Light quality is a powerful tool to modulate the chemistry of functional foods, yet the underlying molecular regulatory networks are poorly understood. This study reveals that purple light-emitting diode illumination engineers the metabolic flux in flowering Chinese cabbage sprouts to maximize the production of the anti-cancer agent sulforaphane. Compared to dark and white light controls, purple light treatment (center wavelength: 398 nm, half-width: 13 nm) resulted in a significant (6.84-fold) increase in sulforaphane content. Integrated metabolomic and transcriptomic analyses uncovered a "push-pull" mechanism: purple light "pushed" glucosinolate biosynthesis while "pulling" the metabolic stream towards sulforaphane by enhancing hydrolysis and suppressing the competing nitrile-forming pathway. We identified the transcription factor BcHY5 as the master regulator. Yeast one-hybrid and dual-luciferase assays confirmed BcHY5 directly binds to and activates promoters of key GSL biosynthetic genes (GSTU11, SUR1). These findings establish a novel light-regulatory framework, offering a practical strategy for the precision production of high-value phytochemicals in functional foods.

Cadmium (Cd), a highly toxic heavy metal, poses significant threats to agricultural productivity and human health by accumulating in the food chain. Selenium (Se), an essential micronutrient, has shown promise in mitigating Cd toxicity in plants. However, the underlying molecular mechanisms remain largely unknown. This study elucidates how exogenous selenite (Na2SeO3) reduces Cd accumulation in the edible parts of flowering Chinese cabbage. Our results demonstrate that Se application (2.5 µM) dramatically mitigated Cd-induced growth inhibition, recovering shoot and root biomass to 96.3% and 90.7% of those of the control levels, respectively, while significantly decreasing Cd concentration in the shoots. Mechanistically, Se orchestrates a multi-layered defense strategy in the roots under Cd stress. Ultrastructural and physiological analyses revealed that, Se reduced the average net Cd2 + influx by 24.3%, increased root cell wall thickness by 40%, and significantly boosted cell wall lignification under Cd stress. Furthermore, Se promoted Cd compartmentalization by shifting Cd from metabolically sensitive organelles to the soluble fraction under Cd stress. At the molecular level, transcriptome analysis combined with Weighted Gene Co-expression Network Analysis (WGCNA) identified a potential regulatory module. The transcription factor bHLH39 acts as a key repressor, directly binding to the promoter of the lignin biosynthesis gene CAD5. Se co-application suppresses the Cd-induced expression of bHLH39, thereby de-repressing CAD5 expression to promote lignification and physically restrict Cd translocation. This study identified the bHLH39-CAD5 regulatory module as a potential mechanism underlying Se-mediated Cd detoxification, providing a strategy for improving low-Cd leafy vegetables crops to ensure food safety.

Sulforaphane (SFN), a high-value nutraceutical derived from glucosinolates (GSLs) in broccoli sprouts, can be enhanced by the plant hormone abscisic acid (ABA). However, the underlying molecular mechanism is poorly understood, limiting its practical application. Here, we used an integrated approach combining metabolomics, time-series transcriptomics, and molecular validation to elucidate how exogenous ABA regulates GSLs metabolism in broccoli sprouts. Treatment with 50 μmol/L ABA resulted in a 1.89-fold increase in SFN content. Metabolomics revealed that ABA selectively remodeled the GSLs profile, preferentially promoting short-chain aliphatic GSLs while inhibiting indolic GSLs. Transcriptomics uncovered a dual-action mechanism: ABA upregulated key GSL biosynthesis genes (BCAT2, SUR1, SOT17) and simultaneously downregulated the epithiospecifier protein (ESP) gene, which diverts hydrolysis away from SFN. This coordinated regulation ensures efficient SFN accumulation. Weighted Gene Co-expression Network Analysis (WGCNA) identified BoCOL15 as a key ABA-responsive transcription factor. Yeast one-hybrid and dual-luciferase assays confirmed that BoCOL15 directly binds to and activates the promoters of two core biosynthesis genes, BoGGP1 and BoSOT17. In conclusion, ABA enhances SFN through a BoCOL15-mediated dual mechanism that both boosts precursor synthesis and guides metabolic flux. BoCOL15 is a novel molecular hub connecting ABA signaling to GSLs metabolism and represents a prime target for the molecular breeding and biofortification of broccoli.

