Aliphatic Glucosinolates Research Articles

Emerging roles of auxin in plant abiotic stress tolerance.

Plants are continuously attacked by several biotic and abiotic factors. Among abiotic factors, heat, cold, drought, and salinity are common stresses. Plants produce several hormones as their main weapon in fightback against these stresses. Among these hormones, the role of auxin is well established in regulating plant growth and development at various scales. However, in recent literature, the important role of auxin in abiotic stress tolerance has emerged. Several auxin signalling and transport mutants exhibit heat, drought, and salinity-related phenotypes. Among them, auxin-mediated hypocotyl elongation and root growth in response to increased heat are of importance due to the continuous rise in global temperature. Auxin is also involved in regulating and recruiting specialized metabolites like aliphatic glucosinolate to defend themselves from drought stress. Aliphatic glucosinolate (A-GLS) regulates guard cell closure using auxin, which is independent of the major abiotic stress hormone abscisic acid. This regulatory mechanism serves as an additional layer of guard cell movement to protect plants from drought. Transferring the aliphatic glucosinolate pathway into non-brassica plants such as rice and soybean holds the promise to improve drought tolerance. In addition to these, post-translational modification of auxin signalling components and redistribution of auxin efflux transporters are also playing important roles in drought and salt tolerance and, hence, may be exploited to breed drought-tolerant crops. Also, reactive oxygen species, along with peptide hormone and auxin signalling, are important in root growth under stress. In conclusion, we summarize recent discoveries that suggest auxin is involved in various abiotic stresses.

Effects of Postharvest SO2 Treatment on Longan Aril Flavor and Glucosinolate Metabolites.

SO2 fumigation treatment (commonly known as sulfur treatment, ST) is a key method in the postharvest preservation of imported and exported fresh longan fruits, effectively reducing pericarp browning and enhancing color. Nonetheless, distinctive aromas, often referred to as "sulfur flavor", may develop in the aril during the extended preservation period. This study employed "Caopu" longan as the test material and patented SO2-releasing paper (ZL201610227848.7) as a treatment to perform a 35-day low-temperature (5 °C) storage of the fruit. The changes in glucosinolates (GSLs) and associated metabolites in the aril of treated fruit (ST) were examined utilizing ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection and widely targeted metabolomics technology. The findings indicated that following 35 days of storage, nearly all control (CK) fruit pericarp turned to brown, resulting in an edible fruit rate of 75.41% and a commercial fruit rate of 0%. In contrast, the treated (ST) fruit demonstrated an edible fruit rate and a commercial rate of 99.44%, while the pericarp color changed from dark yellow-brown to light earthy yellow. The sulfur-containing metabolites identified in longan fruit aril predominantly consist of amino acids and their derivatives (60.44%), followed by alkaloids (15.38%), nucleotides and their derivatives (1.10%), and other types (23.08%), which include GSLs. SO2 treatment significantly reduced the content of oxidized glutathione in fruit aril but increased the content of GSLs and related amino acids and their derivatives. Via screening, 19 differential sulfur-containing metabolites were obtained between ST and CK, including 11 GSLs. The identified differential metabolites of GSLs were all increased, primarily comprising aliphatic GSLs, such as 1-hydroxymethyl glucosinolate, 2-Propenyl glucosinolate (Sinigrin), and 4-Methylsulfinylbutyl glucosinolate (Glucoraphanin). Pathway analysis showed that these differential metabolites were mainly involved in coenzyme factor synthesis, cysteine and methionine metabolism, and amino acid synthesis, among other pathways. To the best of our knowledge, this is the first study to reveal the causes of the special flavor of longan aril after SO2 treatment, which is a great concern for longan consumers. Moreover, this study provides a scientific basis for exploring the reasons and mechanisms for the development of the sulfur flavor in the SO2-treated fruits during postharvest storage.

Selenium Enhances Growth, Phenolic Compounds, Antioxidant Capacity in Brassica Oleracea Var. Italica.

