Glucosinolate Composition Research Articles

Liquid chromatography–mass spectrometry coupled with multivariate analysis for the characterization and discrimination of extractable and nonextractable polyphenols and glucosinolates from red cabbage and Brussels sprout waste streams

Nonextractable polyphenol (NEP) fractions are usually ignored because conventional extraction methods do not release them from the plant matrix. In this study, we optimized the conditions for sonicated alkaline hydrolysis to the residues left after conventional polyphenol extraction of Brussels sprouts top (80°C, 4M NaOH, 30min) and stalks (60°C, 4M NaOH, 30min), and red cabbage waste streams (80°C, 4M NaOH, 45min) to release and characterize the NEP fraction. The NEP fractions of Brussels sprouts top (4.8±1.2mg gallic acid equivalents [GAE]/g dry waste) and stalks (3.3±0.2mg GAE/g dry waste), and red cabbage (11.5mg GAE/g dry waste) waste have significantly higher total polyphenol contents compared to their respective extractable polyphenol (EP) fractions (1.5±0.0, 2.0±0.0 and 3.7±0.0mg GAE/g dry waste, respectively). An LC-MS method combined with principal components analysis (PCA) and orthogonal partial least squares–discriminant analysis (OPLS–DA) was used to tentatively identify and discriminate the polyphenol and glucosinolate composition of the EP and NEP fractions. Results revealed that phenolic profiles of the EP and NEP fractions are different and some compounds are only found in either fraction in all of the plant matrices. This suggests the need to account both fractions when analyzing the polyphenol and glucosinolate profiles of plant matrices to attain a global view of their composition. This is the first report on the discrimination of the phenolic and glucosinolate profiles of the EP and NEP fractions using metabolomics techniques.

Impact of brassicaceous seed meals on the composition of the soil fungal community and the incidence of Fusarium wilt on chili pepper

Although brassicaceous seed meals (BSMs) have been evaluated for their ability to control various soil-borne diseases, establishing the relationship between disease severity and the soil fungal taxa specifically inhibited or enriched by the seed meal amendment has not been carefully assessed. The purpose of the present work was to elucidate the relationship between the glucosinolate concentration and composition in BSMs applied as soil amendments, the diversity and composition of the resulting soil fungal community, and the incidence of Fusarium wilt disease. These relationships were examined using chili pepper (Capsicum annuum ‘Ben Villalon’) as the bioassay plant grown in pots amended with different BSMs in the presence of the Fusarium wilt pathogen. We evaluated three BSMs differing in the species from which the seed meal was prepared and hence the glucosinolate content. These included Camelina sativa ‘Crantz’ (CAME), Brassica juncea ‘Pacific Gold’ (PG), and a mixture of PG and Sinapis alba cv. ‘IdaGold’ (IG) (PG+IG, 1:1 ratio). The effect of the BSMs on the fungal community was evaluated after the soil had been incubated for 25 days separately with each seed meal (incubated soil) and again after growing with chili pepper in pots for 35 days (rhizosphere soil). A soil treatment (no BSM amendment, comparable N, P, K added) was used as control. The composition of the soil fungal community in the incubated soil and the rhizosphere soil were examined using DNA based methods including quantitative real-time PCR and high throughput pyrosequencing. Our results indicated that the fungal abundances in the incubated soils were significantly increased by all BSM amendments, however the proliferation became less pronounced during the period of chili pepper growth. Of significance, the BSMs differed in their effect on the fungal community composition and on disease severity. For example, PG and PG+IG specifically enriched Chaetomium species, the abundance of which was negatively correlated with disease severity, and simultaneously specifically inhibited Hypocreales including the genus of Fusarium, the abundance of which was positively correlated with disease severity. PG and PG+IG exhibited good disease control efficacies in the pot experiment suggesting that 2-propenyl (allyl) glucosinolate, the primary glucosinolate component in the PG seed meal, played an important role in the changes in abundance of specific fungi during the 25-day incubation. CAME specifically enriched members of the Mortierellales, including the genus Mortierella, the abundance of which was not correlated disease severity. Moreover, our data indicated that BSM type was a more important determinant of fungal community composition than the plant host, given that the composition of the fungal communities after 35 days growth in the rhizosphere of chili pepper were not substantially different from the incubated soil communities before planting. Our results suggested that some species in the genus of Chaetomium may be important for disease management and deserved further evaluation as potential biocontrol agents.

