Effects of Darkness and Light Spectra on Nutrients and Pigments in Radish, Soybean, Mung Bean and Pumpkin Sprouts

Can Simulated Microgravity and Darkness Conditions Influence the Phytochemical Content and Bioactivity of the Sprouts?-A Preliminary Study on Selected Fabaceae Species

Sprouts' consumption has become popular due to their wide availability, easy cultivation process, and proven biological activity. Moreover, stress factors, such as limited access to light or disturbed gravity during growth, may contribute to the increased activity and the synthesis of bioactive compounds. In this study, for the first time, the examination of the impact of darkness and simulated microgravity conditions on the white clover sprouts from the Fabaceae family was conducted. Among several species, used in the preliminary attempts, only white clover was satisfactory sprouting in the disturbed gravity conditions, and thus was chosen for further examination. A random positioning machine setup was used during the cultivation process to simulate microgravity conditions. Additionally, the sprouts were cultivated in total darkness. Simulated microgravity and/or darkness during the first few days of the sprouts' growth caused biomass reduction, the increased synthesis of bioactive compounds (isoflavones and phenolics), and changes in the level of abscisic acid and phenylalanine ammonia-lyase. Moreover, it increased the antioxidant properties of the sprouts, while the enhancement of their cytotoxic impact was observed only for androgen-dependent prostate cancer LNCaP cells. To conclude, the presented results are promising in searching for novel functional food candidates and further studies are necessary, directed at other plant families.

GmMYB114 Facilitates the Synthesis of Anthocyanins in Soybean Sprouts under Blue Light

Soybean sprouts constitute a significant segment of the vegetable market due to their nutritional richness, particularly in various flavonoids, which contribute to numerous health benefits. The augmentation of the flavonoid content in soybean sprouts is pivotal for enhancing their economic value. While research has established the potential of blue light in promoting the synthesis of anthocyanins, a subclass of flavonoids known for their health advantages, the precise regulatory mechanisms remain elusive. In this study, we identified a notable upregulation of an R2R3 type MYB transcription factor, GmMYB114, in response to blue light exposure, exhibiting a significant positive correlation with anthocyanin accumulation in soybean sprouts. The functional role of GmMYB114 was validated in soybean hairy roots, wherein its overexpression substantially augmented anthocyanin synthesis. Further investigations employing yeast one-hybrid (Y1H), dual-luciferase reporter (LUC), and GUS assays revealed that GmMYB114 indirectly influences anthocyanin synthesis as it does not directly bind to the promoters of anthocyanin synthesis genes to activate their expression. These findings contribute to elucidating the mechanism underlying blue light-mediated enhancement of anthocyanin synthesis in soybean sprouts, offering valuable insights for harnessing molecular technologies to obtain anthocyanin-enriched soybean sprouts.

An Integrated Approach for Biofortification of Carotenoids in Cowpea for Human Nutrition and Health

Stress-resilient and highly nutritious legume crops can alleviate the burden of malnutrition and food security globally. Here, we focused on cowpea, a legume grain widely grown and consumed in regions at a high risk of micronutrient deficiencies, and we discussed the past and present research on carotenoid biosynthesis, highlighting different knowledge gaps and prospects for increasing this micronutrient in various edible parts of the crop. The literature survey revealed that, although carotenoids are important micronutrients for human health and nutrition, like in many other pulses, the potential of carotenoid biofortification in cowpea is still underexploited. We found that there is, to some extent, progress in the quantification of this micronutrient in cowpea; however, the diversity in content in the edible parts of the crop, namely, grains, pods, sprouts, and leaves, among the existing cowpea genetic resources was uncovered. Based on the description of the different factors that can influence carotenoid biosynthesis and accumulation in cowpea, we anticipated that an integrated use of omics in breeding coupled with mutagenesis and genetic engineering in a plant factory system would help to achieve a timely and efficient increase in carotenoid content in cowpea for use in the food systems in sub-Saharan Africa and South Asia.