Selenium is a micronutrient element that is beneficial for the growth and development of plants. It has antioxidant, anticancer, and antiviral properties that are essential for human and animal health. Low-consumption mineral elements such as selenium can be included in the diet from various sources. To investigate the growth and phytochemical attributes of a broccoli cultivar "Heracklion", an experiment with five levels of selenium concentration (0, 5, 10, 15, 20 mg/L sodium selenate) was carried out in a randomized complete block design with 3 replications in the field condition. With increasing the concentration of sodium selenate in the foliar application, the accumulation of sodium selenate in broccoli increased and the highest amount (1.47 mg/kg dry weight) was measured at 20 mg/L of sodium selenate. The highest amount of photosynthetic pigments in leaves was recorded at 15 mg/L of sodium selenate. In the case of glucosinolates, with increasing selenium concentration up to 20 mg/L concentration, glucoraphanin, 4-methoxy glucobrassicin, and aliphatic glucosinolates increased in leaves. It could be demonstrated that foliar application of selenium at 10 mg/L led to an improvement of secondary metabolites, especially glucoraphanin, both in leaves and florets, and could also have a positive effect on human nutrition.

Glucosinolate structural diversity shapes recruitment of a metabolic network of leaf-associated bacteria

Host defenses can have broader ecological roles, but how they shape natural microbiome recruitment is poorly understood. Aliphatic glucosinolates (GLSs) are secondary defense metabolites in Brassicaceae plant leaves. Their genetically defined structure shapes interactions with pests in Arabidopsis thaliana leaves, and here we find that it also shapes bacterial recruitment. In model genotype Col-0, GLSs (mostly 4-methylsulfinylbutyl-GLS) have no clear effect on natural leaf bacterial recruitment. In a genotype from a wild population, however, GLSs (mostly allyl-GLS) enrich specific taxa, mostly Comamonadaceae and Oxalobacteraceae. Consistently, Comamonadaceae are also enriched in wild A. thaliana, and Oxalobacteraceae are enriched from wild plants on allyl-GLS as carbon source, but not on 4-methylsulfinylbutyl-GLS. Recruitment differences between GLS structures most likely arise from bacterial myrosinase specificity. Community recruitment is then defined by metabolic cross-feeding among bacteria. The link of genetically defined metabolites to recruitment could lead to new strategies to shape plant microbiome balance.

Plant defense compounds can enhance antagonistic effects against Alternaria brassicicola of seed-associated fungi isolated from wild Brassicaceae.

Plant microbiota appear more and more as potential sources of antagonistic microorganisms. However, the seed microbiota associated with wild plant species has rarely been explored. To identify fungal antagonists to the seed-borne pathogen Alternaria brassicicola, seeds were collected in natural populations of three Brassicaceae species, Arabidopsis thaliana, Capsella bursa-pastoris and Draba verna. A large number of fungal strains reduced the growth of A. brassicicola. The most antagonistic strains belonged to Alternaria, Apiospora, Trichoderma and Aspergillus. Seed-associated fungi tolerated host plant defenses and exhibited lower sensitivity compared to A. brassicicola to indolic compounds such as the phytoalexin camalexin and the glucosinolates (GLS)-breakdown compound indole-3-carbinol. By contrast, antagonistic strains were as inhibited as A. brassicicola in presence of allyl-isothiocyanates (ITC) derived from aliphatic GLS, and more inhibited by benzyl-ITC derived from aromatic GLS. However, all defense compounds could enhance the antagonistic effects of some of the isolated strains on A. brassicicola. The observed potential synergistic effects between defense compounds and seed-associated antagonistic strains emphasize the need for further studies to elucidate the molecular bases of the interactions. A better understanding of the interactions between host plants, pathogens and fungal endophytes is also needed to develop sustainable biocontrol strategies.

Bivariate GWA mapping reveals associations between aliphatic glucosinolates and plant responses to thrips and heat stress.

