Effect Of Red Light Research Articles

Transcriptome analysis reveals the differential regulatory effects of red and blue light on nitrate metabolism in pakchoi (Brassica campestris L.)

Pakchoi (Brassica campestris L. ssp. chinensis) is an important leafy vegetable. Various light spectra, especially red and blue light, play vital roles in the regulation of nitrate metabolism. Information on the effects of red and blue light on nitrate metabolism at the transcriptome level in pakchoi is still limited, so this study used RNA sequencing technology to explore this molecular mechanism. Through pairwise comparisons with white LED light, 3 939 and 5 534 differentially expressed genes (DEGs) were identified under red and blue light, respectively. By Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses, these unigenes were found to be involved in nitrate assimilation, plant–pathogen interaction, biosynthesis of secondary metabolites, and phenylpropanoid biosynthesis. The differential effects of light spectra on the nitrate concentration and metabolism-related enzyme activities were also confirmed at the physiological level. Several signal transduction modules, including Crys/Phys-COP1-HY5/HY5-like, were found to be involved in red and blue light-induced nitrate metabolism, and the transcript levels for this complex were consistent with the observed degree of nitrate assimilation. The expression patterns of 15 randomly selected DEGs were further validated using qPCR. Taken together, the results of this study could help improve our understanding of light spectrum-regulated nitrate metabolism in pakchoi at the transcriptome level.

The effect of blue and red LED light on the growth, egg production, egg quality, behavior, and hormone concentration of Hy-Line W-36 laying hens

A study was conducted to investigate the effect of blue and red light-emitting diode (LED) on performance, behavior, egg quality, and hormonal concentration of pullets and laying hens. A total of 1,000 Hy-Line W-36 birds were raised in a cage-free housing system consisting of two identical rooms, one equipped with blue-LED from 1 to 18 wk of age and red-LED from 19 to 31 wk of age, and the other with normal-LED bulbs throughout the study. The study was repeated the following year. Body weight was recorded monthly, and egg production was recorded daily. Egg quality, organ weight, tonic immobility (TI), heterophil-lymphocyte ratio, serum corticosterone, luteinizing hormone and melatonin were analyzed monthly after the egg production started. The results showed that birds raised in blue-LED had a significantly higher body weight during the pullet phase from 1 to 18 wk of age (P = 0.049). A higher relative egg yolk percentage was observed in the red-LED (P = 0.043) with a lower relative albumen percentage (P = 0.015) compared to the normal-LED light. Lower relative spleen weight was observed in the red-LED compared to the normal-LED (P = 0.027). There was no difference between the light treatments with respect to hen day egg production, brain weight, tonic immobility and hormone concentration. The effects of these lights on the overall production, health, and immune system are not completely understood. Hence, it is difficult to conclude that exposing birds to blue-LED in the pullet phase for improved growth and red-LED in the laying phase for earlier and greater egg production would benefit overall egg production.

Effects of photobiomodulation therapy with red LED on inflammatory cells during the healing of skin burns.

The aim of this study was to evaluate the effects of red light emitting diode (LED) photobiomodulation therapy protocol on inflammatory cells during the healing of third-degree skin burns. Fifty Wistar rats were randomly divided into control group (CTRL) (n = 25) and red group (RED) (n = 25), with subgroups (n = 5) for each time of euthanasia (7, 14, 21, 28, and 32days). Treatment animals were daily irradiated (630nm ± 10nm, 300 mW, 9J/cm2 per point, 30s, continuous emission mode) at the 4 angles of the wound (total: 36J/cm2). After specimen removal, histological sections were stained with hematoxylin and eosin for quantitative analysis of the inflammatory infiltrate (neutrophils and lymphocytes) under light microscopy. Greater number of inflammatory cells was observed in irradiated groups when compared to CTRL at 7, 14, 21, and 28days, but with statistically significant difference only at 14days (p = 0.02). At 32days, higher inflammatory cell value was observed in CTRL when compared to RED, but with no statistically significant difference (p = 0.91). The results suggest that red LED, according to the protocol used, modulates the number of inflammatory cells in the early stages of the healing of third-degree skin burns. Nevertheless, this low-intensity light therapy may not, be efficient in reducing the number of neutrophils and lymphocytes in advanced stages of the repair process of skin burns. Further studies with other therapy protocols are needed to assess the effects of this type of light on the inflammatory response of skin burns.

