Effects of Light-Emitting Diodes on the Accumulation of Phenolic Compounds and Glucosinolates in Brassica juncea Sprouts

Combination of light quality and melatonin regulates the quality in mustard sprouts

Mustard sprouts is a new form of vegetable product that is gaining attention due to its high content of health-promoting compounds such as glucosinolates. This study investigated the effects of different light qualities (white, red, and blue) alone and in combination with 100 μmol L-1 melatonin on the growth and health-promoting substance content of mustard sprouts. The results showed that white light + melatonin treatment promoted the accumulation of glucosinolates in sprouts (compared with white light increased by 47.89%). The edible fresh weight of sprouts treated with red light + melatonin was the highest, followed by white light + melatonin treatment. In addition, the sprouts treated with blue light + melatonin contained more ascorbic acid, flavonoids, and total phenolics. Therefore, the combined treatment of light quality (especially white light) and melatonin can provide a new strategy to improve the quality of mustard sprouts.

Effect of LED Lights on Secondary Metabolites and Antioxidant Activities in Red Pakchoi Baby Leaves

Pakchoi (Brassica rapa subsp. chinensis) is one of the most widely consumed vegetables in Asian countries, and it is high in secondary metabolites. The availability, quantity, and quality of light play a critical role in the growth and development of plants. In this study, we investigated the effect of LEDs (light-emitting diodes; white, blue, red, and red + blue) on anthocyanin, glucosinolates, and phenolic levels in red pakchoi baby leaves. On the 24th day after sowing (DAS), red baby pakchoi leaves were harvested, and shoot length, root length, and fresh weight were measured. Among the different LED treatments, there was no significant difference in shoot length, whereas the highest root length was achieved in the red + blue LED treatment (23.8 cm). The fresh weight also showed a significant difference among the different LED treatments. In total, 12 phenolic and 7 glucosinolate individual compounds were identified using high-performance liquid chromatography (HPLC) analysis. The highest total glucosinolate (2937 μg/g dry wt) and phenolic (1589 μg/g dry wt) contents were achieved in baby leaves exposed to red + blue light. Similarly, the highest contents of total anthocyanins (1726 μg/g dry wt), flavonoids (4920 μg/g dry wt), and phenolics (5900 μg/g dry wt) were achieved in the red + blue treatment. Plants exposed to red + blue LED light showed the highest accumulation of anthocyanin, glucosinolates, and phenolic compounds. For antioxidant activity, DPPH (2,2-diphenyl-1-picrylhydrazylradical) free radical scavenging, ABTS (2,2-azinobis (3-ethylbenzothiazoline)-6-sulfonic acid) radical scavenging, and reducing power assays were performed, and the antioxidant activity of red pakchoi baby leaves grown under red + blue LED light was found to be the best. The metabolic profiling of the identified metabolites revealed distinct separation based on the secondary metabolites. This research will be helpful for farmers to choose the best LED light combination to increase the secondary metabolic content in pakchoi plants.

Glucoraphanin Accumulation via Glucoraphanin Synthesis Promotion during Broccoli Germination

Glucoraphanin is an important glucosinolate which is widely distributed in Brassica vegetables and poses an anticancer effect to humans. Although researchers have paid a lot of attention to the changes in glucoraphanin concentration in seedlings of broccoli over 1-2 weeks, there has been little research focusing on the total whole-sprout glucoraphanin content within broccoli seedlings over 1-5 weeks. However, it is necessary to clarify the changes in total glucoraphanin content during the broccoli sprouting stage as broccoli seedlings are novel plant foods. This research explored glucoraphanin absolute accumulation and the biosynthesis mechanism in broccoli seedlings during a 5-week growth period. The results showed that glucoraphanin accumulation content was higher at week 4 than in the seeds. Moreover, the relative DL-methionine contents increased significantly after 3 weeks. Glucoraphanin synthetic gene expression levels were increased after 3 weeks, but the gene expressions of AOP3 (encoding 2-oxoglutarate-dependent dioxygenases) and MYR (encoding myrosinase) were significantly decreased. Furthermore, the 20 essential DEGs obtained can provide new insight into understanding the developmental regulation of broccoli seedlings. In addition, the results can also provide information on how to obtain higher glucoraphanin contents in broccoli sprouts.