Blue and Red LED Lights Differently Affect Growth Responses and Biochemical Parameters in Lentil (Lens culinaris)

Light-emitting diodes are an attractive tool for improving the yield and quality of plant products. This study investigated the effect of different light intensity and spectral composition on the growth, bioactive compound content, and antioxidant metabolism of lentil (Lens culinaris Medik.) seedlings after 3 and 5 days of LED treatment. Two monochromatic light quality × three light intensity treatments were tested: red light (RL) and blue light (BL) at photosynthetic photon flux density (PPFD) of 100, 300, and 500 μmol m-2 s-1. Both light quality and intensity did not affect germination. At both harvest times, the length of seedling growth under BL appeared to decrease, while RL stimulated the growth with an average increase of 26.7% and 62% compared to BL and seedlings grown in the darkness (D). A significant blue light effect was detected on ascorbate reduced form, with an average increase of 35% and 50% compared to RL-grown plantlets in the two days of harvesting, respectively. The content of chlorophyll and carotenoids largely varied according to the wavelength and intensity applied and the age of the seedlings. Lipid peroxidation increased with increasing light intensity in both treatments, and a strong H2O2 formation occurred in BL. These results suggest that red light can promote the elongation of lentil seedlings, while blue light enhances the bioactive compounds and the antioxidant responses.

The Effect of Illumination Patterns during Mung Bean Seed Germination on the Metabolite Composition of the Sprouts

Mung bean (Vigna radiata (L.) Wilczek) sprouts are popular over the world because of their taste, nutritional value, well-balanced biochemical composition, and other properties beneficial for human health. Germination conditions affect the composition of metabolites in mung bean sprouts, so a detailed study into its variability is required. This article presents the results of a comparison of the metabolite composition in the leaves of mung bean sprouts germinated first in the dark (DS) and then in the light (LS). Gas chromatography with mass spectrometry (GC-MS) made it possible to identify more than 100 compounds representing various groups of phytochemicals. Alcohols, amino acids, and saccharides predominated in the total amount of compounds. The analysis of metabolomic profiles exposed a fairly high intra- and intervarietal variability in the metabolite content. DS and LS differed in the qualitative and quantitative content of the identified compounds. The intravarietal variability was more pronounced in DS than in LS. DS demonstrated higher levels of saccharides, fatty acids, acylglycerols, and phenolic compounds, while amino acids were higher in LS. Changes were recorded in the quantitative content of metabolites participating in the response of plants to stressors-ornithine, proline, GABA, inositol derivatives, etc. The changes were probably induced by the stress experienced by the sprouts when they were transferred from shade to light. The analysis of variance and principal factor analysis showed the statistically significant effect of germination conditions on the content of individual compounds in leaves. The identified features of metabolite variability in mung bean genotypes grown under different conditions will contribute to more accurate selection of an illumination pattern to obtain sprouts with desirable biochemical compositions for use in various diets and products with high nutritional value.

The Effect of Light and Dark Treatment on the Production of Rosmarinic Acid and Biological Activities in Perilla frutescens Microgreens

This study aimed to investigate the effect of light [a long-day photoperiod (16 h light/8 h dark cycle)] and dark treatment on the production of rosmarinic acid in P. frutescens microgreens and to determine its antioxidant and antibacterial activities. Microgreens of P. frutescens were grown under light and dark conditions and harvested after 10, 15, 20, and 25 days of each treatment. Although dry weight values of microgreens gradually increased from 10 to 25 days of both treatments, the microgreens grown under light treatment possessed slightly higher levels of dry weight than those grown in the dark. Rosmarinic acid and total phenolic content (TPC) were also analyzed using high-performance liquid chromatography (HPLC) and Folin-Ciocalteu assay. The accumulation patterns of rosmarinic acid and TPC gradually increased and decreased, respectively, in P. frutescens microgreens grown in continuous darkness. The highest accumulation was observed in microgreens grown for 20 days. However, rosmarinic acid and TPC values were not significantly different in microgreens grown under light conditions. According to the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition assay, the extracts of P. frutescens microgreens were confirmed to be strong antioxidants, and their ability to scavenge DPPH radicals was positively correlated with the total phenolic content in the microgreens after 10, 15, 20, and 25 days of both treatments. Considering the relatively higher values of dry weight, rosmarinic acid, TPC, and DPPH assay, P. frutescens microgreens after 20 days of darkness and 20 days of light treatment, respectively, were selected for screening antibacterial activity using nine pathogens. Both microgreen extracts showed strong antibacterial activity against pathogens. In particular, the extracts of microgreens grown for 20 days under light treatment showed higher antimicrobial effects. Therefore, the light treatments for 20 days, as well as the darkness treatment for 20 days, were the best conditions for P. frutescens microgreen production because of their high levels of dry weight, phenolics, and biological activities.