Although plants harbor a huge phytochemical diversity, only a fraction of plant metabolites is functionally characterized. In this work, we aimed to identify the genetic basis of metabolite functions during harsh environmental conditions in Arabidopsis thaliana. With machine learning algorithms we predicted stress-specific metabolomes for 23 (a)biotic stress phenotypes of 300 natural Arabidopsis accessions. The prediction models identified several aliphatic glucosinolates (GLSs) and their breakdown products to be implicated in responses to heat stress in siliques and herbivory by Western flower thrips, Frankliniella occidentalis. Bivariate GWA mapping of the metabolome predictions and their respective (a)biotic stress phenotype revealed genetic associations with MAM, AOP, and GS-OH, all three involved in aliphatic GSL biosynthesis. We, therefore, investigated thrips herbivory on AOP, MAM, and GS-OH loss-of-function and/or overexpression lines. Arabidopsis accessions with a combination of MAM2 and AOP3, leading to 3-hydroxypropyl dominance, suffered less from thrips feeding damage. The requirement of MAM2 for this effect could, however, not be confirmed with an introgression line of ecotypes Cvi and Ler, most likely due to other, unknown susceptibility factors in the Ler background. However, AOP2 and GS-OH, adding alkenyl or hydroxy-butenyl groups, respectively, did not have major effects on thrips feeding. Overall, this study illustrates the complex implications of aliphatic GSL diversity in plant responses to heat stress and a cell-content-feeding herbivore.

Kinetic and catalytic mechanism of the methionine-derived glucosinolate biosynthesis enzyme methylthioalkylmalate synthase

In Brassica plants, methionine-derived aliphatic glucosinolates are chemically diverse natural products that serve as plant defense compounds, as well as molecules with dietary health-promoting effects. During their biosynthesis, methylthioalkylmalate synthase (MAMS) catalyzes the elongation reaction of the aliphatic chain. The MAMS catalyzed condensation of 4-methylthio-2-oxobutanoic acid (4-MTOB) and acetyl-CoA generates a 2-malate derivative that either enters the pathway for synthesis of C3-glucosinolates or undergoes additional extension reactions, which lead to C4- to C9-glucosinolates. Recent determination of the x-ray crystal structure of MAMS from Brassica juncea (Indian mustard) provided insight on the molecular evolution of MAMS, especially substrate specificity changes, from the leucine biosynthesis enzyme α-isopropylmalate synthase (IPMS) but left details of the reaction mechanism unanswered. Here we use the B. juncea MAMS2A (BjMAMS2A) isoform to analyze the kinetic and catalytic mechanism of this enzyme. Initial velocity studies indicate that MAMS follows an ordered bi bi kinetic mechanism, which based on the x-ray crystal structure, involves binding of 4-MTOB followed by acetyl-CoA. Examination of the pH-dependence of kcat and kcat/Km are consistent with acid/base catalysis. Site-directed mutagenesis of three residues originally proposed to function in the reaction mechanism - Arg89 (R89A, R89K, R89Q), Glu227 (E227A, E227D, E227Q), and His388 (H388A, H388N, H388Q, H388D, and H388E) - showed that only two mutants (E227Q and H388N) retained activity. Based on available structural and biochemical data, a revised reaction mechanism for MAMS-catalyzed elongation of methionine-derived aliphatic glucosinolates is proposed, which is likely also conserved in IPMS from leucine biosynthesis in plants and microbes.