Metabolite profiles and biological activities of different phenotypes of Chinese cabbage (Brassica rapa ssp. Pekinensis)

Chinese cabbage is considered as one of the most important cruciferous vegetables in South Korea because of its use in salads, kimchi, and Korean cuisine. Secondary metabolites were quantified in three Chinese cabbage varieties: 65065, interspecific hybrid of Chinese cabbage × red cabbage exhibiting a deep purple color; 85772, interspecific hybrid of Chinese cabbage × red mustard exhibiting a reddish-purple color; and a typical Chinese green cabbage cultivar "CR Carotene" (Brassica rapa subsp. pekinensis cv. CR Carotene). A total of 54 metabolites (2 amines, 2 sugar alcohols, 2 sugar phosphates, 6 carbohydrates, 18 amino acids, 13 organic acids, 8 phenolic compounds, and 3 carotenoids) were detected in 85772. Of them, 52 metabolites excluding β-carotene and 9-cis-β-carotene, and 51 metabolites excluding leucine, β-carotene, and 9-cis-β-carotene, were detected in 65065 and CR Carotene, respectively. Amino acid content was the highest in 85772, followed by 65065 and CR Carotene. The cultivars 65065 and 85772 contained high levels of phenolic compounds and total anthocyanins. Cyanidin-, pelargonidin-, and petunidin-type anthocyanins were detected in 65065 and 85772. However, delphinidin-type anthocyanins which typically impart a deep purple color were identified only in the deep purple phenotype 65065. Furthermore, the total anthocyanin content was the highest in 85772 (4.38 ± 0.65 mg g -1 dry weight) followed by that in 65065 (3.72 ± 0.52 mg g-1 dry weight). Antibacterial and antioxidant analyses revealed remarkable antibacterial effects of the purple cultivars against pathogens Vibrio parahaemolyticus (KCTC 2471), Bacillus cereus (KCTC 3624), Pseudomonas aeruginosa (KCCM 11803), Staphylococcus aureus (KCTC 3881), Chryseobacterium gleum (KCTC 2094), and Proteus mirabilis (KCTC 2510)] and methicillin-resistant pathogenic strains of Pseudomonas aeruginosa (0826, 0225, 0254, 1113, 1378, 1731, p01827, and p01828) compared with the antibacterial effects of CR Carotene. Furthermore, 65065 and 85772 exhibited significantly higher antioxidant activity than that of the CR Carotene. Therefore, the novel purple Chinese cabbages (65065 and 85772), derived from interspecific hybridization, are potentially favorable alternatives to the typical green Chinese cabbage, given the higher content of amino acids, phenolic compounds, anthocyanins, and carotenoids, as well as an increased ability to scavenge free radicals and inhibit pathogen growth.

LED Lights Influenced Phytochemical Contents and Biological Activities in Kale (Brassica oleracea L. var. acephala) Microgreens

Light-emitting diodes (LEDs) are regarded as an effective artificial light source for producing sprouts, microgreens, and baby leaves. Thus, this study aimed to investigate the influence of different LED lights (white, red, and blue) on the biosynthesis of secondary metabolites (glucosinolates, carotenoids, and phenolics) and the biological effects on kale microgreens. Microgreens irradiated with white LEDs showed higher levels of carotenoids, including lutein, 13-cis-β-carotene, α-carotene, β-carotene, and 9-cis-β-carotene, than those irradiated with red or blue LEDs. These findings were consistent with higher expression levels of carotenoid biosynthetic genes (BoPDS and BoZDS) in white-irradiated kale microgreens. Similarly, microgreens irradiated with white and blue LEDs showed slightly higher levels of glucosinolates, including glucoiberin, progoitrin, sinigrin, and glucobrassicanapin, than those irradiated with red LEDs. These results agree with the high expression levels of BoMYB28-2, BoMYB28-3, and BoMYB29 in white- and blue-irradiated kale microgreens. In contrast, kale microgreens irradiated with blue LEDs contained higher levels of phenolic compounds (gallic acid, catechin, ferulic acid, sinapic acid, and quercetin). According to the total phenolic content (TPC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition assays, the extracts of kale microgreens irradiated with blue LEDs had slightly higher antioxidant activities, and the DPPH inhibition percentage had a positive correlation with TPC in the microgreens. Furthermore, the extracts of kale microgreens irradiated with blue LEDs exhibited stronger antibacterial properties against normal pathogens and multidrug-resistant pathogens than those irradiated with white and red LEDs. These results indicate that white-LED lights are suitable for carotenoid production, whereas blue-LED lights are efficient in increasing the accumulation of phenolics and their biological activities in kale microgreens.