Bioactive Compounds, Antioxidant Activities, and HPLC Analysis of Nine Edible Sprouts in Cambodia

The non-nutritional health benefits of sprouts are unconfirmed. Thus, nine sprout methanolic extracts were tested for phytoconstituents and antioxidant activity. The TPC, TCC, TFC, TAC, and TALC were measured. ABTS and DPPH radical scavenging and ferric-reducing antioxidant power assays were used to assess the antioxidant activity. HPLC detected gallic acid, vanillin, syringic acid, chlorogenic acid, caffeic acid, and rutin in the extracts. The sprout extracts contained six compounds, with caffeic acid being the most abundant. Gallic acid, syringic acid, chlorogenic acid, caffeic acid, vanillin, and rutin were highest in soybean, black sesame, mustard, sunflower, white radish, and black sesame sprouts, respectively. Sunflower sprouts had the highest level of TCC while soybean sprouts had the highest level of TFC, Taiwanese morning glory had the highest level of TPC, mustard sprouts had the highest level of TALC, and black sesame sprouts had the highest level of TAC. Taiwanese morning glories scavenged the most DPPH and ABTS radicals. Colored and white radish sprouts had similar ferric-reducing antioxidant power. Antioxidation mechanisms varied by compound. Our findings demonstrated that sprouts have biological effects, and their short time for mass production offers an alternative food source for health benefits, and that they are useful for future research development of natural products and dietary supplements.

Effect of light quality on polyphenol biosynthesis in three varieties of mung bean sprouts with different color seed coats

We investigated the mechanism of the effect of different light qualities on the synthesis and regulation of mung bean sprouts. Light quality acts as a signal molecule, strongly enhancing polyphenol biosynthesis in sprouts. Mung bean (Vigna radiata) sprouts are a popular sprouting vegetable all over the world and are an excellent source of polyphenols with high antioxidant activity. This study investigated the effects of light qualities on the kinetic changes and metabolic regulation mechanism of light signal-mediating polyphenols in three mung bean sprout cultivars. Experimental results showed that three light qualities significantly enhanced the contents of caffeic acid, rutin, vitexin, genistin and delphinidin 3-glucoside. Interestingly, ferulic acid and vitexin responded selectively to blue light and red light, severally. Most genes involved in polyphenol biosynthesis were activated under different light quality conditions, resulting in an overaccumulation of phenylpropanoids. Pearson correlation analysis showed that PAL, F3H, F3'H and F3'5'H expression correlated highly with rutin, whereas ANS expression paralleled anthocyanin biosynthesis. Moreover, MYB111, MYB3, MYB4, MYB1 and MYC2 were critical regulators of polyphenol biosynthesis in mung bean sprouts. These changes were likely due to the changes in the expression of the photoreceptor genes CRY-D, PHOT2, PHYE and light response genes (PIF3 and HY5). Our results provide insights into polyphenol biosynthesis in sprouts and microgreens.