Is there a trade-off between glucosinolate-based organic and inorganic defences in a metal hyperaccumulator in the field?

Several plant species are able to not only tolerate but also hyperaccumulate heavy metals in their aboveground tissues. Thus, in addition to secondary metabolites acting as organic defences, metal hyperaccumulators possess an elemental defence that can act as protection against antagonists. Whereas several laboratory studies have determined potential relationships or trade-offs between organic and inorganic defences, little is known about whether these traits are interconnected in the field and which factors determine the compositions of organic defences and elements of leaf tissues most. To target these questions, we collected young leaves of Arabidopsis halleri, a Brassicaceae capable of hyperaccumulating Cd and Zn, as well as soil samples in the field from 16 populations. We detected wide variation in the composition of glucosinolates-the characteristic secondary metabolites of this plant family-among plants, with two distinct chemotypes occurring. Distance-based redundancy analyses revealed that variation in glucosinolate composition was determined mainly by population affiliation and to a lesser degree by geographic distance. Likewise, elemental composition of the leaves was mainly influenced by the location at which samples were collected. Therefore, the particular abiotic and biotic conditions and potential genetic relatedness at a particular locality affect the plant tissue chemistry. A slight indication of a trade-off between glucosinolate-based organic and inorganic defences was found, but only in the less abundant chemotype. A large variation in defence composition and potential joint effects of different defences may be highly adaptive ways of protecting against a wide arsenal of biotic antagonists.

Variation of Glucosinolate Composition during Seedling and Growth Stages of Brassica rapa L. ssp. pekinensis

The objective of this study was to evaluate glucosinolate (GSL) profiles and variation of total and individual GSLs concentrations within seedling (0-14 days) and growth stages (0-15 weeks) of Korean Chinese cabbage (Brassica rapa L. ssp. pekinensis). Ten GSLs (progoitrin, glucoraphanin, glucoalyssin, gluconapin, glucobrassicanapin, 4-hydroxyglucobrassin, glucobrassicin, 4-methoxyglucobrassicin, neoglucobrassicin and gluconasturtiin) were identified from Korean Chinese cabbage. In general, total GSL content significantly decreased during seedling (from 92.89 to <TEX>$35.26{\mu}mol{\cdot}g^{-1}$</TEX> DW) and g rowth stages ( from 74.11 to <TEX>$1.97{\mu}mol{\cdot}g^{-1}$</TEX> DW). Gluconapin was the highest in seeds and in the germination period (<TEX>$73.1{\mu}mol{\cdot}g^{-1}$</TEX> DW) and declined gradually from 73 to 15% during seedling stages. The level of the major aliphatic GSLs, gluconapin and progoitrin, tended to decrease sharply, whereas levels of indolic GSLs (4-methoxyglucobrassicin, glucobrassicin) and aromatic GSLs (gluconasturtiin) were found to increase generally at the beginning of growth stages.