Soil salinity affects the distribution of fruit trees and limits the development of the fruit industry. Rootstock plays an important role in improving the stress resistance of fruit trees.This study investigates the effects of four pear rootstock clones —QNA201 (Pyrus calleryana Decne.), QAUP-1 (P. ussuriensis Maxim), QingzhenD1 (P. communis L.× P. bretschneideri Rehd) and OHF40 (P. communis L) on the salt tolerance of the grafted variety ‘Luxiu’(P.pyrifolia Nakai cv.’Luxiu’) and explores the underlying mechanisms. Rootstocks and grafted seedlings were subjected to different concentrations of NaCl treatments (0 mM, 100 mM, and 200 mM for rootstocks; 200 mM for grafted seedlings). A number of physiological and biochemical indexes were determined, including salt injury index, chlorophyll content, photosynthetic parameters (PN, ET, gS), activities of antioxidant enzymes (SOD, POD, CAT), as well as contents and distribution of Na⁺ and K⁺.The results showed that QNA201 and Qingzhen D1 exhibited strong salt tolerance, with lower salt injury indexes, more stable photosynthetic performance, and more favorable distribution of Na⁺ and K⁺. The aboveground parts of rootstocks QNA201 and Qingzhen D1 accumulated less Na⁺ and could maintain a higher K⁺ level. The salt tolerance of grafted seedlings was consistent with that of the rootstocks. L/QNA201 and L/Qingzhen D1 had less salt damage, higher SPAD values, and stronger antioxidant activity. Na⁺ was concentrated in the roots and grafting bases, while K⁺ was enriched in the aboveground parts (especially in the leaves of L/Qingzhen D1). Transcriptomic analysis revealed significant differences in gene expression related to hormone regulation, ion transport, and antioxidant pathways in salt-tolerant rootstocks. QingzhenD1 displayed higher expression of genes involved in salicylic acid synthesis, auxin and ethylene-responsive transcription factors, and the antioxidant system, indicating its role in enhancing salt tolerance. These findings highlight the potential of QNA201 and QingzhenD1 as effective rootstocks to improve the salt tolerance of pear cultivars.

Sulforaphane (SFN) is widely recognized for its health-promoting benefits. While several studies have reported that methyl jasmonate (MeJA) enhances SFN accumulation, the role of epigenetic regulation remains unclear. Here, we performed an integrated analysis of transcriptome, whole-genome bisulfite sequencing, and small RNA-seq data from broccoli florets and leaves under MeJA treatment and control conditions. Our results revealed that MeJA-responsive differentially methylated regions (DMRs) predominantly occurring in the CHG context. Integrative analysis of methylation and siRNA data indicated that changes in MeJA-responsive CHH methylation were associated with 24-nucleotide siRNA clusters. Furthermore, inhibiting DNA methylation using 5-azacytidine treatment in broccoli seedlings increased SFN content, validating the role of DNA hypomethylation in this process. By combining transcriptional regulatory network analysis with DMR data, we identified the MeJA-responsive CHG-hypomethylated gene BoCYP83A1. The McrBC-PCR assay confirmed reduced methylation in the BoCYP83A1 promoter region. The function of BoCYP83A1 in MeJA-induced SFN biosynthesis was validated using RNA interference in broccoli. Further evidence demonstrated that the transcription factors BoMYB68 and BoIAA18 promote BoCYP83A1 expression by directly binding to its promoter. Our findings not only provide novel insights into the epigenetic regulation underlying MeJA-induced SFN accumulation in plants but also facilitate molecular breeding for the development of high-SFN crops.