Integrated metabolomic and transcriptomic analyses reveal molecular response of anthocyanins biosynthesis in perilla to light intensity

The perilla anthocyanins have important medicinal and ornamental value, and their contents are significantly affected by light intensity. In view of their molecular mechanisms were not well understood, we integrated the metabolomic and transcriptomic analyses of the light-sensitive perilla variety under different light intensity. The perilla leave color were obviously affected under different treatments. Totally 140 flavonoid metabolites and 2461 genes showed steady change, among which 60 flavonoid metabolites were increased accumulation and 983 genes were upregulated expression under elevated light intensity treatment. Light treatment prominently affected the expression of genes involved in the main anthocyanin metabolites accumulation in perilla leaves. Using WGCNA analysis, we identified 4 key genes in anthocyanin biosynthesis pathway (CHI, DFR, and ANS) and 147 transcription factors (MYB, bHLH, bZIP, ERF, and NAC) involved in malonylshisonin biosynthesis. Among them, 6 MYBs and 4 bZIPs were predicted to play important roles in light regulation of malonylshisonin biosynthesis based on phylogenetic construction, correlation analysis, cis-acting element identification and qPCR verification. The identified key genes and regulatory factors will help us to understand the potential mechanism of photo-regulated anthocyanin accumulation in perilla.

Comprehensive transcriptomic and metabolomic profiling reveals the differences between alfalfa sprouts germinated with or without light exposure

Alfalfa sprouts are among the most nutritionally rich foods, and light exposure is a critical factor in determining their biomass and quality. However, detailed metabolic and molecular differences between yellow and green alfalfa sprouts remain unclear. In this study, comprehensive metabolomic and transcriptomic analyses were integrated to evaluate the nutrient composition of alfalfa sprouts during germination with or without light exposure. Differentially expressed genes and differentially accumulated metabolites in green and yellow alfalfa sprouts were significantly enriched in secondary metabolic pathways, such as the isoflavonoid biosynthesis pathway. Green alfalfa sprouts contained a wide variety of lipids, flavonoids, phenolic acids, and terpenoids, among which the top three upregulated were calycosin, methyl gallate, and epicatechin 3-gallate, whereas yellow alfalfa sprouts contained relatively more isoquercitrin. These results provide new insights into the nutritional value and composition of alfalfa sprouts under different germination regimes.

Sprouts and Microgreens-Novel Food Sources for Healthy Diets

With the growing interest of society in healthy eating, the interest in fresh, ready-to-eat, functional food, such as microscale vegetables (sprouted seeds and microgreens), has been on the rise in recent years globally. This review briefly describes the crops commonly used for microscale vegetable production, highlights Brassica vegetables because of their health-promoting secondary metabolites (polyphenols, glucosinolates), and looks at consumer acceptance of sprouts and microgreens. Apart from the main crops used for microscale vegetable production, landraces, wild food plants, and crops' wild relatives often have high phytonutrient density and exciting flavors and tastes, thus providing the scope to widen the range of crops and species used for this purpose. Moreover, the nutritional value and content of phytochemicals often vary with plant growth and development within the same crop. Sprouted seeds and microgreens are often more nutrient-dense than ungerminated seeds or mature vegetables. This review also describes the environmental and priming factors that may impact the nutritional value and content of phytochemicals of microscale vegetables. These factors include the growth environment, growing substrates, imposed environmental stresses, seed priming and biostimulants, biofortification, and the effect of light in controlled environments. This review also touches on microgreen market trends. Due to their short growth cycle, nutrient-dense sprouts and microgreens can be produced with minimal input; without pesticides, they can even be home-grown and harvested as needed, hence having low environmental impacts and a broad acceptance among health-conscious consumers.

Inuloxin A Inhibits Seedling Growth and Affects Redox System of Lycopersicon esculentum Mill. and Lepidium sativum L

Allelochemicals are considered an environment-friendly and promising alternative for weed management, although much effort is still needed for understanding their mode of action and then promoting their use in plant allelopathy management practices. Here, we report that Inuloxin A (InA), an allelochemical isolated from Dittrichia viscosa, inhibited root elongation and growth of seedlings of Lycopersicon esculentum and Lepidium sativum at the highest concentrations tested. InA-induced antioxidant responses in the seedlings were investigated by analysing the contents of glutathione (GSH) and ascorbate (ASC), and their oxidized forms, dehydroascorbate (DHA), and glutathione disulphide (GSSG), as well as the redox state of thiol-containing proteins. An increase in ASC, DHA, and GSH levels at high concentrations of InA, after 3 and 6 days, were observed. Moreover, the ASC/DHA + ASC and GSH/GSSG + GSH ratios showed a shift towards the oxidized form. Our study provides the first insight into how the cell redox system responds and adapts to InA phytotoxicity, providing a framework for further molecular studies.