Effect of blue and red monochromatic light during incubation on the early post-embryonic development of immune responses in broiler chicken

ABSTRACT 1. The light regime during incubation can influence embryonic and post-embryonic life and its effects can be mediated by rhythmic melatonin production in the embryonic pineal gland. 2. This study explored whether the incubation of chick embryos under red or blue monochromatic light, which induces maximum and minimum melatonin production, respectively, can influence the development and reactivity of the immune system in chicks. 3. In hatchlings, basal expression of immune genes (AvBD-1, PSEN-1, and IL-6) was evaluated in the duodenum using real-time PCR. The expression of these genes was measured weekly for three weeks after hatching, 3 h after intraperitoneal lipopolysaccharide (LPS) injection. At these times, the heterophil/lymphocyte ratio (He/Ly) was evaluated on blood smears, plasma immunoglobulin Y (IgY) concentrations by ELISA and IL-6 gene expression in the spleen by real-time PCR were determined. 4. During development, the He/Ly ratio and plasma IgY concentration were not significantly influenced by the light quality during incubation. Red light increased gene expression of AvBD-1 in hatchlings and IL-6 in two-week-old chickens compared to birds incubated under blue light. The expression of IL-6 after LPS stimulation increased in an age-dependent manner, both in the duodenum and the spleen, reflecting the maturation of the immune system. 5. The results suggested that red light may increase the local immune response in the gut immediately after hatching, but this effect was not apparent during later development.

Whole-transcriptome RNA sequencing highlights the molecular mechanisms associated with the maintenance of postharvest quality in broccoli by red LED irradiation

Irradiation of green vegetables with different wavelengths of light represents a safe and effective technology that can be used to maintain postharvest quality. In this regard, our previous research demonstrated that red LED irradiation (50 μmol m−2 s−1) helped to delay the senescence of broccoli stored at room temperature. In the present study, a total of 20,246 differentially expressed mRNAs (DEGs), 3450 differentially expressed lncRNAs (DElncRNAs), and 135 differentially expressed miRNAs (DEmiRNAs) were identified in the response of broccoli to LED irradiation during storage, relative to non-irradiated broccoli. Results of the analysis of the DEG products indicated that the effect of red LED light on delaying senescence in broccoli stored at 20 °C involves an enhancement of genes involved in glucosinolate biosynthesis and the synthesis of chlorophyl a from glutamate. Red LED irradiation also delays increases in the expression of photosynthesis- and oxidative phosphorylation-related genes during the senescence of broccoli. This study provides insight into the molecular mechanisms associated with the response of broccoli to red LED irradiation, and confirms the potential of LED preservation technology.

Mixotrophic cultivation of microalgae to enhance the biomass and lipid production with synergistic effect of red light and phytohormone IAA

Microalgal cultivation still presents a big challenge in commercial application due to the small size and low density of microalgae. The effect of phytohormones or light spectra on enhancing microalgal growth has been individually demonstrated at the bench scale. However, the synergistic action of phytohormones and light spectra on algal growth and lipid production remains unclear. In this study, the optimal carbon and nitrogen concentrations, as well as the optimum dosage of the phytohormone indole-3-acetic acid (IAA), for the growth of Chlorella vulgaris were first evaluated under mixotrophic cultivation. A light spectrum experiment was then conducted in an incubator equipped with white and red light. Results show that optimal mixotrophic cultivation conditions were 10 g L−1 glucose, 2250 mg L−1 sodium nitrate and 10 mg L−1 IAA. Under the optimum IAA treatment and irradiation with red light, the highest biomass, lipid content and lipid productivity were 28.34%, 3.53 g L−1 and 140.04 mg L−1 d−1, respectively. As compared to white light, the synergistic action of red light and IAA stimulated biomass production and lipid accumulation by algal cell metabolism and carbon source bioconversion. Furthermore, the post-optimized C. vulgaris had the potential for biodiesel production. These results provide new insights for the highly efficient cultivation of microalgae.

Inhibitory Effects of Blue Light-Emitting Diode Irradiation on Podosphaera xanthii Conidial Release and Infection of Melon Seedlings