Identification and quantification of glucosinolate and flavonol compounds in rocket salad (Eruca sativa, Eruca vesicaria and Diplotaxis tenuifolia) by LC–MS: Highlighting the potential for improving nutritional value of rocket crops

Liquid chromatography mass spectrometry (LC–MS) was used to obtain glucosinolate and flavonol content for 35 rocket accessions and commercial varieties. 13 glucosinolates and 11 flavonol compounds were identified. Semi-quantitative methods were used to estimate concentrations of both groups of compounds. Minor glucosinolate composition was found to be different between accessions; concentrations varied significantly. Flavonols showed differentiation between genera, with Diplotaxis accumulating quercetin glucosides and Eruca accumulating kaempferol glucosides. Several compounds were detected in each genus that have only previously been reported in the other. We highlight how knowledge of phytochemical content and concentration can be used to breed new, nutritionally superior varieties. We also demonstrate the effects of controlled environment conditions on the accumulations of glucosinolates and flavonols and explore the reasons for differences with previous studies. We stress the importance of consistent experimental design between research groups to effectively compare and contrast results.

Metabolic Engineering of Aliphatic Glucosinolates in Hairy Root Cultures of Arabidopsis thaliana

Two cytochrome P450 proteins, CYP79F1 and CYP79F2, are involved in the biosynthesis of aliphatic glucosinolates (GSs) in brassicaceous species. In order to increase aliphatic GS levels in Arabidopsis thaliana hairy root cultures (HRCs) with the aim of biomanufacturing GSs, CYP79F1 and CYP79F2 from either Arabidopsis thaliana or Brassica rapa were first constitutively expressed in stably transformed Arabidopsis plants, and then HRC was induced by additional transformation with Agrobacterium rhizogenes. Gene expression levels and GS profiles were analyzed in HRC in order to validate the impact on aliphatic levels. To estimate the potency of gene transformation on GS content in HRC, GS levels were compared to levels in roots and leaves of transformed plants. According to the data obtained, short-chain aliphatic GSs in plants were raised in three generations after transformation, indicating that expression of transgenes was stable. After HRC induction, transcript levels of CYP79F1 and CYP79F2 rose and short-chain aliphatic GS levels increased by as much as 7-fold compared to the respective HRC wild-type control. However, when compared to levels present in leaves and roots of plants before HRC induction, aliphatic GS levels in HRC remained very low. In addition, expression of CYP79F1 and CYP79F2 also enhanced the content of indole GSs, mainly indol-3-ylmethyl GS and 4-hydroxy-indol-3-ylmethyl GS in HRC. The results presented provide basic information about GS biosynthesis in HRC of Arabidopsis thaliana compared to intact plants, which will help scientists to further optimize GS composition in HRC in the future.

Exogenous methyl jasmonate treatment increases glucosinolate biosynthesis and quinone reductase activity in kale leaf tissue.

Methyl jasmonate (MeJA) spray treatments were applied to the kale varieties ‘Dwarf Blue Curled Vates’ and ‘Red Winter’ in replicated field plantings in 2010 and 2011 to investigate alteration of glucosinolate (GS) composition in harvested leaf tissue. Aqueous solutions of 250 µM MeJA were sprayed to saturation on aerial plant tissues four days prior to harvest at commercial maturity. The MeJA treatment significantly increased gluconasturtiin (56%), glucobrassicin (98%), and neoglucobrassicin (150%) concentrations in the apical leaf tissue of these genotypes over two seasons. Induction of quinone reductase (QR) activity, a biomarker for anti-carcinogenesis, was significantly increased by the extracts from the leaf tissue of these two cultivars. Extracts of apical leaf tissues had greater MeJA mediated increases in phenolics, glucosinolate concentrations, GS hydrolysis products, and QR activity than extracts from basal leaf tissue samples. The concentration of the hydrolysis product of glucoraphanin, sulforphane was significantly increased in apical leaf tissue of the cultivar ‘Red Winter’ in both 2010 and 2011. There was interaction between exogenous MeJA treatment and environmental conditions to induce endogenous JA. Correlation analysis revealed that indole-3-carbanol (I3C) generated from the hydrolysis of glucobrassicin significantly correlated with QR activity (r = 0.800, P<0.001). Concentrations required to double the specific QR activity (CD values) of I3C was calculated at 230 µM, which is considerably weaker at induction than other isothiocyanates like sulforphane. To confirm relationships between GS hydrolysis products and QR activity, a range of concentrations of MeJA sprays were applied to kale leaf tissues of both cultivars in 2011. Correlation analysis of these results indicated that sulforaphane, NI3C, neoascorbigen, I3C, and diindolylmethane were all significantly correlated with QR activity. Thus, increased QR activity may be due to combined increases in phenolics (quercetin and kaempferol) and GS hydrolysis product concentrations rather than by individual products alone.