UV and Visible Spectrum LED Lighting as Abiotic Elicitors of Bioactive Compounds in Sprouts, Microgreens and Baby Leaves. A Comprehensive Review Including Their Mode of Action

According to social demands, the agri-food industry must elaborate convenient safe and healthy foods rich in phytochemicals while minimising processing inputs like energy consumption. Young plants in their first stages of development represent great potential. Objective: This review summarises the latest scientific findings concerning the use of UV and visible spectrum LED lighting as green, sustainable, and low-cost technologies to improve the quality of sprouts, microgreens, and baby leaves to enhance their health-promoting compounds, focusing on their mode of action while reducing costs and energy. Results: These technologies applied during growing and/or after harvesting were able to improve physiological and morphological development of sprouted seeds while increasing their bioactive compound content without compromising safety and other quality attributes. The novelty is to summarise the main findings published in a comprehensive review, including the mode of action, and remarking on the possibility of its postharvest application where the literature is still scarce. Conclusions: Illumination with UV and/or different regions of the visible spectrum during growing and shelf life are good abiotic elicitors of the production of phytochemicals in young plants, mainly through the activation of specific photoreceptors and ROS production. However, we still need to understand the mechanistic responses and their dependence on the illumination conditions.

Continuous LED Lighting Enhances Yield and Nutritional Value of Four Genotypes of Brassicaceae Microgreens

The effect of continuous lighting (CL, 24 h) and light spectrum on growth and nutritional quality of arugula (Eruca sativa), broccoli (Brassica oleracea var. italic), mizuna (Brassica rapa. var. nipposinica), and radish (Raphanus sativus var. radicula) were investigated in growth chambers under light-emitting diode (LED) and fluorescent lighting. Microgreens were grown under four combinations of two photoperiods (16 h and 24 h) providing daily light integral (DLI) of 15.6 and 23.3 mol m^-2 day^-1, correspondingly) with two light spectra: LED lamps and fluorescent lamps (FLU). The results show that fresh and dry weights as well as leaf mass per area and robust index of harvested arugula, broccoli, mizuna, and radish seedlings were significantly higher under CL compared to 16 h photoperiod regardless of light quality. There were no visible signs of leaf photodamage. In all CL-treated plants higher chlorophyll a/b and carotenoid-to-chlorophyll ratios were observed in all plants except mizuna. CL treatment was beneficial for anthocyanin, flavonoid, and proline accumulation. Higher activities of antioxidant enzymes (catalase, superoxide dismutase, ascorbate peroxidase, and guaiacol peroxidase) were also observed in CL-treated plants. In most cases, the effects were more pronounced under LED lighting. These results indicate that plants under mild oxidative stress induced by CL accumulated more non-enzymatic antioxidants and increased the activities of antioxidant enzymes. This added nutritional value to microgreens that are used as functional foods providing health benefits. We suggest that for arugula, broccoli, mizuna, and radish, an LED CL production strategy is possible and can have economic and nutritional benefits.

Effect of end-of production continuous lighting on yield and nutritional value of Brassicaceae microgreens

The effect of continuous lighting applied in the end-of-production period on growth and nutritional quality of radish (Raphanus sativus var. radicula), broccoli (Brassica oleracea var. italic), mizuna (Brassica rapa. var. nipposinica) and arugula (Eruca sativa) was investigated in growth chambers under LED lighting. Microgreens were grown under 16 h photoperiod and 3 days before harvest half of plants were placed under continuous lighting conditions. Pre-harvest continuous lighting treatment increased yield, robustness index, and shorten time to harvest in radish, broccoli, mizuna and arugula microgreens. The end-of-production treatment has also led to higher content of compounds with antioxidative properties (flavonoids, proline) and increased the activity of antioxidant enzymes (CAT, APX, GPX) by inducing mild photooxidative stress. Increased antioxidative status added nutritional value to microgreens that can be used as functional foods providing health benefits. Pre-harvest treatment by continuous lighting is suggested as the practice than can allow producers to increase yield, aesthetic appeal, nutritional quality, and market value of Brassicacea microgreens.