Integrated transcriptomic and miRNA-seq analysis of Pak-choi provides insight into the molecular mechanisms involved in the preservation of postharvest quality by white LED light irradiation

Low-intensity white light-emitting diode (LED) irradiation effectively delays postharvest senescence in pak-choi at 20 °C and 90 % relative humidity. In this study, RNA-seq and miRNA-seq analyses were conducted on samples collected at 0 d (initial sample) and 5 d (CK and LED-treated samples) to evaluate the regulatory effects of white LED irradiation on miRNA. The resulting data revealed a total of 23 differentially expressed miRNAs (DEmiRNAs) in the CK/LED group on 5 d of storage. LED irradiation induced the expression of AP2 family genes and the biosynthesis of aliphatic glucosinolates by modulating the level of bra-miR172 family miRNAs. LED irradiation also stimulated the expression of genes associated with the photosynthetic pathway in pak-choi and regulated biosynthesis of ascorbic acid and resistance-associated transcription factors by modulating the level of novel miRNAs. Furthermore, LED irradiation suppressed cellulase and polygalacturonase activity, and maintained the pectin content. These findings demonstrate the ability of white LED light irradiation to significantly delay the postharvest senescence process in pak-choi by modulating miRNA expression.

Integrative Analyses of Metabolites and Transcriptome Reveal the Metabolic Pattern of Glucosinolates in Potherb Mustard (Brassica juncea var. multiceps).

Potherb mustard (Brassica juncea var. multiceps) is one of the most commonly consumed leafy vegetable mustards, either fresh or in pickled form. It is rich in glucosinolates, whose hydrolyzed products confer potherb mustard's distinctive flavor and chemopreventive properties. In this study, the composition and content of glucosinolates, as well as the hydrolysis pattern of sinigrin were investigated in potherb mustard leaves of different varieties. Variations in the glucosinolate profile and accumulation were observed among the potherb mustard varieties studied, with sinigrin being the predominant one in all varieties, accounting for 81.55% to 97.27%. Sinigrin tended to be hydrolyzed to isothiocyanate (ITC) rather than epithionitrile (EPN) in potherb mustard, while 3-butenyl nitrile (SIN-NIT) could be hardly detected. Transcriptome analysis revealed a higher expression level of numerous genes involved in aliphatic glucosinolate biosynthesis in X11 compared to X57, corresponding to the higher aliphatic glucosinolate accumulation in X11 (91.07 µmol/g) and lower level in X57 (25.38 µmol/g). ESM1 is known to repress nitrile formation and favor isothiocyanate production during glucosinolate hydrolysis. In this study, all four ESM1s showed a higher expression level in X11 compared to X57, which may determine the hydrolysis pattern of sinigrin in potherb mustard. Altogether, our findings shed light on the glucosinolate metabolic pattern in potherb mustard, which will also facilitate the engineering of metabolic pathways at key checkpoints to enhance bioactive compounds for tailored flavor or pharmaceutical needs.

Decoding comparative taste and nutrition regulation in Chinese cabbage via integrated metabolome and transcriptome analysis

Chinese cabbage (Brassica rapa L. ssp. pekinensis) is a widely consumed leafy vegetable known for its various health-beneficial nutrients. Caixin (ET and JY) represent distinct cultivars of Chinese cabbage that exhibit differential consumer preference attributed to variations in taste and nutritional content, with ET being characterized as sweeter and more nutritionally superior compared to JY. However, limited research has been conducted to explore regulation of flavor and nutrition-related quality traits in Chinese cabbage. In this pioneer study, comprehensive trans-meta-analysis was used to compare the metabolic and molecular underpinnings behind unique taste and nutritional profiles of ET and JY. 8-Methylsulfonyloctyl glucosinolates and Uridine 5′-diphospho-D-glucose exhibited the highest correlation coefficient in Pearson meta–meta-association, which modulate flavor and nutrition processes. While DAMs primarily featured L-Homomethionine, saccharic acid, 1,6-Di-O-caffeoyl-β-D-glucose, and Rutin, with notable variations in expression between ET and JY. Conspicuously, DEGs encoding structural enzymes i.e. Glucosinolates (MAM, CYP, UGT), flavonoids (CHS, CHI, F3H) and sucrose (SPS, SPP, SUS) synthases were identified as key players in nutrient and flavor production. Multi-omics conjoint analysis revealed that saccharides, amino acids, ascorbates, flavonoids, organic acids and vitamins were positively correlated with taste and nutrition, and were found to be overexpressed in ET. While aliphatic glucosinolates were abundant in JY compared to ET, they might play a critical role in regulating quality traits. Besides, HPLC and RT-qPCR corroborated multi-omics data reliability. These findings offer novel insights into the mechanisms governing the regulation of taste and nutritional levels in Chinese cabbage.