The hnRNP-Q protein LIF2 participates in the plant immune response.

Eukaryotes have evolved complex defense pathways to combat invading pathogens. Here, we investigated the role of the Arabidopsis thaliana heterogeneous nuclear ribonucleoprotein (hnRNP-Q) LIF2 in the plant innate immune response. We show that LIF2 loss-of-function in A. thaliana leads to changes in the basal expression of the salicylic acid (SA)- and jasmonic acid (JA)- dependent defense marker genes PR1 and PDF1.2, respectively. Whereas the expression of genes involved in SA and JA biosynthesis and signaling was also affected in the lif2-1 mutant, no change in SA and JA hormonal contents was detected. In addition, the composition of glucosinolates, a class of defense-related secondary metabolites, was altered in the lif2-1 mutant in the absence of pathogen challenge. The lif2-1 mutant exhibited reduced susceptibility to the hemi-biotrophic pathogen Pseudomonas syringae and the necrotrophic ascomycete Botrytis cinerea. Furthermore, the lif2-1 sid2-2 double mutant was less susceptible than the wild type to P. syringae infection, suggesting that the lif2 response to pathogens was independent of SA accumulation. Together, our data suggest that lif2-1 exhibits a basal primed defense state, resulting from complex deregulation of gene expression, which leads to increased resistance to pathogens with various infection strategies. Therefore, LIF2 may function as a suppressor of cell-autonomous immunity. Similar to its human homolog, NSAP1/SYNCRIP, a trans-acting factor involved in both cellular processes and the viral life cycle, LIF2 may regulate the conflicting aspects of development and defense programs, suggesting that a conserved evolutionary trade-off between growth and defense pathways exists in eukaryotes.

The influence of selenium addition during germination of Brassica seeds on health-promoting potential of sprouts

The correlation among selenium uptake, the content of bioactive compounds in sprouts, and biological activities triggered in cultured human cells by sprout extracts was investigated. Seeds of Brassica crops and rye were treated with SeO2 water solution. The selenium levels in sprouts increased from 1.0–4.1 to 53.3–382 μg/g dw with no influence on plant physiology according to the indices used. Neither the composition of glucosinolates (GL) in Brassica sprouts nor the myrosinase activity nor the composition of GL breakdown lipophilic products were significantly affected. In all Brassica sprouts, conversion to health-promoting isothiocyanates (ITC) and indoles corresponded to only 1% of total GLs. Low ITC concentration may explain observed lack of induction of glutathione S-transferases (GST) and quinone oxidoreductase (NQO) detoxifying enzymes in HT29 cells exposed to sprout extracts. The insignificant impact on cell growth and genome function suggests that Brassica sprouts may be safe vehicle of selenium to combat its dietary deficiency.

Functional identification of genes responsible for the biosynthesis of 1-methoxy-indol-3-ylmethyl-glucosinolate in Brassica rapa ssp. chinensis.