Effect of Sprouting on the Phenolic Compounds, Glucosinolates, and Antioxidant Activity of Five Camelina sativa (L.) Crantz Cultivars

Sprouts are increasingly present in the human diet, being tasty and healthy foods high in antioxidant compounds. Although there is a body of literature on the sprouting of many plant species, Camelina sativa (L.) Crantz has not yet been studied for this purpose. This study aimed to characterize the main bioactive compounds and antioxidant potential of seeds and sprouts of five different Camelina cultivars (ALBA, CO46, CCE43, JOELLE, and VERA). In particular, the contents of phenolic compounds (PCs), phenolic acids (PAs), and glucosinolates (GLSs) were investigated. PCs, PAs, GLSs, and the antioxidant activity of seeds differed among cultivars and were greatly increased by sprouting. A PCA analysis underlined both the effect of the cultivar (PC2) and the germination (PC1) on the nutritional properties of Camelina. The best nutritional properties of seeds were observed for ALBA and CCE43, while the best nutritional properties of sprouts were recorded for CCE43 and JOELLE, since the latter cultivar showed a greater enhancement in phytochemical content and antioxidant activity with sprouting. Finally, a UHPLC-UV procedure for the analysis of GLSs in Camelina was developed and validated. The performance criteria of the proposed method demonstrated that it is useful for the analysis of GLSs in Camelina.

Metabolic Profiling of Primary and Secondary Metabolites in Kohlrabi (Brassica oleracea var. gongylodes) Sprouts Exposed to Different Light-Emitting Diodes

Light-emitting diode (LED) technology is one of the most important light sources in the plant industry for enhancing growth and specific metabolites in plants. In this study, we analyzed the growth, primary and secondary metabolites of 10 days old kohlrabi (Brassica oleracea var. gongylodes) sprouts exposed to different LED light conditions. The results showed that the highest fresh weight was achieved under red LED light, whereas the highest shoot and root lengths were recorded below the blue LED light. Furthermore, high-performance liquid chromatography (HPLC) analysis revealed the presence of 13 phenylpropanoid compounds, 8 glucosinolates (GSLs), and 5 different carotenoids. The phenylpropanoid and GSL contents were highest under blue LED light. In contrast, the carotenoid content was found to be maximum beneath white LED light. Principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) of the 71 identified metabolites using HPLC and gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS) showed a clear separation, indicating that different LEDs exhibited variation in the accumulation of primary and secondary metabolites. A heat map and hierarchical clustering analysis revealed that blue LED light accumulated the highest amount of primary and secondary metabolites. Overall, our results demonstrate that exposure of kohlrabi sprouts to blue LED light is the most suitable condition for the highest growth and is effective in increasing the phenylpropanoid and GSL content, whereas white light might be used to enhance carotenoid compounds in kohlrabi sprouts.

Chickpea and Lupin Sprouts, Stimulated by Different LED Lights, As Novel Examples of Isoflavones-Rich Functional Food, and Their Impact on Breast and Prostate Cells

Among all legumes sprouts' active compounds, isoflavones seem to be the most important; nevertheless, their high content is not always associated with beneficial effects. These compounds may prevent or stimulate hormone-dependent cancers due to their estrogen-like activity. Different LED light quality can change the synthesis of active compounds and significantly influence the biological activity of the sprouts. This study aimed to evaluate the effects of LED light (red, blue, green, yellow), as well as total darkness, and natural light conditions (as reference), on isoflavones content, determined by HPLC-UV-VIS, during 10 days of harvesting of chickpea and lupin sprouts. Due to the ambiguous estrogenic potential of isoflavones, the impact of these sprouts on normal and cancer prostate and breast cells was evaluated. Yellow LED light resulted in the highest sum of isoflavones in chickpea sprouts (up to 1 g/100 g dw), while for green LED light, the isoflavones sum was the lowest. The exact opposite effect was noted for lupin sprouts, with the predominance of green over the yellow LED light. The examined sprouts were of high safety to non-neoplastic breast and prostate cells, with interesting cytotoxic effects on breast MCF7 and prostate DU145 cancer cells. No clear relationship was observed between the activity and isoflavones content.