To address the current mismatch between processing pepper cultivars and the requirements of mechanized production, this study aims to construct a comprehensive evaluation model for the suitability of mechanized transplanting and harvesting, thereby screening highly adaptable varieties. An evaluation system comprising eight indicators for the transplanting stage and thirteen indicators for the harvesting stage was established using 105 processing pepper varieties (including 56 erect-fruit and 49 pendent-fruit peppers). Variation analysis, hierarchical clustering, principal component analysis (PCA), and Pearson correlation analysis were integrated to reveal the clustering effects of the cultivars and the synergistic and antagonistic relationships among the indicators. Furthermore, a combined CRITIC-VIKOR model was applied to conduct a multi-criteria comprehensive ranking of mechanization suitability. The results indicated that the biomechanical properties of processing peppers exhibited a significantly higher degree of variation than conventional morphological indicators (e.g., the coefficient of variation for lodging resistance reached 93.60%). Significant differences were observed in the mechanization adaptation mechanisms between the two pepper types: erect-fruit peppers were primarily limited by fruiting branch toughness (weight: 5.907%), whereas pendent-fruit peppers were mainly constrained by fruit morphological uniformity. Compared with the traditional PCA model, the CRITIC-VIKOR model effectively identified varieties with critical biomechanical defects by constraining the "individual regret value", which highly aligns with Liebig's Law of the Minimum in mechanized operations. Based on this model, varieties with superior comprehensive mechanization adaptability were successfully identified, notably C21, C55, and C23 (erect-fruit peppers), and D20, D11, and D19 (pendent-fruit peppers). This study provides a theoretical foundation and mathematical modeling support for the directional breeding of mechanization-suitable cultivars, the integration of agronomy and agricultural machinery, and the quantitative evaluation of multi-trait pyramiding in processing peppers.

Selenium (Se) enriched forest-grown ginseng is famous for its high Se content and excellent protein quality, which are necessary for varieties of metabolic processes and play an important role in both ginseng growth and its health benefits for humans. However, the regulatory mechanism underlying Se enrichment and molecular responses of forest-grown ginseng after application of exogenous Se is still unclear. This study investigated the effect of Se fertilizer on molecular changes in physiological metabolisms of forest-grown ginseng during the growth process by analyzing differentially expressed proteins (DEPs). The results showed that 371 proteins were significantly changed under application of Se fertilizer. Further KEGG pathway analysis indicated that the DEPs are primarily involved in carbon metabolism, biosynthesis of amino acids, protein processing in endoplasmic reticulum, phenylpropanoid biosynthesis, oxidative phosphorylation and spliceosome. The expression levels of ATP sulfurylase, adenosine 5’-phosphosulfate reductase, nitrate reductase, nitrite reductase, superoxide dismutase, catalase, and H⁺-ATPase were up-regulated in ginseng treated with Se, and these key DEPs were mainly related to the maintenance of cellular membrane, antioxidant capacity and resistance to stresses. These findings reveal the nutritional and functional differences and establish a theoretical basis for further research on protein biological functions in forest-grown ginseng.

Broccoli sprouts, valued for their high nutritional content and richness in sulforaphane (SF), exhibit quality traits that are significantly modulated by light quality. However, the mechanisms underlying light regulation of glucosinolate (GSLs) biosynthesis in sprouts remain elusive. This study employed broccoli ‘Xianglv No. 3’ sprouts as experimental material, comparing sprouts grown in darkness (control) with those under five distinct LED light spectra. We assessed sprout growth, quantified GSLs and SF levels, measured total antioxidant capacity, and evaluated cytotoxicity against cancer cells. Integrated metabolomic and transcriptomic analyses were subsequently conducted. Results demonstrated that blue light significantly enhanced GSLs biosynthesis and SF accumulation in broccoli sprouts compared to the dark control, concurrently boosting antioxidant capacity and reducing cancer cell proliferation. Metabolomic profiling revealed significant alterations in 19 GSL metabolites under blue light, with 6 up-regulated and 13 down-regulated. Aliphatic GSLs exhibited the most pronounced changes, while SF increased markedly. Transcriptome analysis identified 9,128 differentially expressed genes (DEGs) in response to blue light. The results suggested that blue light regulated GSLs biosynthesis, particularly AGS, potentially by inhibiting carbon chain elongation and secondary modifications in their side chains. We propose a regulatory model of the HY5-MYB28-CYP83A1 signaling cascade. In this model, blue light induces the up-regulation of the light-responsive transcription factor HY5. HY5 subsequently activates the expression of its downstream target, MYB28, which in turn upregulates CYP83A1, ultimately driving enhanced GSL and SF production. This study elucidates the molecular basis for light quality regulation of broccoli sprout quality and provides valuable insights for advancing efficient cultivation and quality enhancement strategies.