BackgroundBrassica vegetables contain a class of secondary metabolites, the glucosinolates (GS), whose specific degradation products determine the characteristic flavor and smell. While some of the respective degradation products of particular GS are recognized as health promoting substances for humans, recent studies also show evidence that namely the 1-methoxy-indol-3-ylmethyl GS might be deleterious by forming characteristic DNA adducts. Therefore, a deeper knowledge of aspects involved in the biosynthesis of indole GS is crucial to design vegetables with an improved secondary metabolite profile.ResultsInitially the leafy Brassica vegetable pak choi (Brassica rapa ssp. chinensis) was established as suitable tool to elicit very high concentrations of 1-methoxy-indol-3-ylmethyl GS by application of methyl jasmonate. Differentially expressed candidate genes were discovered in a comparative microarray analysis using the 2 × 104 K format Brassica Array and compared to available gene expression data from the Arabidopsis AtGenExpress effort. Arabidopsis knock out mutants of the respective candidate gene homologs were subjected to a comprehensive examination of their GS profiles and confirmed the exclusive involvement of polypeptide 4 of the cytochrome P450 monooxygenase subfamily CYP81F in 1-methoxy-indol-3-ylmethyl GS biosynthesis. Functional characterization of the two identified isoforms coding for CYP81F4 in the Brassica rapa genome was performed using expression analysis and heterologous complementation of the respective Arabidopsis mutant.ConclusionsSpecific differences discovered in a comparative microarray and glucosinolate profiling analysis enables the functional attribution of Brassica rapa ssp. chinensis genes coding for polypeptide 4 of the cytochrome P450 monooxygenase subfamily CYP81F to their metabolic role in indole glucosinolate biosynthesis. These new identified Brassica genes will enable the development of genetic tools for breeding vegetables with improved GS composition in the near future.

秋から冬に市販される日本産アブラナ科野菜の グルコシノレート組成および含有量

Brassicaceae vegetables contain glucosinolates, and have been known to contribute to the promotion of health in human beings. The objective of this study was to identify the composition and content of glucosinolates, and to identify the distribution of ω-methylsulfinyl, phenetyl, and indolyl-3-methyl glucosinolates, which are the precursors of isothiocyanates which induce phase Ⅱ enzymes and/or inhibit phase Ⅰ enzymes, in the 15 species of Brassicaceae vegetables which were har vested during autumn and winter in Japan.Glucosinolate profiles were investigated by LC-MS.Twenty-five species of glucosinolates were identified (aliphatic 18, aromatic 3, indole 4). 4-methylsulfinylbutyl glucosinolate was included in broccoli sprouts ( 111.15±15.46μmol・gDW-1 ), broccoli ( 10.45±5.05 ), cabbage ( 5.05±5.82 ), and rocket salad ( 4.15±1.83 ). 5-methylsulfinylpentyl glucosinolate was included in tur nip leaves ( 2.96±1.39 ) and field mustard ( nabana ) ( 2.10±1.73 ). In watercress, 6-methylsulfinylhexyl ( 2.96±0.98 ), 7-methylsulfinylheptyl ( 25.08±5.20 ), and 8-methylsulfinyloctyl glucosinolate ( 4.24±3.07 ) were included at a higher content than in any other vegetables. Phenethyl glucosinolate was included in many kinds of Blassica vegetables. These were watercress ( 30.03±8.88 ), tur nip rapa ( 5.64±1.86 ) and leaves ( 2.42±0.17 ), field mustard ( 1.73±0.51 ), broccoli sprouts ( 1.47±0.05 ), and komatsuna ( 1.30±1.12 ). Indolyl-3-methyl glucosinolate was included in many vegetables excluding Japanese radish and rocket salad.

Influence of Seasonal Variation and Methyl Jasmonate Mediated Induction of Glucosinolate Biosynthesis on Quinone Reductase Activity in Broccoli Florets