Powdery mildew fungi infect plant leaves, reducing the yield of infected melon plants. Therefore, an eco-friendly method of controlling powdery mildew in melon plants needs to be developed. A previous study described how the morphological characteristics of the conidiophores of the melon powdery mildew fungus Podosphaera xanthii Pollacci (designated KMP-6N) grown under greenhouse (natural) conditions and red light-emitting diode (LED) irradiation differed from those grown under growth chamber conditions and blue LED irradiation. In the present study, conidiophores with unconstricted conidia under blue light were collected and inoculated onto host leaves through micromanipulation; the unconstricted conidia germinated and infected the leaves, producing vigorously elongated hyphae. The number of conidia collected, the initial times of conidial release from single colonies, and the number of conidia remaining in chains on conidiophores were examined with electrostatic techniques. Under red light, the number of collected conidia gradually increased with the light irradiation period. The initial conidial release occurred between 2 to 4 h; the number of conidia remaining on the conidiophores gradually decreased and, eventually, the conidiophore lengths became shorter. In contrast, under blue light, few conidia were collected at any given time; the number of conidia on the conidiophores gradually increased and, eventually, the conidiophore lengths became longer. Next, the effects of red and blue light on the spread of powdery mildew infection by placing a KMP-6N-infected melon seedling at the centre of a tray containing healthy melon seedlings were examined. Almost all healthy seedlings caused powdery mildew symptoms at ca. 21 days after red light irradiation, whereas only healthy seedlings near the infected seedlings showed symptoms after blue light irradiation. Thus, the spread of melon powdery mildew infection clearly differed between red and blue light irradiation. This is the first report describing the effects of red and blue light on the spread of P. xanthii infection from a single infected seedling to healthy host seedlings; their results provide insight into the ecological mechanisms of powdery mildew conidial scatter from conidiophores.

Comparison of red light and blue light therapies for mild-to-moderate acne vulgaris: A randomized controlled clinical study.

Red and blue light therapies are safe and effective treatments for mild-to-moderate acne vulgaris. However, very few previous studies have directly compared the characteristics of these two methods. To compare the efficacy and side effects of red light (RL) and blue light (BL) for acne vulgaris and to assess these two therapies in different types of lesions. A total of 28subjects with mild-to-moderate acne vulgaris were randomized into the RL group or the BL group. Subjects in each group received different light treatments, and they were followed up regularly until 2weeks after the last treatment. The improvement rates of different types of acne lesions were compared between the 2groups, as well as the incidence of adverse reactions. At the 2-week follow-up, the average improvement rate of total acne lesions was 36.2% in the RL group and 30.7% in the BL group (p>.05). The average improvement rate of inflammatory and non-inflammatory lesions was 51.5% and 17.3% in the RL group, compared with 26.4% and 10.0% in the BL group (all p>.05). Treatment-related adverse reactions were observed distinctly in the BL group. Red light and BL therapies have similar efficacy in mild-to-moderate acne vulgaris, especially for inflammatory lesions. RL had advantages with fewer adverse reactions compared with BL.

Photo-induced visual response of western flower thrips attracted and repulsed by their phobotaxis spectrum light

This study aimed to clarify the synergistic phototactic attraction-repulsion effect formed by the photo-induced approach-avoidance behavior of thrips, construct phototactic attraction-repulsion light control technologies. The phototactic push-pull effects of red light and UV (365 nm), violet (405 nm), green (520 nm), and yellow (560 nm) single light, as well as their pairwise combined light on the behavior of western flower thrips were investigated using an apparatus that measured thrips response. The study also analyzed the influence of light properties on the phototactic attraction-repulsion effects of thrips and the synergistic effects of red light, and the attraction-repulsion regulation mode. The influence factors on the photo-induced attraction-repulsion effect of thrips were also discussed. The results showed that the red light, presenting the push effect, drove thrips to respond to the sensitive light. The synergistic attraction-repulsion effect of red light and single light, as well as that of red light and combined light was related to the light intensity. However, the attraction-repulsion synergism did not reflect thrips response effect and approach effect pulled and pushed by red light and single light, red light and combined light. Thrips preference for green-yellow light, and their behavior depended on the degree of UV light, making the attraction-repulsion synergy of red and green light the strongest. When the light intensity increased, the attraction-repulsion synergy of red and yellow light was the strongest. The attraction-repulsion response to red light and single light was related to the spectral attribute of the single light, with that of red light and UV light being better. The attraction-repulsion response to red light and combined light was related to light intensity. The intensity of combined light made the attraction-repulsion response to red light and the combined UV and violet light be the best, and the brightness of long-short spectrum light rendered red light and the combined UV and yellow light the best. All such light and combinations were remarkably better than that of red light and UV light. Relative to red light and UV light, the use red light and combined light provided limited enhancement to the approach effect of thrips; however, under red light and combined light, violet light intensified the approach of thrips to UV light, with yellow light strengthening the approach to green light. Those results provided a scientific basis for the development of light trapping equipment and the adjustment of light control strategies for thrips. Keywords: Western flower thrips, photo-induced visual response effect, attraction-repulsion effect, phobotaxis spectrum light, light intensity DOI: 10.25165/j.ijabe.20221502.7049 Citation: Liu Q H, Wu Y Q, Zhao M F. Photo-induced visual response of western flower thrips attracted and repulsed by their phobotaxis spectrum light. Int J Agric & Biol Eng, 2022; 15(2): 48–57.

