Levels Of Glucosinolates Research Articles

A Different Pattern of Production and Scavenging of Reactive Oxygen Species in Halophytic Eutrema salsugineum (Thellungiella salsuginea) Plants in Comparison to Arabidopsis thaliana and Its Relation to Salt Stress Signaling.

Isolated thylakoids from halophytic Eutrema salsugineum (Thellungiella salsuginea) produces more H2O2 in comparison to glycophytic Arabidopsis thaliana. The first objective of this study was to verify whether this feature is relevant also to the intact chloroplasts and leaves. Enhanced H2O2 levels in chloroplasts and leaves of E. salsugineum were positively verified with several methods (electron microscopy, staining with Amplex Red and with diaminobenzidine). This effect was associated with a decreased ratio of /H2O2 in E. salsugineum in comparison to A. thaliana as detected by electron paramagnetic resonance method. As a next step, we tested how this specific ROS signature of halophytic species affects the antioxidant status and down-stream components of ROS signaling. Comparison of enzymatic antioxidants revealed a decreased activity of ascorbate peroxidase (APX), enhanced activity of glutathione peroxidase, and the presence of thylakoid-bound forms of iron superoxide dismutase (FeSOD) and APX in E. salsugineum. These cues were, however, independent from application of salt stress. The typical H2O2-dependent cellular responses, namely the levels of glucosinolates and stress-related hormones were determined. The total glucosinolate content in E. salsugineum water-treated leaves was higher than in A. thaliana and increased after salinity treatment. Treatment with salinity up-regulated all of tested stress hormones, their precursors and catabolites [abscisic acid (ABA), dihydrophaseic acid, phaseic acid, 1-aminocyclopropane-1-carboxylic acid, salicylic acid, jasmonic acid, cis-(+)-12-oxo-phytodienoic acid and jasmonoyl-L-isoleucine] in A. thaliana, whereas in E. salsugineum only a stimulation in ethylene synthesis and ABA catabolism was noted. Obtained results suggest that constitutively enhanced H2O2 generation in chloroplasts of E. salsugineum might be a crucial component of stress-prepardeness of this halophytic species. It shapes a very efficient antioxidant protection (in which glucosinolates might play a specific role) and a fine tuning of hormonal signaling to suppress the cell death program directed by jasmonate pathway.

Ecotypic differentiation of two sympatric chemotypes of Barbarea vulgaris (Brassicaceae) with different biotic resistances

Evolution of ecotypic differentiation and maintenance of divergence in sympatry is more likely if populations occupy different habitats. Two genetically divergent chemotypes of Barbarea vulgaris (Brassicaceae) with contrasting insect and disease resistances (G- and P-type) occupy different geographical ranges in Eurasia but co-occur in Denmark. Here, they grow mostly in separate populations, posing the question why they have not merged. In a 2-year reciprocal transplant experiment, we tested whether the two plant types prefer different habitats and are adapted to these, possibly influenced by selection by herbivores. Vegetation and soil analyses indicated that the G-type occurs in slightly drier, less productive and more alkaline sites than the P-type. Plants planted at sites of their own chemotype had a higher biomass in the first year than plants of the non-resident chemotype, but were more damaged by beetle herbivory. This suggests that herbivores have adapted genetically or plastically to the resident chemotype. G-plants were less damaged by molluscs than P-plants, which may be caused by their content of saponins or glucosinolates. Levels of glucosinolates in siliques were higher in G-plants, but varied strongly among sites. Survival, reproduction and biomass in the second year did not differ between plants growing at sites of their own chemotype and plants of the other chemotype. Thus, the two chemotypes of B. vulgaris are adapted to different habitats to some extent, which could contribute to maintain their differentiation in sympatry. Herbivory by some insects, however, may counteract this.