Methyl jasmonate spray treatments (250 μM) were utilized to alter glucosinolate composition in the florets of the commercial broccoli F1 hybrids 'Pirate', 'Expo', 'Green Magic', 'Imperial', and 'Gypsy' grown in replicated field plantings in 2009 and 2010. MeJA treatment significantly increased glucoraphanin (11%), gluconasturtiin (59%), and neoglucobrassicin (248%) concentrations and their hydrolysis products including sulforaphane (152%), phenethyl isothiocyanate (318%), N-methoxyindole-3-carbinol (313%), and neoascorbigen (232%) extracted from florets of these genotypes over two seasons. Increased quinone reductase (QR) activity was significantly correlated with increased levels of sulforaphane, N-methoxyindole-3-carbinol, and neoascorbigen. Partitioning experiment-wide trait variances indicated that the variability in concentrations of sulforaphane (29%), neoascorbigen (48%), and QR activity (72%) was influenced by year-associated weather variables, whereas variation in neoglucobrassicin (63%) and N-methoxyindole-3-carbinol (46%) concentrations was primarily attributed to methyl jasmonate treatment. These results suggest that methyl jasmonate treatment can enhance QR inducing activity by increased hydrolysis of glucoraphanin into sulforaphane and the hydrolysis products of neoglucobrassicin.

Four genes encoding MYB28, a major transcriptional regulator of the aliphatic glucosinolate pathway, are differentially expressed in the allopolyploid Brassica juncea

Glucosinolates are Capparales-specific secondary metabolites that have immense potential in human health and agriculture. Unlike Arabidopsis thaliana, our knowledge about glucosinolate regulators in the Brassica crops is sparse. In the current study, four MYB28 homologues were identified (BjuMYB28-1,-2,-3,-4) from the polyploid Brassica juncea, and the effects of allopolyploidization on the divergence of gene sequence, structure, function, and expression were assessed. The deduced protein sequences of the four BjuMYB28 genes showed 76.1–83.1% identity with the Arabidopsis MYB28. Phylogenetic analysis revealed that the four BjuMYB28 proteins have evolved via the hybridization and duplication processes forming the B. juncea genome (AABB) from B. rapa (AA) and B. nigra (BB), while retaining high levels of sequence conservation. Mutant complementation and over-expression studies in A. thaliana showed that all four BjuMYB28 genes encode functional MYB28 proteins and resulted in similar aliphatic glucosinolate composition and content. Detailed expression analysis using qRT-PCR assays and promoter-GUS lines revealed that the BjuMYB28 genes have both tissue- and cell-specific expression partitioning in B. juncea. The two B-genome origin BjuMYB28 genes had more abundant transcripts during the early stages of plant development than the A-genome origin genes. However, with the onset of the reproductive phase, expression levels of all four BjuMYB28 increased significantly, which may be necessary for producing and maintaining high amounts of aliphatic glucosinolates during the later stages of plant development. Taken together, our results suggest that the four MYB28 genes are differentially expressed and regulated in B. juncea to play discrete though overlapping roles in controlling aliphatic glucosinolate biosynthesis.

Verticillium suppression is associated with the glucosinolate composition of Arabidopsis thaliana leaves.

The soil-borne fungal pathogen Verticillium longisporum is able to penetrate the root of a number of plant species and spread systemically via the xylem. Fumigation of Verticillium contaminated soil with Brassica green manure is used as an environmentally friendly method for crop protection. Here we present a study focused on the potential role of glucosinolates and their breakdown products of the model plant Arabidopsis thaliana in suppressing growth of V. longisporum. For this purpose we analysed the glucosinolate composition of the leaves and roots of a set of 19 key accessions of A. thaliana. The effect of volatile glucosinolate hydrolysis products on the in vitro growth of the pathogen was tested by exposing the fungus to hydrated lyophilized plant tissue. Volatiles released from leaf tissue were more effective than from root tissue in suppressing mycelial growth of V. longisporum. The accessions varied in their efficacy, with the most effective suppressing mycelial growth by 90%. An analysis of glucosinolate profiles and their enzymatic degradation products revealed a correlation between fungal growth inhibition and the concentration of alkenyl glucosinolates, particularly 2-propenyl (2Prop) glucosinolate, respectively its hydrolysis products. Exposure of the fungus to purified 2Prop glucosinolate revealed that its suppressive activity was correlated with its concentration. Spiking of 2Prop glucosinolate to leaf material of one of the least effective A. thaliana accessions led to fungal growth suppression. It is suggested that much of the inhibitory effect observed for the tested accessions can be explained by the accumulation of 2Prop glucosinolate.