The ZF-HD transcription factors play key roles in plant development and stress responses, yet their functions in cucumber remain poorly understood. Here, we characterized a cucumber ZF-HD gene, CsHB33, and investigated its role in leaf development and drought tolerance. CsHB33 was highly expressed in developing leaves. Its expression was significantly suppressed by abscisic acid (ABA) and down-regulated under drought stress. Heterologous overexpression of CsHB33 in Arabidopsis promoted leaf growth by increasing cell size, but simultaneously enhanced sensitivity to osmotic and drought stress, accompanied by higher stomatal aperture and water loss. Transcriptomic analysis revealed that CsHB33 overexpression up-regulated genes associated with leaf enlargement, while under drought it led to constitutive activation of aromatic amino acid biosynthesis, particularly tryptophan metabolism. This metabolic disturbance likely contributes to the drought-sensitive phenotype. Our findings reveal that CsHB33 exerts opposing effects on leaf growth and drought tolerance, providing new insights into ZF-HD gene function in cucumber and identifying a potential target for improving stress resilience in breeding.

Background: The TGACG-BINDING FACTORS (TGA) gene family, a key subgroup of bZIP transcription factors, mediates plant stress responses and developmental processes by binding to the as-1 cis-element in target gene promoters to regulate transcriptional activation or repression. Despite its functional significance, systematic characterization of TGA genes in cotton (Gossypium spp.) remains insufficient. Methods: In this study, we performed a comprehensive genome-wide identification and phylogenetic analysis of TGA members across 10 Gossypium species and verified the functions of candidate genes using VIGS technology. Results: A total of 74 TGA homologous genes with conserved DOG1 and bZIP domains were identified. Evolutionary analysis revealed that the cotton TGA gene family can be classified into five distinct branches, suggesting functional diversification. Functional prediction analyses indicated these genes in cotton growth regulation and stress adaptation, potentially through hormone-mediated signaling pathways. Expression profiling demonstrated both tissue-specific expression patterns and salt-stress responsiveness in Gossypium hirsutum TGA genes, and GhTGA2 exhibited the most significant up-regulated expression under salt stress. Virus-induced gene silencing (VIGS)-mediated GhTGA2 silencing significantly reduced the salt tolerance in cotton. Conclusions: The TGA gene family is involved in regulating cotton growth, development, and stress responses, and plays a critical role in mediating salt stress tolerance in cotton. Our results provide mechanistic insights into cotton stress adaptation and establish a valuable genetic resource for developing elite salt-tolerant cotton cultivars, with direct implications for sustainable cotton production.

Purple flowering stalk, with vivid color and high yield, is a special vegetable rich in glucosinolates. This study analyzed and evaluated the variability of agronomic traits and nutritional quality of 127 genotypes of purple flowering stalks. The results showed that the genetic diversity index of qualitative traits varied from 0.16 (leaf vein clarity) to 1.57 (cotyledon color), and quantitative traits varied from 1.48 (rosette number) to 2.06 (cotyledon groove depth). Moreover, the highest coefficient of variation in quantitative traits was found in three yield-related traits: main flowering stalk weight, main flowering stalk length, and lateral flowering stalk number (63.35 %, 45.17 %, and 46.57 %, respectively). Cluster analysis divided accessions into three major clusters. The hierarchical cluster analysis implied that the yield-related traits and nutritional traits contribute most to the distinction. In principal component analysis based on yield and nutritional traits, the eight components explained 76.4 % of the variance in the data. All varieties were evaluated by comprehensive score, and the top ten of them (CS 70, CS 56, CS 105, CS 114, CS 113, CS 129, CS 93, CS134, CS 35, CS 74) with different characters can be used in the improvement of breeding. Correlation analysis suggested that shorter flowering stalks may have more content of total glucosinolates, ascorbic acid, and soluble protein. In conclusion, this work provides basic materials and theories for purple flowering stalk breeding.