The Combination of Monochromatic LEDs and Elicitation with Stressors Enhances the Accumulation of Glucosinolates in Mustard Sprouts with Species-Dependency

This work studies the enhancement of glucosinolates (GSLs) in mustard sprouts as health promoters. Sprouts of Sinapis alba, Brassica nigra, and B. carinata were grown under broad-spectrum, monochromatic blue or red light-emitting diode (LED) lamps, irrigated with 0-100 mM sodium chloride (NaCl), and sprayed with 0-250 µM methyl jasmonate (MeJA) as elicitor. The use of LEDs did not result in increased sprout biomass in any case. The effect of the applied treatments on the GSLs depended on the species and were restricted to Brassica spp. The red LEDs produced an overall increase in GSLs over 500% in B. carinata (from 12 to 81 mg 100 g^-1 F.W.), compared to the white broad-spectrum lights, although the highest increase in content was obtained in treated sprouts with 250 µM MeJA (104 an 105 mg 101 g^-1 F.W., under the red and blue LEDs, respectively). The combination of blue LEDs, 100 mM NaCl, and 250 µM MeJA enhanced the levels of GLSs in B. nigra to the maximum (81 mg 100 g^-1 F.W.). Overall, these results indicate that by modifying the growing conditions for a given sprout, enhancement in the accumulation of GSLs as health promoters is possible. The use of these treatments is a sustainable alternative to genetic modification when looking for bioactive-enriched foods, delivering natural plant foods rich in bioactive ingredients (e.g., glucosinolates). Nevertheless, the response to the treatments varies among species, indicating that treatments will require adjustment across sprouts. Further research continues with producing cruciferous sprouts to obtain GSL-enriched formulas for further studying the effects of their bioavailability and bioactivity on health-promotion.

A study on the proliferation of Myzus persicae (sulzer) during the winter season for year-round production within a smart farm facility

In this study, we examined the feasibility of Myzus persicae proliferation through interrelationships with host plants in a smart farm facility during winter. We investigated aphid proliferation under an LED artificial light source and attempted to interpret aphid proliferation in relation to the net photosynthetic rate of the host plant, Eutrema japonicum. We observed that aphids continuously proliferated in the smart farm facility in winter without dormancy. The average number of aphids was greater under the 1:1 red:blue light irradiation time ratio, where the photosynthetic rate of the host plant was lower than under the 5:1 and 10:1 red:blue light irradiation time ratios. These results show that it is important to maintain a low net photosynthetic rate of the host plant, E. japonicum, in order to effectively proliferate aphids under artificial light such as in the case of smart farm facilities.

Isolation of bioactive peptides and multiple nutraceuticals of antidiabetic and antioxidant functionalities through sprouting: Recent advances

The employment of proteases directly from enzymes or indirectly from microorganisms during fermentation for the purpose of proteolysis of food proteins has been the conventional trend for the derivation of bioactive peptides from food matrices. However, recent studies have shown that inherent protease enzymes can be activated for this activity for vegetable foods using the sprouting process. The benefits of ease of operation, and reduced processing costs are formidable advantages for the optimal consideration of this technique. On another note, the demand for functional foods with therapeutic health effects has increased in recent years. Globally, plant foods are perceived as dietetic choices bearing sufficient quantities of concomitant nutraceuticals. In this manuscript, the sprouting route for the isolation of peptides and glucosinolates, and for the enhancement of total phenolic contents, polyunsaturated fatty acid profiles, and other bioactive constituents was explored. Advances regarding the phytochemical transformations in the course of sprouting, the therapeutic functionalities, and microbiological safety concerns of vegetable sprouts are delineated. In addition, consumption of vegetable sprouts has been shown to be more efficient in supplying nutraceutical components relative to their unsprouted counterparts. Biochemical mechanisms involving the inhibition of digestive enzymes such as α-amylase, β-glucosidase, and dipeptidyl peptidase IV (DPP-IV), single electron transfer, and metal chelation, for impartation of health benefits, have been reported to occur from bioactive components isolated from vegetable sprouts. PRACTICAL APPLICATIONS: Sprouting initiates proteolysis of vegetable proteins for the release of bioactive peptides. Abiotic stresses can be used as elicitors during the sprouting process to achieve enhanced phytochemical profiles of sprouts. Sprouting is a relatively more convenient approach to the improvement of the health benefits of vegetable foods. Vegetable sprouts are potential for the management of metabolic syndrome disorders.