Elicitation: a new perspective into plant chemo-diversity and functional property

Sprouts are consumed as fresh foods or their flours can be added in processed products as determinants of sensory perception, product differentiation, and shelf life. Elicitation technique can be used to accumulate phytochemicals in plant sprouts thereby improving their functionality. This review summarized the recent state of knowledge on the use of elicitors to produce sprouts with improved functional properties. Elicitation using abiotic or biotic elicitors has been applied to increase the yield of sprout secondary metabolites (glucosinolates, aminobutyric acid, phenolic compounds), biological activities (antioxidant, anti-obesity, antidiabetic properties), and growth. Elicitors trigger the synthesis of plant metabolites by changing enzyme activities or gene expression related to the plant defence system. They also promote sprout growth by enhancing the levels of plant growth hormones. Elicitation is an effective method to produce sprouts with improved health benefits, and enhance their growth. Future studies are needed to identify early plant signaling pathways to fully understand elicitors' mechanisms on plant metabolites. Moreover, further investigation can be impetus in revealing the lower and upper limits of elicitor that can be applied in sprouts without compromising health and environmental safety.

Nutritional Improvement of Bean Sprouts by Using Chitooligosaccharide as an Elicitor in Germination of Soybean (Glycine max L.)

Soybean sprouts are among the healthiest foods consumed in most Asian countries. Their nutritional content, especially bioactive compounds, may change according to the conditions of germination. The purpose of this study was to test the effect of chitooligosaccharide with different molecular weight and dosage on nutritional quality and enzymatic and antioxidant activities of soybean sprouts. The chitooligosaccharide elicitor strongly stimulated the accumulation of vitamin C, total phenolics, and total flavonoid. The stimulation effect was correlated with the molecular weight and concentration of chitooligosaccharide. With treatment of 0.01% of 1 kDa chitooligosaccharide, the nine phenolic constituents and six isoflavone compounds were significantly increased. The antioxidant capacity (DPPH radical and hydroxyl radical scavenging activity) and antioxidase activities (catalase and peroxidase) of soybean sprouts were also enhanced after treatment with chitooligosaccharide. The degree of chitooligosaccharide-induced elicitor activity increased as the molecular weight of chitooligosaccharide decreased. These results suggest that soaking soybean seeds in a solution of chitooligosaccharide, especially in 0.01% of 1 kDa chitooligosaccharide, may effectively improve the nutritional value and physiological function of soybean sprouts.

The Arbuscular Mycorrhizal Fungus Glomus viscosum Improves the Tolerance to Verticillium Wilt in Artichoke by Modulating the Antioxidant Defense Systems

Verticillium wilt, caused by the fungal pathogen Verticillium dahliae, is the most severe disease that threatens artichoke (Cynara scolymus L.) plants. Arbuscular mycorrhizal fungi (AMF) may represent a useful biological control strategy against this pathogen attack, replacing chemical compounds that, up to now, have been not very effective. In this study, we evaluated the effect of the AMF Glomus viscosum Nicolson in enhancing the plant tolerance towards the pathogen V. dahliae. The role of the ascorbate-glutathione (ASC-GSH) cycle and other antioxidant systems involved in the complex network of the pathogen-fungi-plant interaction have been investigated. The results obtained showed that the AMF G. viscosum is able to enhance the defense antioxidant systems in artichoke plants affected by V. dahliae, alleviating the oxidative stress symptoms. AMF-inoculated plants exhibited significant increases in ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), and superoxide dismutase (SOD) activities, a higher content of ascorbate (ASC) and glutathione (GSH), and a decrease in the levels of lipid peroxidation and hydrogen peroxide (H₂O₂). Hence, G. viscosum may represent an effective strategy for mitigating V. dahliae pathogenicity in artichokes, enhancing the plant defense systems, and improving the nutritional values and benefit to human health.