Background and Aims Chinese cabbage (Brassica rapa ssp. pekinensis) is a crucial leafy vegetable crop in China and globally. It ranks first in terms of planting area and output among all vegetables and is an important economic and livelihood-supporting crop. Methods This study investigated the effects of five concentrations (15, 24, 36, 60, and 72 L/hectare) of a Si-containing water-soluble fertilizer applied via root irrigation on cabbage cultivar 'Jingcui 60' under greenhouse conditions. Reselts Results showed that moderate Si application (T3 and T4) significantly promoted plant growth, with T3 increasing shoot fresh weight by 47.8%. Si fertilization also enhanced cabbage quality, with T4 increasing leaf amino acid content by 99% and T2 boosting soluble sugar content by 42.25%. Soil analysis revealed that Si increased soil EC, organic matter, and alkali-hydrolyzable nitrogen and enhancing soil enzyme activities. Microbial profiling showed that Si reshaped bacterial and fungal communities, in creasing bacterial richness, promoting beneficial genera like Bacillus, and suppressing pathogenic fungi such as Fusarium. Conclutions The 60 L/hectare application rate (T4) provided the most benefits. This study clarifies the soil-microbe-plant interactions in Si-mediated quality regulation and provides a basis for precise Si fertilizer application in sustainable leafy vegetable production.

Sulforaphane (SF) is a sulfur (S)-containing isothiocyanate found in cruciferous vegetables and is known for its potent anticancer properties. Broccoli sprouts, in particular, are considered safe and healthy dietary choices due to their high SF content and other beneficial biological activities, such as enhanced metabolite ingestion. The application of selenium (Se) is an excellent approach to enhance the abundance of SF. Previous studies have often focused on gene expression and changes in the synthetic substrates of glucoraphanin (RAA) to explain SF variation in response to Se application. However, the regulatory network and other physiological and biochemical reactions involved in the regulation of SF biosynthesis are poorly understood. In this study, Se-treated broccoli sprouts had higher SF and RAA contents; they increased with increasing Se application. Using RNA-seq in combination with KEGG, GO, phenotypic, and WGCNA analyses, it was observed that not only gene expression was induced but also that glutathione serves as an S donor for SF biosynthesis and acts as an oxidative stress reliever as a result of Se treatment. Additionally, a module related to glucosinolate biosynthesis was identified. Yeast one-hybrid system and dual luciferase reporter assay were utilized. These assays demonstrated the hub transcription factors GATA22, ERF12-like, and MYB108 would directly bind to SUR1 promoter and positively regulate its expression. Our study presents the first global overview of the role of GSH metabolism in response to Se for SF biosynthesis, and provides a novel and valuable gene resource for the molecular breeding of high-SF broccoli.

The SNAC (Stress-responsive NAC) subfamily, a key branch of the conserved NAC transcription factor family, plays a central role in regulating plant stress response. However, systematic characterization of the SNAC family in cotton (Gossypium spp.) remains unclear. Employing a genome-wide screening approach, this study characterized 75 distinct SNAC transcription factor genes across ten Gossypium species, with tetraploid cottons harboring twice as many as their diploid progenitors. Phylogenetic analysis categorized the genes into three subgroups, with members of the same subgroup exhibiting conserved motif compositions and gene structures. Chromosomal localization revealed a conserved distribution pattern of SNAC genes between the Dt and At subgenomes in tetraploid cotton. Genomic collinearity analysis suggested that the primary driver of SNAC family expansion was segmental duplication. Promoter analysis predicted 2974 cis-regulatory elements, including cold- and hormone-responsive motifs, indicating their potential involvement in stress regulation. These GhSNAC genes indicated significant induced expressions under stress conditions, and GhSNAC3D exhibited the most significant up-regulated expression under low temperature stress. Genetic function studies displayed that VIGS-mediated GhSNAC3D-silencing significantly reduced the cold tolerance in cotton. This study systematically analyzed the genomic characteristics of the cotton SNAC family and functionally validated the molecular mechanism of GhSNAC3D-mediated cryogenic response, which lays a foundation for subsequent research on cold resistance in cotton and stress-resistant breeding.

