonoids and phenolic compounds was observed only in the phyb2 and phyaphyb2 mutants upon irradiation with BL, which agrees with the increased TEAC in the leaf extracts. We suggest that the increased antioxidant activity under PHYB2 deficiency and the maintenance of high photosynthesis under BL are based on an increase in the expression of the early signaling transcription factors genes BBX, HY5. The largest decrease in the content of flavonoids and TEAC was manifested with a deficiency in PHYB1, which is probably the key to maintaining the antioxidant status in BL plants.

Exploration of the effect of blue laser light on microRNAs involved in functional metabolism in D. officinale through RNA sequencing

Dendrobium officinale has remarkable medicinal functions and high economic value. Laser light sources are different from ordinary light sources in terms of the light emission mechanism and play important roles regulating functional metabolite synthesis in D. officinale. However, the mechanism by which miRNAs participate in regulating the D. officinale response to blue laser irradiation has not been reported. Previous studies found that the number of red leaves on plants treated with blue laser light was greater than that on plants treated with blue light and white light, and blue laser light was most effective at promoting the accumulation of total flavonoids, polysaccharides and alkaloids. RNA-seq was used to analyse the difference in the effects of lasers on D. officinale. KEGG analysis of the target genes of differentially expressed (DE) miRNAs showed that there were multiple blue laser response pathways, among which peroxisome, nitrogen metabolism, terpenoid biosynthesis, porphyrin and chlorophyll metabolism played central roles. Cytoscape interaction analysis of DE miRNA targets showed that novel_miR_248 most likely participates in the influence of blue laser irradiation on D. officinale. Content verification in D. officinale showed that blue laser light could also increase the total terpene, chlorophyll levels, nitrate reductase, glutamine synthase and glutamate dehydrogenase. Combined with the qPCR results, these findings showed that miR395b, miR827 and miR319l may participate in the blue laser signalling network through their target genes and then regulate the accumulation of functional metabolites in D. officinale. This study provides a scientific basis for the high-yield production of D. officinale.