Effect of growth temperature on glucosinolate profiles in Arabidopsis thaliana accessions

Glucosinolates are plant secondary metabolites with important roles in plant defence against pathogens and pests and are also known for their health benefits. Understanding how environmental factors affect the level and composition of glucosinolates is therefore of importance in the perspective of climate change. In this study we analysed glucosinolates in Arabidopsis thaliana accessions when grown at constant standard (21 °C), moderate (15 °C) and low (9 °C) temperatures during three generations. In most of the tested accessions moderate and pronounced chilling temperatures led to higher levels of glucosinolates, especially aliphatic glucosinolates. Which temperature yielded the highest glucosinolate levels was accession-dependent. Transcriptional profiling revealed also accession-specific gene responses, but only a limited correlation between changes in glucosinolate-related gene expression and glucosinolate levels. Different growth temperatures in one generation did not consistently affect glucosinolate composition in subsequent generations, hence a clear transgenerational effect of temperature on glucosinolates was not observed.

Metabolic Profiling in Chinese Cabbage (Brassica rapa L. subsp. pekinensis) Cultivars Reveals that Glucosinolate Content Is Correlated with Carotenoid Content.

A total of 38 bioactive compounds, including glucosinolates, carotenoids, tocopherols, sterols, and policosanols, were characterized from nine varieties of Chinese cabbage (Brassica rapa L. subsp. pekinensis) to determine their phytochemical diversity and analyze their abundance relationships. The metabolite profiles were evaluated with principal component analysis (PCA), Pearson correlation analysis, and hierarchical clustering analysis (HCA). PCA and HCA identified two distinct varieties of Chinese cabbage (Cheonsangcheonha and Waldongcheonha) with higher levels of glucosinolates and carotenoids. Pairwise comparisons of the 38 metabolites were calculated using Pearson correlation coefficients. The HCA, which used the correlation coefficients, clustered metabolites that are derived from closely related biochemical pathways. Significant correlations were discovered between chlorophyll and carotenoids. Additionally, aliphatic glucosinolate and carotenoid levels were positively correlated. The Cheonsangcheonha and Waldongcheonha varieties appear to be good candidates for breeding because they have high glucosinolate and carotenoid levels.

The simultaneous inducibility of phytochemicals related to plant direct and indirect defences against herbivores is stronger at low elevation

Summary Ecological theory indicates that warmer and more stable climates should result in stronger biotic interactions. Therefore, plant species growing at lower elevations and experiencing greater herbivore pressure should invest in higher levels of defences than those at higher elevations. Nonetheless, there are a number of studies that have found no effect of elevational gradients on plant defensive traits. Several factors might explain the lack of consistency for the altitude–defence relationships, including (i) the reduction of all defensive traits into one measure of resistance; (ii) not considering plant defence as the simultaneous expression of several defensive traits; and (iii) not considering the relative influence of biotic (e.g. herbivory) and abiotic (e.g. climate and soil conditions) factors associated with the ecological gradient. Here, we present a comprehensive test of the effects of elevation and its associated biotic and abiotic factors on the individual and simultaneous expression of constitutive direct and indirect defences and their inducibility (i.e. expression of defences after herbivore attack). Specifically, we estimated climatic and soil variables and measured herbivore damage and constitutive and jasmonic acid‐induced glucosinolate levels in the leaves as a proxy for direct defences, and volatile emission as a proxy for indirect defences in 16 Cardamine species naturally growing along the steep elevational gradient of the Alps. Within a phylogenetic comparative framework, we found that species growing at lower elevations invested more in the simultaneous inducibility of both direct and indirect defences, whereas species growing at higher elevations invested more in constitutive direct defences. Although we found strong elevational gradients in herbivory and climatic and soil variables, these biotic and abiotic factors only partially explained elevational patterns in plant defences. Synthesis. These results highlight that the complex regulation of multiple defence traits strongly vary across elevational gradients and build towards a better understanding of the multiple mechanisms underlying trait evolution and species interactions along ecological gradients.