Broccoli is an economically significant vegetable with high nutritional and medicinal value. Seed size/weight is one of the important agronomic traits that determine crop yield, which is regulated by multiple plant hormones. However, limited information is known about the regulation of seed size control in broccoli. Here, we report that the basic helix-loop-helix transcription factor BoMYC2 exerts a negative regulatory influence on seed-related traits in broccoli. The overexpression of BoMYC2 in Arabidopsis and broccoli led to notably decreased seed size and seed weight, likely by repressing cell proliferation of embryonic. Besides, overexpression of BoMYC2 increased the fatty acid accumulation while reducing the protein and soluble sugar levels in stably transgenic broccoli seeds, affecting seed storage compounds composition and seed size. Based on DNA affinity purification sequencing, BoMYC2 targeted the cytokinin oxidase gene BoCKX5 by binding to the G-box motif in its promoter regions. BoMYC2 activated the expression of BoCKX5 to modulate cytokinin metabolism. The expression levels of cytokinin-related genes and jasmonic acid-related genes were further analyzed in transgenic broccoli seeds, implying that BoMYC2 leads to higher jasmonic acid and lower cytokinin hormone content, which might affect the cell proliferation in seeds. Furthermore, cytokinin levels were significantly lower in BoMYC2-overexpressing broccoli than in wild-type plants. Collectively, these findings reveal a BoMYC2-BoCKX5 regulatory module that controls seed size/weight, enriching our understanding of the internal mechanism in seed size regulation and providing promising targets for high-yield broccoli breeding.

Using “Ba Xuan No. 3” as the experimental material, this study established different fertilization ratios, including 112.5 kg·hm-2 of compound fertilizer (CK), 78 kg·hm-2 of compound fertilizer combined with 12 × 103 kg·hm-2 of sheep manure (T1), 18 × 103 kg·hm-2 (T2), 24 × 103 kg·hm-2 (T3), and 30 × 103 kg·hm-2 (T4). The study investigated the effects of different fertilization ratios on the dry matter and nitrogen accumulation and distribution in flax, aiming to explore fertilization measures for improving flax yield and efficiency. The results showed that the combined application of organic and inorganic fertilizers significantly increased soil organic matter, alkaline nitrogen, and available potassium, meeting the growth requirements of flax to the greatest extent. In the T4 treatment, photosynthetic parameters, chlorophyll content, and nitrogen fertilizer utilization efficiency were also higher which provided a physiological basis for stable yields after applying organic fertilizers. The T4 treatment had the highest accumulation of dry matter in the above-ground parts of flax and the highest dry matter allocation ratio of flax capsules in the mature period. Under the organic fertilizer treatment, the nitrogen nutrient accumulation in leaves during the bud stage was significantly higher than in CK, with the T4 treatment reaching the highest level. Correlation analysis revealed that the amount of nitrogen fertilizer applied was negatively correlated with nitrogen fertilizer utilization efficiency, while seed yield was positively correlated with nitrogen fertilizer utilization efficiency. The seed yield in the T4 treatment was significantly higher than conventional fertilization treatment, increasing by 8.61%. In summary, applying 78 kg·hm-2 of compound fertilizer with 30 × 103 kg·hm-2 of sheep manure significantly enhanced the accumulation of dry matter in flax and the dry matter allocation rate of flax capsules in the mature period.