NAD+ deficiency primes defense metabolism via 1O2-escalated jasmonate biosynthesis in plants

Nicotinamide adenine dinucleotide (NAD+) is a redox cofactor and signal central to cell metabolisms. Disrupting NAD homeostasis in plant alters growth and stress resistance, yet the underlying mechanisms remain largely unknown. Here, by combining genetics with multi-omics, we discover that NAD+ deficiency in qs-2 caused by mutation in NAD+ biosynthesis gene-Quinolinate Synthase retards growth but induces biosynthesis of defense compounds, notably aliphatic glucosinolates that confer insect resistance. The elevated defense in qs-2 is resulted from activated jasmonate biosynthesis, critically hydroperoxidation of α-linolenic acid by the 13-lipoxygenase (namely LOX2), which is escalated via the burst of chloroplastic ROS-singlet oxygen (1O2). The NAD+ deficiency-mediated JA induction and defense priming sequence in plants is recapitulated upon insect infestation, suggesting such defense mechanism operates in plant stress response. Hence, NAD homeostasis is a pivotal metabolic checkpoint that may be manipulated to navigate plant growth and defense metabolism for stress acclimation.

UV-B irradiation enhances the accumulation of beneficial glucosinolates induced by melatonin in Chinese kale sprout

Cruciferous sprout is a new form of vegetable product rich in bioactive compounds, especially glucosinolates. Previous studies have focused on increasing the accumulation of glucosinolates in cruciferous sprouts by applying different chemical regulators, with a particular focus on their contribution to nutritional quality and health benefits. Nevertheless, the effects of melatonin and UV-B irradiation on glucosinolate biosynthesis remain unclear. In this study, it was found that changes in melatonin concentrations significantly affected the contents of individual as well as total aliphatic and indolic glucosinolates. The 5 μmol · L−1 melatonin was decided as the optimum concentration that could increase the content of beneficial glucosinolates including glucoraphanin and 4-methoxy glucobrassicin in Chinese kale sprouts. Notably, the enhancement of glucosinolate accumulation by melatonin treatment could be further amplified by UV-B irradiation. Furthermore, our results showed that R2R3-MYB transcription factor BoaMYB28 and BoaMYB51, which are central regulators of aliphatic and indolic glucosinolate biosynthesis respectively, were both involved in the regulation of glucosinolate biosynthesis by melatonin and UV-B irradiation. Additionally, the expression of glucosinolate biosynthetic genes, including BoaCYP79F1, BoaCYP83A1, BoaSUR1, BoaUGT74B1, BoaCYP79B2, BoaCYP79B3, and BoaCYP83B1 participated in the formation of core structures and BoaFMOGS-OX5, BoaAOP2, BoaCYP81F2, and BoaIGMT1 involved in the side-chain modification of aliphatic and indolic glucosinolate, was regulated by melatonin or UV-B irradiation. Taken together, these findings provide a potential strategy for improving the nutritional quality and resistance of Chinese kale sprouts.

ELONGATED HYPOCOTYL 5 interacts with HISTONE DEACETYLASE 9 to suppress glucosinolate biosynthesis in Arabidopsis.