Modification of glucosinolates in turnip greens (Brassica rapa subsp. rapa L.) subjected to culinary heat processes

ABSTRACTThe consumption of Brassica vegetables has been related to improved health benefits due to their phytochemical components, such as glucosinolates, that induce a variety of physiological functions. Glucosinolate levels can be affected when they are submitted to heat treatments before consumption. This paper investigates, by an HPLC-DAD method, the effect of three cooking treatments on the nutritional quality of turnip greens. Fresh turnip leaves were homogenized with sand and Milli-Q water and centrifuged. They remained there for 3 h for natural autolysis. Samples, fresh and processed, were extracted with dichloromethane; the organic extract had been evaporated to dryness, was dissolved in acetonitrile and injected into the chromatograph. Eight compounds were identified: allyl-isothiocyanate, erucin, sulforaphane, iberin, napin, goitrin, benzyl- isothiocyanate and phenethyl-isothiocyanate. Napin was the major compound in all samples followed by goitrin. The best treatment is steam cooking, followed by pressure-cooking, while the boiling treatment produced a 60% loss.

Diversity of Kale (Brassica oleracea var. sabellica): Glucosinolate Content and Phylogenetic Relationships.

Recently, kale has become popular due to nutritive components beneficial for human health. It is an important source of phytochemicals such as glucosinolates that trigger associated cancer-preventive activity. However, nutritional value varies among glucosinolates and among cultivars. Here, we start a systematic determination of the content of five glucosinolates in 25 kale varieties and 11 non-kale Brassica oleracea cultivars by HPLC-DAD-ESI-MS(n) and compare the profiles with results from the analysis of SNPs derived from a KASP genotyping assay. Our results demonstrate that the glucosinolate levels differ markedly among varieties of different origin. Comparison of the phytochemical data with phylogenetic relationships revealed that the common name kale refers to at least three different groups. German, American, and Italian kales differ morphologically and phytochemically. Landraces do not show outstanding glucosinolate levels. Our results demonstrate the diversity of kale and the importance of preserving a broad genepool for future breeding purposes.

Aversion and attraction to harmful plant secondary compounds jointly shape the foraging ecology of a specialist herbivore.

Most herbivorous insect species are restricted to a narrow taxonomic range of host plant species. Herbivore species that feed on mustard plants and their relatives in the Brassicales have evolved highly efficient detoxification mechanisms that actually prevent toxic mustard oils from forming in the bodies of the animals. However, these mechanisms likely were not present during the initial stages of specialization on mustard plants ~100 million years ago. The herbivorous fly Scaptomyza nigrita (Drosophilidae) is a specialist on a single mustard species, bittercress (Cardamine cordifolia; Brassicaceae) and is in a fly lineage that evolved to feed on mustards only in the past 10–20 million years. In contrast to many mustard specialists, S. nigrita does not prevent formation of toxic breakdown products (mustard oils) arising from glucosinolates (GLS), the primary defensive compounds in mustard plants. Therefore, it is an appealing model for dissecting the early stages of host specialization. Because mustard oils actually form in the bodies of S. nigrita, we hypothesized that in lieu of a specialized detoxification mechanism, S. nigrita may mitigate exposure to high GLS levels within plant tissues using behavioral avoidance. Here, we report that jasmonic acid (JA) treatment increased GLS biosynthesis in bittercress, repelled adult female flies, and reduced larval growth. S. nigrita larval damage also induced foliar GLS, especially in apical leaves, which correspondingly displayed the least S. nigrita damage in controlled feeding trials and field surveys. Paradoxically, flies preferred to feed and oviposit on GLS‐producing Arabidopsis thaliana despite larvae performing worse in these plants versus non‐GLS‐producing mutants. GLS may be feeding cues for S. nigrita despite their deterrent and defensive properties, which underscores the diverse relationship a mustard specialist has with its host when lacking a specialized means of mustard oil detoxification.