Sulforaphane, a naturally specialized metabolite, plays significant roles in human disease prevention and plant defense. Myrosinase (MY) is a key gene responsible for the catalysis of sulforaphane formation, but the molecular mechanisms through which MY regulates sulforaphane biosynthesis in plants remains largely unknown. Here, we discovered that the change of sulforaphane content in broccoli sprouts caused by exogenous selenite treatments is positively related to BoMY expression. BoMY overexpression in the Arabidopsis thaliana tgg1 mutants could dramatically increase myrosinase activity and sulforaphane content in the rosette leaves of 35S::BoMY/tgg1 and rescue its phenotypes. Moreover, an obvious increase of myrosinase activity and sulforaphane content was displayed in transgenic BoMY-overexpressed broccoli lines. In addition, a 2 033 bp promoter fragment of BoMY was isolated. Yeast one-hybrid (Y1H) library screening experiment uncovered that one bHLH transcription factor, BoFAMA, could directly bind to BoMY promoter to activate its expression, which was further evidenced by Y1H assay and dual-luciferase reporter assay. BoFAMA is a selenite-responsive transcription factor that is highly expressed in broccoli leaves; its protein is solely localized to nucleus. Additionally, genetic evidence suggested that the knockdown of FAMA gene in Arabidopsis thaliana could significantly decrease sulforaphane yield by inhibiting the expression of myrosinase genes. Interestingly, exogenous selenite supply could partially restore the low level of sulforaphane content in transgenic Arabidopsis FAMA-silencing plants. Our findings uncover a novel function of FAMA-MY module in the regulation of selenite-mediated sulforaphane synthesis and provide a new insights into the molecular mechanism by which selenite regulates the accumulation of sulforaphane in plants.

Light quality optimization is a cost-effective method for increasing leafy vegetable quality in plant factories. Light-emitting diodes (LEDs) that enable the precise modulation of light quality were used in this study to examine the effects of red-blue (RB), red-blue-green (RBG), red-blue-purple (RBP), and red-blue-far-red (RBF) lights on the growth, antioxidant capacity, and nitrogen metabolism of Chinese cabbage leaves, while white light served as the control (CK). Results showed that the chlorophyll, carotenoid, vitamin C, amino acid, total flavonoid, and antioxidant levels of Chinese cabbage were all significantly increased under RBP combined light treatment. Meanwhile, RBG combined light treatment significantly increased the levels of amino acids but decreased the nitrite content of Chinese cabbage. In addition, RBF combined light treatment remarkably increased the amino acid levels but decreased the antioxidant capacity of Chinese cabbage. In conclusion, the addition of purple light to red-blue light was effective in improving the nutritional value and antioxidant capacity of Chinese cabbage. This light condition can be used as a model for a supplemental lighting strategy for leafy vegetables in plant factory production.

Selenocysteine methyltransferase (SMT) is a key enzyme involved in the Se metabolism pathway, and it is responsible for the catalysis of Se-methylselenocysteine (SeMSC) compound formation. Previous studies showed that selenium treatment activated SMT expression and promoted the accumulation of glucosinolates (GSLs) and sulforaphane, but the roles and functional mechanisms of SMT in mediating GSLs and sulforaphane synthesis remain unclear. In this study, we identified the BoSMT gene in broccoli and uncovered its roles in mediating GSLs biosynthesis. Transgenic assays revealed that BoSMT is involved in SeMSC biosynthesis in broccoli. More importantly, the contents of GSLs and sulforaphane were significantly increased in the BoSMT-overexpressing broccoli lines but decreased in the knockdown lines, suggesting that BoSMT played a positive role in regulating GSLs and sulforaphane synthesis. Further evidence indicated that BoSMT-mediated overaccumulation of GSLs and sulforaphane might be due to the increase in the endogenous SeMSC content. Compared with the mock (water) treatment, selenite-induced significantly increases of the SeMSC content in the BoSMT-knockdown plants partially compensated the phenotype of GSLs and sulforaphane loss. Compared with the mock treatment, exogenous SeMSC treatment significantly increased the contents of GSL and sulforaphane and activated GSL synthesis-related gene expression, suggesting that SeMSC acted as a positive regulator for GSL and sulforaphane production. Our findings provided novel insights into selenium-mediated GSLs and sulforaphane accumulation. The genetic manipulation of BoSMT might be a useful strategy for improving the dietary nutritional values of broccoli.