Genetic and Pre- and Postharvest Factors Influencing the Content of Antioxidants in Cucurbit Crops

Cucurbitaceae is one of the most economically important plant families, and includes some worldwide cultivated species like cucumber, melons, and squashes, and some regionally cultivated and feral species that contribute to the human diet. For centuries, cucurbits have been appreciated because of their nutritional value and, in traditional medicine, because of their ability to alleviate certain ailments. Several studies have demonstrated the remarkable contents of valuable compounds in cucurbits, including antioxidants such as polyphenols, flavonoids, and carotenoids, but also tannins and terpenoids, which are abundant. This antioxidant power is beneficial for human health, but also in facing plant diseases and abiotic stresses. This review brings together data on the antioxidant properties of cucurbit species, addressing the genetic and pre- and postharvest factors that regulate the antioxidant content in different plant organs. Environmental conditions, management, storage, and pre- and postharvest treatments influencing the biosynthesis and activity of antioxidants, together with the biodiversity of this family, are determinant in improving the antioxidant potential of this group of species. Plant breeding, as well as the development of innovative biotechnological approaches, is also leading to new possibilities for exploiting cucurbits as functional products.

The Interplay between Light Quality and Biostimulant Application Affects the Antioxidant Capacity and Photosynthetic Traits of Soybean (Glycine max L. Merrill)

This paper evaluates the combined effect of biostimulant and light quality on bioactive compound production and seedling growth of soybean (Glycine max L. Merrill) plants. Germinated seeds pre-treated with different concentrations (0.01%, 0.05%, 0.5%) of an amino acid-based biostimulant were grown for 4 days at the dark (D), white fluorescent light (FL), full-spectrum LED (FS), and red-blue (RB) light. Potential changes in the antioxidant content of sprouts were evaluated. Part of the sprouts was left to grow at FL, FS, and RB light regimes for 24 days to assess modifications in plants' anatomical and physiological traits during the early developmental plant stage. The seed pre-treatment with all biostimulant concentrations significantly increased sprout antioxidant compounds, sugar, and protein content compared to the control (seeds treated with H₂O). The positive effect on bioactive compounds was improved under FS and RB compared to D and FL light regimes. At the seedling stage, 0.05% was the only concentration of biostimulant effective in increasing the specific leaf area (SLA) and photosynthetic efficiency. Compared to FL, the growth under FS and RB light regimes significantly enhanced the beneficial effect of 0.05% on SLA and photosynthesis. This concentration led to leaf thickness increase and shoot/root ratio reduction. Our findings demonstrated that seed pre-treatment with proper biostimulant concentration in combination with specific light regimes during plant development may represent a useful means to modify the bioactive compound amount and leaf structural and photosynthetic traits.

Near-Infrared Spectroscopy and Aquaphotomics for Monitoring Mung Bean (Vigna radiata) Sprout Growth and Validation of Ascorbic Acid Content

Mung bean is a leguminous crop with specific trait in its diet, namely in the form of anti-nutrient components. The sprouting process is commonly done for better nutritional acceptance of mung bean as it presents better nutritional benefits. Sprouted mung bean serves as a cheap source of protein and ascorbic acid, which are dependent on the sprouting process, hence the importance of following the biological process. In larger production scale, there has not been a definite standard for mung bean sprouting, raising the need for quick and effective mung bean sprout quality checks. In this regard, near-infrared spectroscopy (NIRS) has been recognized as a highly sensitive technique for quality control that seems suitable for this study. The aim of this paper was to describe quality parameters (water content, pH, conductivity, and ascorbic acid by titration) during sprouting using conventional analytical methods and advanced NIRS techniques as correlative methods for modelling sprouted mung beans’ quality and ascorbic acid content. Mung beans were sprouted in 6 h intervals up to 120 h and analyzed using conventional methods and a NIR instrument. The results of the standard analytical methods were analyzed with univariate statistics (analysis of variance (ANOVA)), and the NIRS spectral data was assessed with the chemometrics approach (principal component analysis (PCA), discriminant analysis (DA), and partial least squares regression (PLSR)). Water content showed a monotonous increase during the 120 h of sprouting. The change in pH and conductivity did not describe a clear pattern during the sprouting, confirming the complexity of the biological process. Spectral data-based discriminant analysis was able to distinctly classify the bean sprouts with 100% prediction accuracy. A NIRS-based model for ascorbic acid determination was made using standard ascorbic acid to quantify the components in the bean extract. A rapid detection technique within sub-percent level was developed for mung bean ascorbic acid content with R² above 0.90. The NIR-based prediction offers reliable estimation of mung bean sprout quality