Effect of cooking on the contents of glucosinolates and their degradation products in selected Brassica vegetables

Changes in the levels of glucosinolates and their degradation products in selected Brassica vegetables due to the cooking process were investigated. The purple cauliflower was found to be the best source of aliphatic and indole glucosinolates, and it was also abundant in compounds such as sinigrin, glucoraphanin and glucobrassicin. As a result of cooking rutabaga, green cauliflower and purple cauliflower, a significant decrease was noted in total glucosinolates (6.6, 68.9 and 69.2%, respectively) compared to raw vegetables. The hydrothermal processing applied led to a decline in the sum of indoles and isothiocyanates of 48.5 and 11.0%, respectively, in green cauliflower; and of 75.8 and 42.4%, respectively, in purple cauliflower; whereas, in rutabaga it led to an increase of 142.9 and 329.4%, respectively, compared with raw vegetables.

Evaluating strategies to improve glucosinolate concentration and root yield of field-grown horseradish in a Mediterranean environment: preliminary results

Horseradish is grown for its enlarged taproot that is widely used as a dish condiment and as a source of horseradish peroxidase. Nowadays, the species is gaining great interest due to the richness in bioactive compounds that besides providing a high nutritional value are tested for innovative applications in different fields. Nevertheless, the effect of crop management on root yield and glucosinolates (GLS) biosynthesis is poorly documented. Aim of this study was to evaluate the root yield and GLS concentration of two field-grown horseradish accessions (Cor and Mon) grown with nitrogen (N) alone and both N and sulphur (S) (-N-S, +N-S and +N+S treatments) and harvested at different times [late autumn (LA), 2011 and 2012, early spring (ES), 2012]. Yield increased throughout the harvests up to 48% on average of the fertilised treatments and 25% in the unfertilised control. Conversely, root GLS concentration significantly declined in the unfertilised control throughout the harvests [from 7.6 in LA_2011 to 1.43 μmol/g dry matter (DM) in LA_2012] while it highly increased in plants grown with N alone and with both N and S by 46 and 98%, respectively, from LA_2011 to ES_2012 (up to 11.9 and 21.1 μmol/g DM, respectively); then it drastically decreased by 80% on average, in the next harvest. Among individual GLS, the concentration of sinigrin and nasturtin similarly varied as effect of the analysed factors, showing the highest values in Cor accession. The data show that although the level of GLS is highly dependent on genotype, fertilisation and harvesting date may play a primary role in determining the yield and GLS concentration in horseradish root.

The potential of resynthesized lines to provide resistance traits against rape stem weevil in oilseed rape

The rape stem weevil, Ceutorhynchus napi Gyll., is a serious pest of winter oilseed rape (Brassica napus L.) crops in Europe that causes stem distortion, severe disruption of stem growth, and significant yield loss. No resistance has been identified in current B. napus breeding material. Resynthesized lines of oilseed rape can be used to introduce genetic material from the parent species Brassica oleracea L. and B. rapa L. The susceptibility to C. napi of five resynthesized lines and three cultivars of oilseed rape was compared in a multi-choice field plot experiment. Morphological stem traits and stem levels of glucosinolates, carbon, and nitrogen were assessed as potential mediators of resistance. Eggs and larvae of C. napi in stems were counted weekly from the beginning of oviposition to larval maturation and stem pith degeneration in response to oviposition was assessed. Egg counts per stem were negatively dependent on stem length and positively dependent on the levels of five glucosinolates, glucobrassicanapin, glucoalyssin, glucobrassicin, neoglucobrassicin, and gluconasturtiin. The resynthesized line S30 was significantly more resistant to C. napi than the commercial cultivar Sollux, having fewer eggs and larvae. This resistance appeared to be largely antixenotic, due to the combination of a long stem and a paucity of the five key glucosinolates. We propose that resynthesized lines such as S30 should be used to introduce genes determining traits such as long stem length and glucosinolate profile into breeding programs to enhance resistance against C. napi in oilseed rape.