Supplemental UV-B Exposure Influences the Biomass and the Content of Bioactive Compounds in Linum usitatissimum L. Sprouts and Microgreens

The interest in the pre-harvest ultraviolet-B (UV-B) exposure of crops in indoor cultivation has grown consistently, though very little is known about its influence on the nutraceutical quality of microgreens. Flaxseeds constitute a valuable oilseed species, mostly appreciated for their nutritional properties and the presence of health-promoting compounds. Therefore, although scarcely studied, flaxseed sprouts and microgreens might constitute a high-quality food product to be included in a healthy diet. This study aims to unravel the effects of pre-harvest ultraviolet-B irradiation on the nutritional and nutraceutical quality of flaxseed sprouts and microgreens grown under artificial conditions. The UV-B irradiation decreased the biomass and stem length of microgreens. However, the content of total phenolics and flavonoids and the antioxidant capacity were strongly enhanced by the UV-B treatment in both sprouts and microgreens. Among photosynthetic pigments, chlorophyll a, violaxanthin, antheraxanthin, and lutein in sprouts were reduced by the treatment, while chlorophyll b increased in microgreens. In conclusion, our results showed that growing flaxseed sprouts and microgreens in controlled conditions with supplemental UV-B exposure might increase their nutritional and nutraceutical quality, as well as their antioxidant capacity, making them high-quality functional foods.

Metabolite Characteristics Analysis of Siliques and Effects of Lights on the Accumulation of Glucosinolates in Siliques of Rapeseed

Glucosinolates (GSLs) are naturally occurring secondary metabolites found in the Brassicaceae family, which mainly synthesize in the siliques with a wide range of functions. In this study, we investigated the effects of lights on metabolites in siliques of rapeseed through ultra high-performance liquid chromatography (UPLC)-heated electrospray ionization (HESI)-tandem mass spectrometry (MS/MS). A total of 249 metabolites, including 29 phenolic acids, 38 flavonoids, 22 GSLs, 93 uncalculated and 67 unknown compounds, were identified in siliques of rapeseed. Meanwhile, 62 metabolites showed significant differences after shading treatment, which were mainly GSLs and unknown compounds. Interestingly, the amounts of 10 GSLs had high accumulation levels in siliques, while the expression levels of their corresponding biosynthetic genes (AOP, GSL-OH, IGMT, and ST5a) were obviously reduced after shading treatment. Further evidence showed that the amounts of GSLs were significantly reduced in seeds, in accordance with the expression profiles of transporter genes (BnaGTRs). Our findings indicated that lights could affect the accumulation and transportation of GSLs from siliques to seeds in rapeseed. Therefore, this study facilitates a better understanding of metabolic characteristics of siliques and provides insight into the importance of light for GSLs accumulation and transportation in siliques and seeds of rapeseed.

Effect of combined light-emitting diodes on the accumulation of glucosinolates in Brassica microgreens

As of recent, microgreen vegetable production in controlled environments are being investigated for their bioactive properties. Phytochemicals like glucosinolates (GLS) are highly sensitive to varying spectral qualities of light, especially in leafy greens of Brassica where the responses are highly species-dependent. The accumulation of bioactive GLS were studied under 8 different treatments of combined amber (590 nm), blue (455 nm), and red (655 nm) light-emitting diodes (rbaLED). A semi-targeted metabolomics approach was carried out to profile common intact-GLS in microgreen extracts of Brassica by means of LC-HRMS/MS. Thirteen GLS were identified, among them were 8 aliphatic, 4 indolic and 1 aromatic GLS. Mass spectrometry data showed sinigrin had the highest average concentration and was highest in B. juncea, progoitrin was highest in B. rapa and glucobrassicin in R. sativus. The individual and total GLS in the microgreens of the present study were largely different under rbaLED; B. rapa microgreens contained the highest profile of total GLS, followed by R. sativus and B. juncea. Sinigrin was increased and gluconasturtiin was decreased under rbaLED lighting in most microgreens, glucoalyssin uniquely increased in R. sativus and decreased in B. rapa and glucobrassicin uniquely decreased in both B. rapa and B. juncea. The present study showed that rbaLED contributed to the altered profiles of GLS resulting in their significant modulation. Optimizing the light spectrum for improved GLS biosynthesis could lead to production of microgreens with targeted health-promoting properties.