Heterodera schachtii nematodes interfere with aphid-plant relations on Brassica oleracea.

Aboveground and belowground herbivore species modify plant defense responses differently. Simultaneous attack can lead to non-additive effects on primary and secondary metabolite composition in roots and shoots. We previously found that aphid (Brevicoryne brassicae) population growth on Brassica oleracea was reduced on plants that were infested with nematodes (Heterodera schachtii) prior (4 weeks) to aphid infestation. Here, we examined how infection with root-feeding nematodes affected primary and secondary metabolites in the host plant and whether this could explain the increase in aphid doubling time from 3.8 to 6.7 days. We hypothesized that the effects of herbivores on plant metabolites would depend on the presence of the other herbivore and that nematode-induced changes in primary metabolites would correlate with reduced aphid performance. Total glucosinolate concentration in the leaves was not affected by nematode presence, but the composition of glucosinolates shifted, as gluconapin concentrations were reduced, while gluconapoleiferin concentrations increased in plants exposed to nematodes. Aphid presence increased 4-methoxyglucobrassicin concentrations in leaves, which correlated positively with the number of aphids per plant. Nematodes decreased amino acid and sugar concentrations in the phloem. Aphid population doubling time correlated negatively with amino acids and glucosinolate levels in leaves, whereas these correlations were non-significant when nematodes were present. In conclusion, the effects of an herbivore on plant metabolites were independent of the presence of another herbivore. Nematode presence reduced aphid population growth and disturbed feeding relations between plants and aphids.Electronic supplementary materialThe online version of this article (doi:10.1007/s10886-013-0338-4) contains supplementary material, which is available to authorized users.

Peculiar properties of glucosinolate accumulation in the Brassicaceae family

The total content and the composition of the constituents of glucosinolates were analyzed in 51 samples of 6 species of 5 genera of the Brassicaceae family. The twenty-one component of the profile of glucosinolates, including fifteen aliphatic glucosinolates, four insole glucosinolates, and two aromatic glucosinolates, were revealed. The wide potential of variability of the constituent composition of glucosinolates was found, which allows to use the cabbage plants to various purposes, such as a valuable foodstuff and for fumigation of soils. All studied samples of Sinapsis alba L. and six samples of Brassica juncea Czen, which possess a high (more than 40 I¼mol/g) concentration of sinalbin and sinigrin, correspondingly, are recommended for biofumigation. It was revealed that the glucosinolates of Brassica rapa L. contain 17 constituents. For the first time, samples of the variety that have an increased value of constituent composition of glucosinolates for balanced food of people were found. These varieties are recommended for use in breeding, including for medical purposes, and for the completion of assortment of cabbage vegetables.

Evaluation of Glucosinolate Variation in a Collection of Turnip (Brassica rapa) Germplasm by the Analysis of Intact and Desulfo Glucosinolates

Glucosinolates (GLS) are secondary metabolites occurring in cruciferous species. These compounds are important for plant defense, human health, and the characteristic flavor of Brassica vegetables. In this study, the GLS in tubers from a collection of 48 turnip ( Brassica rapa ) accessions from different geographic origin were analyzed. Two different methods were used: desulfo GLS were analyzed by high-performance liquid chromatography with a photodiode array detector, and intact GLS were analyzed by accurate mass liquid chromatography-mass spectrometry. For most GLS, desulfo and intact signals correlated well, and the analytical reproducibility for individual GLS was similar for both methods. A total of 11 different GLS was monitored in the turnip tubers, through both intact and desulfo GLS analysis methods. Four clusters of accessions could be clearly distinguished based on GLS composition of the turnip tuber. Clustering based on tuber GLS differed markedly from a previously published clustering based on leaf GLS.