Glucosinolates (GSLs) are defensive secondary metabolites produced by Brassicaceae species in response to abiotic and biotic stresses. The biosynthesis of GSL compounds and the expression of GSL-related genes are highly modulated by endogenous signals (i.e., circadian clocks) and environmental cues, such as temperature, light, and pathogens. However, the detailed mechanism by which light signaling influences GSL metabolism remains poorly understood. In this study, we found that a light-signaling factor, ELONGATED HYPOCOTYL 5 (HY5), was involved in the regulation of GSL content under light conditions in Arabidopsis (Arabidopsis thaliana). In hy5-215 mutants, the transcript levels of GSL pathway genes were substantially upregulated compared with those in wild-type plants. The content of GSL compounds was also substantially increased in hy5-215 mutants, whereas 35S::HY5-GFP/hy5-215 transgenic lines exhibited comparable levels of GSL-related transcripts and GSL content to those in WT plants. HY5 physically interacts with HISTONE DEACETYLASE9 (HDA9) and binds to the proximal promoter region of MYB29 and IMD1 to suppress aliphatic GSL biosynthetic processes. These results demonstrate that HY5 suppresses GSL accumulation during the daytime, thus properly modulating GSL content daily in Arabidopsis plants.

The RNA-Binding Protein BoRHON1 Positively Regulates the Accumulation of Aliphatic Glucosinolates in Cabbage.

Aliphatic glucosinolates are an abundant group of plant secondary metabolites in Brassica vegetables, with some of their degradation products demonstrating significant anti-cancer effects. The transcription factors MYB28 and MYB29 play key roles in the transcriptional regulation of aliphatic glucosinolates biosynthesis, but little is known about whether BoMYB28 and BoMYB29 are also modulated by upstream regulators or how, nor their gene regulatory networks. In this study, we first explored the hierarchical transcriptional regulatory networks of MYB28 and MYB29 in a model plant, then systemically screened the regulators of the three BoMYB28 homologs in cabbage using a yeast one-hybrid. Furthermore, we selected a novel RNA binding protein, BoRHON1, to functionally validate its roles in modulating aliphatic glucosinolates biosynthesis. Importantly, BoRHON1 induced the accumulation of all detectable aliphatic and indolic glucosinolates, and the net photosynthetic rates of BoRHON1 overexpression lines were significantly increased. Interestingly, the growth and biomass of these overexpression lines of BoRHON1 remained the same as those of the control plants. BoRHON1 was shown to be a novel, potent, positive regulator of glucosinolates biosynthesis, as well as a novel regulator of normal plant growth and development, while significantly increasing plants' defense costs.

Gregarines impact consumption and development but not glucosinolate metabolism in the mustard leaf beetle.

Gregarines are usually classified as parasites, but recent studies suggest that they should be viewed on a parasitism-mutualism spectrum and may even be seen as part of the gut microbiota of host insects. As such, they may also impact the consumption of their hosts and/or be involved in the digestion or detoxification of the host's diet. To study such effects of a gregarine species on those traits in its host, the mustard leaf beetle (Phaedon cochleariae) was used. This beetle species feeds on Brassicaceae plants that contain glucosinolates, which form toxic compounds when hydrolyzed by myrosinases. We cleaned host eggs from gametocysts and spores and reinfected half of the larvae with gregarines, to obtain gregarine-free (G-) and gregarine-infected (G+) larvae. Growth and food consumption parameters of these larvae were assessed by rearing individuals on watercress (Nasturtium officinale, Brassicaceae). A potential involvement of gregarines in the glucosinolate metabolism of P. cochleariae larvae was investigated by offering G- and G+ larvae leaf discs of watercress (containing mainly the benzenic 2-phenylethyl glucosinolate and myrosinases) or pea (Pisum sativum, Fabaceae, lacking glucosinolates and myrosinases) treated with the aliphatic 4-pentenyl glucosinolate or the indole 1-methoxy-3-indolylmethyl glucosinolate. Larval and fecal samples were analyzed via UHPLC-QTOF-MS/MS to search for breakdown metabolites. Larval development, body mass, growth rate and efficiency to convert food into body mass were negatively affected by gregarine infection while the pupal mass remained unaffected. The breakdown metabolites of benzenic and aliphatic glucosinolates were conjugated with aspartic acid, while those of the indole glucosinolate were conjugated with glutamic acid. Gregarine infection did not alter the larvae's ability to metabolize glucosinolates and was independent of plant myrosinases. In summary, some negative effects of gregarines on host performance could be shown, indicating parasitism. Future studies may further disentangle this gregarine-host relationship and investigate the microbiome potentially involved in the glucosinolate metabolism.