The effect of storage and different red and far red light treatments on Catalpa ovata g. don seed germination

Chinese catalpa is a medicinal and ornamental, low demanding tree which tolerates urban pollution, drought and poor soils. It should be planted more often in Serbia, and gen?erative propagation is the most suitable method for mass production of this species. The aim of this research was to investigate the effects of red and far-red light on Catalpa ovata seed germination, as well as the influence of seed storage length on germination. The seeds were collected in 2003 and 2007 from the same tree, stored for one and five years and exposed to red light (R) or far-red light (FR) before seed germination tests. After one year of storage, seed germination was high (74-82%) in a control treatment (white light conditions, 16h light and 8h dark), and the seeds did not germinate in dark conditions. Red light and a combination of red light and far red light treatments induced germination, but the obtained values varied (7 - 66%) depending on the year of seed harvesting. The seeds collected in 2003 had a higher germination percentage (51.0%) compared to the germination of seeds collected in 2007 (up to 14%) after red light treatment. The time of exposure to red light pulse (10, 15, 20 or 30 min) did not considerably affect germination rate. After 5 years of storage, germination percentage was considerably lower, reaching only 30% in white light conditions. The results obtained in this research confirmed that C. ovata seeds are photoblastic and can be stored for one year preserving a high germination rate.

A novel approach to treating erectile dysfunction with a light-controlled nitric oxide donor

It has long been known that nitric oxide (NO) is involved in the initiation and maintenance of erection. For this reason, NO supplementation has been considered a useful target for the treatment of erectile dysfunction (ED), and many studies have been conducted. However, to date, no compounds have been launched for a variety of reasons. One of the reasons is the systemic adverse reactions. In order to solve this problem, we focused on light-controlled NO donors and investigate their potential application in ED treatment. Light-controlled NO donors have three main characteristics: first, they release NO only at the site of light irradiation, second, they release NO only during the time of light irradiation, and third, the amount of NO released can be controlled according to the light intensity. These features suggest that light-responsive NO donors may be useful for ED therapy. Our group has been working on the development of light-controlled NO donors, and has so far developed the blue light-controlled NO donor "NOBL-1", the yellowish-green light-controlled NO donor "NO-Rosa", and the red light-controlled NO donor "NORD-1". Our recent studies have shown that NORD-1 and red light can enhance the erectile response in rats at the in vivo level. Next, we examined the effects of NORD-1 and red light using a neurogenic ED model, which is believed to be less effective than existing ED drugs. The results showed that red light irradiation after NORD-1 administration enhanced the erectile response and improved ED in the neurogenic ED model. These results suggest that NORD-1, a light-controlled NO donor, and red light can enhance the erectile response in rats and may have potential as an ED drug. Although optimization of the compound is essential, it is expected that a new therapeutic approach called photobiotherapy for ED will be developed in the future.

Synergistic Effects of Photobiomodulation Therapy with Combined Wavelength on Diabetic Wound Healing In Vitro and In Vivo.

Objective: The difficulty in chronic diabetic wound healing remains the focus of clinical research. Photobiomodulation therapy (PBMT) with different wavelengths could exert different effects on wound healing, but the effects of combined red and blue light (BL) remained unclear. Methods: Diabetic rat wound model and diabetic wounded endothelial cell model were established to observe possible effects of PBMT using combined wavelengths for wound healing. Cells and animals were separated into four groups exposed to red and/or BL. Cell viability, apoptosis, and migration, as well as the expression level of nitric oxide (NO), vascular endothelial growth factor, interleukin-6, and tumor necrosis factor-α were measured in vitro. Diabetic rats were evaluated for wound closure rates, collagen deposition, inflammation intensity, and density of neovascularization after light irradiation. Results: PBMT using combined wavelengths significantly sped up the healing process with increasing angiogenesis density, collagen deposition, and alleviating inflammation in vivo. Moreover, combined wavelength irradiation promoted cell proliferation and migration, and NO production, as well as reduced reactive oxygen species and inflammation in vitro. Conclusions: PBMT using combined wavelengths performed a synergistic effect for promoting diabetic wound healing and would be helpful to explore a more efficient pattern toward chronic wound healing.