Variation in glucosinolates in pak choi cultivars and various organs at different stages of vegetative growth during the harvest period.

Glucosinolates (GSs) play an important role in plant defense systems and human nutrition. We investigated the content and composition of GSs in the shoots and roots of seven cultivars of pak choi. We found that 'Si Yue Man' had the highest total and aliphatic GS contents in the shoots and the highest benzenic GS content in the roots, 'Shanghai Qing' contained the highest amounts of benzenic and total GS contents in the roots, while 'Nanjing Zhong Gan Bai' had the lowest benzenic, indole, and total GS contents in both the shoots and roots. Therefore, the 'Si Yue Man' cultivar appears to be a good candidate for future breeding. Variation between the shoots and roots was also examined, and a significant correlation among the total, aliphatic, and some individual GSs was found, which is of value in agricultural breeding. GS concentrations of the leaf, petiole, and root increased dramatically during the period of rapid growth of the dry matter of the plant 10 to 20 d after transplantation, reaching peak values on Day 20 and decreasing on Day 25. We conclude that the pak choi should be harvested and consumed from 20 to 25 d after transplantation to take advantages of the high GS content in the plant.

Genotypic Variation of the Glucosinolate Profile in Pak Choi (Brassica rapa ssp. chinensis)

Thirteen different pak choi (Brassica rapa ssp. chinensis) cultivars were characterized regarding their glucosinolate profile analyzed by HPLC-DAD-MS. The identified glucosinolates were subjected to principal component analysis, and three distinct groups of pak choi sprouts were identified. Group differences were marked mainly by variations in the aliphatic glucosinolate profile such as differing levels of 3-butenyl glucosinolate and 2-hydroxy-3-butenyl glucosinolate as well as by their varying proportional ratios. In addition, the three groups of pak choi sprouts varied by the presence or absence of 2-hydroxy-4-pentenyl glucosinolate and in level and composition of butyl glucosinolates. This classification is reflected by relative mRNA expression level of 2-oxoacid-dependent dioxygenase. As in sprouts, the major glucosinolates in mature leaves were found to be the aliphatic glucosinolates. However, unlike in sprouts, an additional aliphatic glucosinolate, 5-methylsulfinylpentyl glucosinolate, was detected as characteristic ontogenetic variation in mature leaves in 12 of the 13 pak choi cultivars analyzed.

Comparative Fingerprint of Glucosinolates from Brassica Vegetables Using HATR/FT-MIR Spectroscopy

Glucosinolates (β-thioglucoside-N-hydroxysulphates) are very important plant secondary metabolites containing a β-D-glucopyranose residue linked to a sulfur atom (i), or to a (Z)-Nhydroximinosulfate ester (ii) or a variable R group (iii) with different side-chain substituents which give their structural diversity.  The objective of the present research was to compare the fingerprint of 9 standard pure glucosinolates and Brassica vegetables extracts of broccoli, cauliflower and kohlrabi, cultivated in North-West of Romania, using the Fourier Transform Infrared Spectroscopy (FTIR). The FTIR fingerprint was recorded for both, desulpho - standards of glucosinolates (sinigrin, gluconapin, progoitrin, glucoiberin, glucoraphanin, glucotropaeolin and glucobrassicin) and intact glucosinolates (sinigrin and glucotropaeolin). The extraction of glucosinolates was made according to the EU official method (EEC Regulation N. 1864/90). The FTIR spectra for standards and Brassica dried extracts were recorded in the MIR region, from 4000 and 900 cm-1. The results obtained show that HATR/FT-MIR spectroscopy can be used as a fast method for the quantification of total glucosinolates considering the IR absorption at 800   cmor the region area of 750-900 cm-1, is the most suitable. The HATR/FT-MIR is non-destructive, cheap and fast method to fingerprint, to predict and to quantify the glucosinolate composition of Brassica vegetables. Â