Effects of combined treatment of light quality and melatonin on health-promoting compounds in Chinese kale sprouts

Chinese kale sprouts have garnered attention owing to its rich health-promoting compounds. This study aimed to investigate the effects of different light qualities (white, blue, and red light) and melatonin (100 μmol L−1), both individually and in combination, on the growth and accumulation of health-promoting compounds in Chinese kale sprouts. Red light positively influenced sprout growth (compared with white light, plant height and fresh weight increased by 16.67 % and 4.87 %, respectively), and the red light + melatonin treatment further enhanced growth (compared with single red light, the plant height and fresh weight increased by 14.97 % and 12.29 %, respectively), while increasing glucosinolate accumulation through the up-regulation of glucosinolate biosynthetic genes (UGT74B1, CYP83B1, SOT18 and IGMT1). Conversely, blue light inhibited sprout growth, elevated the expression levels of PAL, CHS, CHI, GGP, and PAX, improved antioxidant levels, and accelerated the accumulation of aliphatic glucosinolates, reducing indolic glucosinolates. The blue light + melatonin treatment promoted the accumulation of sprout biomass and anthocyanins (11.91 % and 13.33 % higher than that of single blue light). The study unveiled various pathways influencing plant growth, development, and secondary metabolite accumulation, including plant circadian rhythms, ascorbate and aldarate metabolism, phenylpropanoid biosynthesis, and glucosinolate biosynthesis.

Growth conditions trigger genotype-specific metabolic responses that affect the nutritional quality of kale cultivars.

Kales (Brassica oleracea convar acephala) are fast-growing, nutritious leafy vegetables ideal for year-round indoor farming. However, selection of best cultivars for growth under artificial lighting necessitates a deeper understanding of leaf metabolism in different kale types. Here we examined a curly leaved cultivar Half Tall and a lacinato type cultivar Black Magic under moderate growth light (130 µmol photons m-1s-1/22°C) and high light (800 µmol photons m-1s-1/26°C) conditions. These conditions induced genotype-dependent differences in nutritionally important metabolites, especially anthocyanins and glucosinolates (GSLs), in the kale cultivars. In the pale green Half Tall, growth under high light conditions did not induce changes in either pigmentation or total GSL content. In contrast, the purple pigmentation of Black Magic intensified due to increased anthocyanin accumulation. Black Magic showed reduced amounts of indole GSLs and increased amounts of aliphatic GSLs under high light conditions, with notable cultivar-specific adjustments in individual GSL species. Correlation analysis of metabolite profiles suggested cultivar-specific metabolic interplay between serine biosynthesis and the production of indole GSLs. RNA sequencing identified candidate genes encoding metabolic enzymes and regulatory components behind anthocyanin and GSL biosynthesis. These findings improve the understanding of leaf metabolism and its effects on the nutritional quality of kale cultivars.

Modified atmosphere affects glucosinolate metabolism during postharvest storage of broccoli

Broccoli is a vegetable with a growing consumer demand worldwide due to its important nutritional properties, including high amounts of glucosinolates. However, this vegetable has a short postharvest life and quickly loses its organoleptic and nutritional quality. Modified atmosphere is one of the numerous methodologies used to delay deterioration during postharvest storage of broccoli heads. In this study, the effect of a modified atmosphere during postharvest storage of broccoli on glucosinolate metabolism was evaluated. Five glucosinolates were identified by using a UPLC system coupled to a mass spectrometer. We detected one aliphatic glucosinolate and four indolic glucosinolates, and their concentration was found to decrease during storage. The decrease in content was less marked, and in some cases, an increased level was observed in the treated samples. Moreover, the treatment made it possible to maintain higher expression (analyzed by real-time quantitative PCR) of genes linked to glucosinolate biosynthesis. We also detected an increased expression of some genes related to indolic glucosinolate biosynthesis. Overall, storage of broccoli in modified atmospheres allowed for maintaining better visual quality and higher levels of glucosinolates.