Blue-light treatment reduces spontaneous and evoked pain in a human experimental pain model.

Chronic pain is a frequent severe disease and often associated with anxiety, depression, insomnia, disability, and reduced quality of life. This maladaptive condition is further characterized by sensory loss, hyperalgesia, and allodynia. Blue light has been hypothesized to modulate sensory neurons and thereby influence nociception. Here, we compared the effects of blue light vs red light and thermal control on pain sensation in a human experimental pain model. Pain, hyperalgesia, and allodynia were induced in 30 healthy volunteers through high-density transcutaneous electrical stimulation. Subsequently, blue light, red light, or thermal control treatment was applied in a cross-over design. The nonvisual effects of the respective light treatments were examined using a well-established quantitative sensory testing protocol. Somatosensory parameters as well as pain intensity and quality were scored. Blue light substantially reduced spontaneous pain as assessed by numeric rating scale pain scoring. Similarly, pain quality was significantly altered as assessed by the German counterpart of the McGill Pain Questionnaire. Furthermore, blue light showed antihyperalgesic, antiallodynic, and antihypesthesic effects in contrast to red light or thermal control treatment. Blue-light phototherapy ameliorates pain intensity and quality in a human experimental pain model and reveals antihyperalgesic, antiallodynic, and antihypesthesic effects. Therefore, blue-light phototherapy may be a novel approach to treat pain in multiple conditions.

Effects of visible light on mechanisms of skin photoaging.

Human skin is not only affected by ultraviolet radiation but also by visible light wavelengths emitted by sunlight, electronic devices, and light emitting diodes. Similar to the ultraviolet radiation, visible light has been implicated in photoaging. In this review, the effects of blue light, yellow light, red light, and broad visible light are discussed in relation with photoaging. Different visible light wavelengths likely contribute beneficial and deleterious effects on photoaging by way of interaction with specific photoreceptors, ROS production, and other photon-mediated reactions. Further in vivo studies are needed to determine the mechanism and action spectrum of photoaging in humans, as well as optimal photoprotection with coverage against visible light wavelengths.

Macrophages Modulated by Red/NIR Light: Phagocytosis, Cytokines, Mitochondrial Activity, Ca2+ Influx, Membrane Depolarization and Viability.

Low-level light therapy (LLLT) is emerging as a promising therapeutic approach to modulate the biochemical and molecular processes within living cells. LLLT is known to produce local and systemic effects; therefore, immune cells in local tissues or in the circulation are affected by light. However, this specific effect remains weakly explored. In this study, the effect of red (650 nm) and NIR (808 nm) light on phagocytosis (respiratory burst), cytokine expression, mitochondrial activity, ROS generation, Ca2+ influx and membrane depolarization in macrophages invitro is investigated. Both the phagocytic capacity and adhesion of macrophages strongly (~2.5 times) increased in the first hours after exposure to light in a dose-dependent manner. The light-evoked upregulation of phagocytosis is found to be less efficient than the maximal pharmacologically induced enhancement of ~3.2 times. Also, red/NIR light reduces the production of pro-inflammatory cytokines and activates the secretion of anti-inflammatory cytokines by several times in activated macrophages. At the same time, the viability shows a biphasic dose response: it increases after irradiation with lower doses (0.3-1 J cm-2 ) and decreases after treatment with higher doses (18-30 J cm-2 ), which is apparently associated with the upregulation of ROS generation, followed by an increase in the mitochondrial activity.

Prenatal effects of red and blue light on physiological and behavioural parameters of broiler chickens

Light during incubation can influence embryonic and postembryonic development of chickens, but the underlying mechanisms are poorly understood. Previous studies have demonstrated that red and blue lights during incubation had opposite effects on the development of embryonic melatonin biosynthesis; red light results in the highest and blue light in the lowest amplitude of the daily rhythm. Therefore, in this study, we investigated if exposure to monochromatic red (632 nm) and blue (463 nm) light during incubation can differently influence growth, selected biochemical (glucose, cholesterol, triacylglycerols) and endocrine (corticosterone and thyroid hormones) traits and behavioural parameters during postembryonic development in broiler chickens. For analysis, we used 10 and 11 hatchlings incubated in red and blue light, respectively and 10 birds per each group (six males and four females) in 3-weeks-old broilers. During the rapid growth phase (days 18, 20 and 21 of age), higher body weight was recorded in broilers incubated under red compared to blue light, whereas endocrine and metabolic traits did not differ between the treatments. The improved growth rate was related to behavioural traits, mainly because chickens incubated in red light exhibited more passive (resting, standing, preening, dust bathing) and less active behaviours (walking, foraging, fighting, wing-flapping) than the blue-light incubated birds. The time spent for eating and drinking and the results of the tonic immobility test did not differ between both groups. Our results suggest that red and blue monochromatic light during incubation can differently program the postembryonic development of broilers, with possible consequences for their growth and welfare.