Characterization of BoaCRTISO Reveals Its Role in Carotenoid Biosynthesis in Chinese Kale

Carotenoids are organic pigments that play an important role in both plant coloration and human health; they are a critical subject in molecular breeding due to growing demand for natural molecules in both food and medicine. In this study, we focus upon characterizing BoaCRTISO, the carotenoid isomerase gene before the branch of the carotenoid biosynthetic pathway, which is expressed in all organs and developmental stages of Chinese kale, and BoaCRTISO, which is located in the chloroplast. The expression of BoaCRTISO is induced by strong light, red and blue combined light, and gibberellic acid treatment, but it is suppressed by darkness and abscisic acid treatment. We obtained BoaCRTISO-silenced plants via virus-induced gene silencing technology, and the silence efficiencies ranged from 52 to 77%. The expressions of most carotenoid and chlorophyll biosynthetic genes in BoaCRTISO-silenced plants were downregulated, and the contents of carotenoids and chlorophyll were reduced. Meanwhile, BoaCRTISO-silenced plants exhibited phenotypes of yellowing leaves and inhibited growth. This functional characterization of BoaCRTISO provides insight for the biosynthesis and regulation of carotenoid in Chinese kale.

Challenges and Opportunities of Light-Emitting Diode (LED) as Key to Modulate Antioxidant Compounds in Plants. A Review

Plant antioxidants are important compounds involved in plant defense, signaling, growth, and development. The quantity and quality of such compounds is genetically driven; nonetheless, light is one of the factors that strongly influence their synthesis and accumulation in plant tissues. Indeed, light quality affects the fitness of the plant, modulating its antioxidative profile, a key element to counteract the biotic and abiotic stresses. With this regard, light-emitting diodes (LEDs) are emerging as a powerful technology which allows the selection of specific wavelengths and intensities, and therefore the targeted accumulation of plant antioxidant compounds. Despite the unique advantages of such technology, LED application in the horticultural field is still at its early days and several aspects still need to be investigated. This review focused on the most recent outcomes of LED application to modulate the antioxidant compounds of plants, with particular regard to vitamin C, phenols, chlorophyll, carotenoids, and glucosinolates. Additionally, future challenges and opportunities in the use of LED technology in the growth and postharvest storage of fruits and vegetables were also addressed to give a comprehensive overview of the future applications and trends of research.

The Effect of Light on Antioxidant Properties and Metabolic Profile of Chia Microgreens

Chia (Salvia hispanica L.) is a one-year plant known as a source of nutrients that can be consumed in the diet in the form of seeds or sprouts. The purpose of this study is to investigate the effect of illumination for 24 and 48 h on dark-grown chia microgreens. Total antioxidant capacity was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP) assays, along with the total phenolics, ascorbic acid and cellulose content, and chlorophyll and carotenoid concentrations. Fourier transform infrared spectroscopy (FTIR) was used to evaluate the biochemical composition and elucidate the changes in compound structures between dark-grown and illuminated chia microgreens. Analysis of the results showed that illumination significantly increased the content of all measured bioactive compounds as well as antioxidative capacity, especially 48 h after exposure to light. FTIR analyses supported structural and molecular changes in chia microgreens grown under different light regimes. Our results suggest that illumination has a positive effect on the antioxidant potential of chia microgreens, which may present a valuable addition to the human diet.