Exploring strategies to growth wild turnip sprouts as healthy food

BackgroundBrassicas (Brassicaceae) are recognized as excellent sources of nutrients and bioactive compounds. Among these, wild turnip (Brassica rapa L.), holds significant promising nutritional properties owed to its abundant glucosinolates and phenolic compounds. To enhance its potential values, the application of elicitors is crucial and good strategy prompting an enrichment in the concentration of phytochemicals, as well established in other relevant Brassicas, such as broccoli. While the responses triggered by certain elicitors such as salicylic acid, methyl jasmonate, or chitosan are widely documented, little is known about the impact of electrolyzed water, an economically viable elicitor. Through elicitation strategies, the aim of this work was to unravel insights into enhancing the phytochemical content of wild turnip sprouts for potential use as healthy food, comparing with well-studied broccoli as control of the experiments.ResultsOur findings revealed that wild turnip exhibited a notable higher glucosinolate (GSL) contents (487–712 mg 100 g−1 D.W.), than in broccoli sprouts. Furthermore, the use of electrolyzed water (2 vol.) boosted the accumulation of glucosinolates with significant increase up to twofolds the content. Specifically, treatments with salicylic acid (250 μM) and electrolyzed water (2 vol.) favored the significant increase of mainly aliphatic GSL (progoitrin, PRO; gluconapin, GNA; glucobrassicin, GBN). On the other hand, natural antioxidants such as of the characteristic acylated cyanidins present in wild turnip sprouts were not affected by the elicitor treatments, indicative of higher tolerance to oxidative stress in wild turnip.ConclusionsThese observations underlined the potential of using electrolyzed water in wild turnips as elicitor for GSL-enriched food ingredients. Further studies will be necessary to align with the broader goal of evaluating abiotic and biotic factors affecting the phytochemical composition in mature organs not only in germinating seeds and sprouts, for agricultural performance for quality and healthy foods purposes.Graphical

Unveiling Glucosinolate Diversity in Brassica Germplasm and In Silico Analysis for Determining Optimal Antioxidant Potential.

This study explored the glucosinolate (GSL) content in Brassica plants and utilized in silico analysis approach to assess their antioxidant capabilities. GSLs, present abundantly in Brassica vegetables, offer potential health advantages, including antioxidant effects. Employing Ultra-Performance Liquid Chromatography (UPLC) coupled with tandem mass spectrometry (MS/MS), major GSLs were identified in 89 accessions from diverse species and subspecies. Statistical analysis and principal component analysis unveiled significant GSL variation and potential correlations among the Brassica germplasms. This study unveils the dominance of aliphatic GSLs over aromatic and indolyl compounds in all the accessions. Notably, Gluconapin (GNA) (33,049.23 µmol·kg-1 DW), Glucobrassicanapin (GBN) (9803.82 µmol·kg-1 DW), Progoitrin (PRO) (12,780.48 µmol·kg-1 DW) and Sinigrin (SIN) (14,872.93 µmol·kg-1 DW) were the most abundant compounds across the analyzed accessions. Moreover, in silico docking studies predicted promising antioxidant activity by evaluating the interactions of each GSL with antioxidant enzymes. Specifically, Sinigrin and Gluconapin exhibited a notably weaker influence on antioxidant enzymes. This provides key insights into the antioxidant potential of Brassica germplasm and highlights the importance of in silico analysis for evaluating bioactive properties. In general, the results of this study could be utilized in breeding programs to maximize GSL levels and antioxidant properties in Brassica crops and for developing functional foods with enhanced health benefits.