Effects of UV radiation on transcript and metabolite accumulation are dependent on monochromatic light background in cucumber.

During recent years, we have advanced our understanding of plant molecular responses to ultraviolet radiation (UV, 280-400 nm); however, how plants respond to UV radiation under different spectral light qualities is poorly understood. In this study, cucumber plants (Cucumis sativus "Lausanna RZ F1") were grown under monochromatic blue, green, red, and broadband white light in combination with UV radiation. The effects of light quality and UV radiation on acclimatory responses were assessed by measuring transcript accumulation of ELONGATED HYPOCOTYL 5 (HY5), CHALCONE SYNTHASE 2 (CHS2), and LIGHT HARVESTING COMPLEX II (LHCII), and the accumulation of flavonoids and hydroxycinnamic acids in the leaves. The growth light backgrounds differentially regulated gene expression and metabolite accumulation. While HY5 and CHS2 transcripts were induced by blue and white light, LHCII was induced by white and red light. Furthermore, UV radiation antagonized the effects of blue, red, green, and white light on transcript accumulation in a gene-dependent manner. Plants grown under blue light with supplementary UV radiation increased phenylalanine, flavonol disaccharide I and caffeic acid contents compared to those exposed only to blue light. UV radiation also induced the accumulation of flavonol disaccharide I and II, ferulic acid hexose and coumaric acid hexose in plants grown under green light. Our findings provide a further understanding of plant responses to UV radiation in combination with different light spectra and contribute to the design of light recipes for horticultural practices that aim to modify plant metabolism and ultimately improve crop quality.

Transcriptome analysis reveals effects of red and blue light-emitting 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 (Fv/Fm), photochemical quantum yield (ϕPSII), photochemical quenching (qp) 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.

Effects of White and Red Light Photoperiods on Physiology and Biochemistry as well as Glucoraphanin Metabololism of Broccoli Sprouts

In this study, the effects of white light and red light at different photoperiods (0, 4, 8, 12, 16 and 20 h·d−1) on growth, contents of soluble sugar, soluble protein, ascorbic acid, anthocyanins as well as glucoraphanin metabolism of broccoli sprouts were studied. The results showed that the growth of broccoli sprouts was inhibited by light treatment, but red light promoted the growth compared with white light. With the increasing of light photoperiods, the content of soluble sugar, soluble protein, ascorbic acid, glucoraphanin and total glucosinolates, myrosinase activity as well as sulforaphane formation firstly increased, then decreased. Compared with white light, red light significantly enhanced soluble sugar, soluble protein, ascorbic acid and glucoraphanin content in broccoli sprouts. However, higher anthocyanin content was observed in white light treated broccoli sprouts rather than red light treated broccoli sprouts. In addition, when photoperiod was less than 12 h, red light resulted in higher sulforaphane formation than white light (P<0.05). When photoperiod was more than 12 h, red light did not affect even decreased sulforaphane formation compared with white light treatment. In conclusion, red light treatment was beneficial to the enhancement of yield and nutritional quality of broccoli sprouts compared with white light, and 12 h·d−1 was the appropriate photoperiods.

Effect of red light on the composition of metabolites in tea leaves during the withering process using untargeted metabolomics.

Red light withering significantly improves the sensory flavor qualities of tea, although changes in metabolites during this process have not been systematically studied until now. The present study comprehensively analyzes metabolites in withered tea leaves at 2-h intervals up to 12 h under red light (630 nm) and dark conditions using ultra performance liquid chromatography-high resolution mass spectrometry (untargeted metabolomics). Ninety-four non-volatile compounds are identified and relatively quantified, including amino acids, catechins, dimeric catechins, flavonol glycosides, glycosidically-bound volatiles, phenolic acids and nucleosides. The results show that amino acids, catechins and dimeric catechins are most affected by red light treatment. Ten free amino acids, theaflavins and theasinensin A increase after red light irradiation, whereas epigallocatechin gallate and catechin fall. The present study provides a comprehensive and systematic profile of the dynamic effects of red light on withering tea and a rationale for its use in tea processing quality control. © 2021 Society of Chemical Industry.