Graphical Abstract

Exposure to Salinity and Light Spectra Regulates Glucosinolates, Phenolics, and Antioxidant Capacity of Brassica carinata L. Microgreens

The effect of salt treatment on Brassica carinata (BC) microgreens grown under different light wavelengths on glucosinolates (GLs) and phenolic compounds were evaluated. Quantifiable GLs were identified using ultra-high performance-quadrupole time of flight mass spectrometry. Extracts' ability to activate antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)) was evaluated on human colorectal carcinoma cells (HCT116). Furthermore, BC compounds' ability to activate expression of nuclear transcription factor-erythroid 2 related factor (Nrf2) and heme-oxygenase-1 (HO-1) proteins was examined using specific antibodies on HCT116 cells. Sinigrin (SIN) was the abundant GLs of the six compounds identified and its content together with total aliphatic GLs increased in saline conditions. Fluorescent (FL) and blue plus red (B1R1) lights were identified as stable cultivation conditions for microgreens, promoting biomass and glucobrassicin contents, whereas other identified individual and total indole GLs behaved differently in saline and non-saline environments. Blue light-emitting diodes and FL light in saline treatments mostly enhanced SIN, phenolics and antioxidant activities. The increased SOD and CAT activities render the BC microgreens suitable for lowering oxidative stress. Additionally, activation of Nrf2, and HO-1 protein expression by the GLs rich extracts, demonstrate their potential to treat and prevent oxidative stress and inflammatory disorders. Therefore, effective salt treatments and light exposure to BC microgreens present an opportunity for targeted regulation of growth and accumulation of bioactive metabolites.

Anything New under the Sun? An Update on Modulation of Bioactive Compounds by Different Wavelengths in Agricultural Plants

Plants continuously rely on light as an energy source and as the driver of many processes in their lifetimes. The ability to perceive different light radiations involves several photoreceptors, which in turn activate complex signalling cascades that ultimately lead to a rearrangement in plant metabolism as an adaptation strategy towards specific light conditions. This review, after a brief summary of the structure and mode of action of the different photoreceptors, introduces the main classes of secondary metabolites and specifically focuses on the influence played by the different wavelengths on the content of these compounds in agricultural plants, because of their recognised roles as nutraceuticals.

Metabolic Analysis of Root, Stem, and Leaf of Scutellaria baicalensis Plantlets Treated with Different LED Lights

Light emitting diodes (LEDs) have recently been considered an efficient artificial light source in plant factories for enhancing plant growth and nutritional quality. Accordingly, this study aimed to review blue, red, and white LED light sources for efficiency and length of the growing period to produce seedlings of Scutellaria baicalensis with high nutritional value. The roots, stems, and leaves of S. baicalensis seedlings were grown under different LED lights and harvested after two and four weeks, and analyzed using high-performance liquid chromatography and gas chromatography time-of-flight mass spectrometry to identify and quantify primary and secondary metabolites. Roots, particularly in the seedlings treated with white LEDs were determined to contain the greatest concentrations of the representative compounds present in S. baicalensis: baicalin, baicalein, and wogonin, which show highly strong biological properties compared to the other plant organs. A total of 50 metabolites (amino acids, sugars, sugar alcohols, organic acids, phenolic acids, and amines) were detected in the roots, stems, and leaves of S. baicalensis seedlings, and the concentrations of primary and secondary metabolites were generally decreased with the increasing duration of LED illumination. Therefore, this study suggests that white LED light and a 2-week growing period are the most efficient conditions for the production of baicalin, baicalein, and wogonin.

Application of Light-Emitting Diodes for Improving the Nutritional Quality and Bioactive Compound Levels of Some Crops and Medicinal Plants

Light is a key factor that affects phytochemical synthesis and accumulation in plants. Due to limitations of the environment or cultivated land, there is an urgent need to develop indoor cultivation systems to obtain higher yields with increased phytochemical concentrations using convenient light sources. Light-emitting diodes (LEDs) have several advantages, including consumption of lesser power, longer half-life, higher efficacy, and wider variation in the spectral wavelength than traditional light sources; therefore, these devices are preferred for in vitro culture and indoor plant growth. Moreover, LED irradiation of seedlings enhances plant biomass, nutrient and secondary metabolite levels, and antioxidant properties. Specifically, red and blue LED irradiation exerts strong effects on photosynthesis, stomatal functioning, phototropism, photomorphogenesis, and photosynthetic pigment levels. Additionally, ex vitro plantlet development and acclimatization can be enhanced by regulating the spectral properties of LEDs. Applying an appropriate LED spectral wavelength significantly increases antioxidant enzyme activity in plants, thereby enhancing the cell defense system and providing protection from oxidative damage. Since different plant species respond differently to lighting in the cultivation environment, it is necessary to evaluate specific wavebands before large-scale LED application for controlled in vitro plant growth. This review focuses on the most recent advances and applications of LEDs for in vitro culture organogenesis. The mechanisms underlying the production of different phytochemicals, including phenolics, flavonoids, carotenoids, anthocyanins, and antioxidant enzymes, have also been discussed.