Effects of pretreatment and modified atmosphere packaging on glucosinolate levels in coleslaw mix

The aim of the study was to determine the effect of soaking in an ascorbic acid (5 g/L) and citric acid (5 g/L) solution and modified atmosphere packaging on glucosinolate (GLS) levels in a coleslaw mix stored for 12 days at 4 °C. Samples were packaged under modified atmosphere consisting of 5/10/85, 20/25/55, 50/30/20, 70/30/0% of O2/CO2/N2, as well as air. The in-pack gas levels, the glucosinolate contents (GLS) and the in vitro cytotoxicity of the glucosinolate extract toward human breast cancer cells (MCF-7) were determined. The pre-treatment caused a significant decrease in the contents of aliphatic glucosinolates. During storage, following an initial increase, GLS decreased. After the storage period, the level of aliphatic glucosinolates in the coleslaw mix was 17%–34% lower than in the salad prior to pretreatment, though indole glucosinolates were 21%–152% higher. The 5/10/85% of O2/CO2/N2 atmosphere in packaging of the coleslaw mix resulted in the highest of GLS levels.

Optimizing elicitation and seed priming to enrich broccoli and radish sprouts in glucosinolates

Elicitation is a cheaper and socially acceptable tool for improving plant food functionality. Our objective was to optimize the treatment doses of the elicitors: methyl jasmonate (MeJA), jasmonic acid (JA) and DL-methionine (MET), in order to find a successful and feasible treatment to produce broccoli and radish sprouts with enhanced levels of health-promoting glucosinolates. Also a priming of seeds as a novel strategy to trigger the glucosinolates content was carried out with water (control), MeJA (250μM), JA (250μM) and MET (10mM) before the elicitor exogenous treatment. The results showed that almost all treatments could enhance effectively the total glucosinolates content in the sprouts, achieving the most significant increases from 34% to 100% of increase in broccoli and from 45% to 118% of increase in radish sprouts after MeJA priming and treatments. Consequently, our work demonstrates the feasibility of using elicitors, such as plant stress hormones, by priming and exogenously, as a way of increase the phytochemical profile of these sprouts to enhance their consumption in the diet.

The rolB gene activates secondary metabolism in Arabidopsis calli via selective activation of genes encoding MYB and bHLH transcription factors

It is known that the rolB gene of Agrobacterium rhizogenes increases the production of secondary metabolites in transformed plant cells, but its mechanism of action remains unclear. In this report, we demonstrate that rolB expression in Arabidopsis thaliana calli led to the activation of most genes encoding secondary metabolism-specific MYB and bHLH transcription factors (TFs), such as MYB11, MYB12, MYB28, MYB76, MYB34, MYB51, MYB122, TT2 and TT8. Accordingly, a higher transcript abundance of main biosynthetic genes related to these factors was detected. The rolB-transformed calli produced 3-fold higher levels of indolic glucosinolates (GSs) compared with normal calli but did not produce secondary metabolites from other groups. Enhanced accumulation of indolic GSs was caused by activation of MYB34, MYB51 and MYB122, and the absence of aliphatic GSs in transformed calli was caused by the inability of rolB to induce MYB29. The inability of rolB-calli to produce flavonoids was caused by the lack of MYB111 expression, induced by the rolB-mediated conversion of MYB expression from cotyledon-specific to root-specific patterns. The high specificity of rolB on secondary metabolism-specific TFs was demonstrated for the first time.

Optimization of Engineered Production of the Glucoraphanin Precursor Dihomomethionine in Nicotiana benthamiana

Glucosinolates are natural products characteristic of the Brassicales order, which include vegetables such as cabbages and the model plant Arabidopsis thaliana. Glucoraphanin is the major glucosinolate in broccoli and associated with the health-promoting effects of broccoli consumption. Toward our goal of creating a rich source of glucoraphanin for dietary supplements, we have previously reported the feasibility of engineering glucoraphanin in Nicotiana benthamiana through transient expression of glucoraphanin biosynthetic genes from A. thaliana (Mikkelsen et al., 2010). As side-products, we obtained fivefold to eightfold higher levels of chain-elongated leucine-derived glucosinolates, not found in the native plant. Here, we investigated two different strategies to improve engineering of the methionine chain elongation part of the glucoraphanin pathway in N. benthamiana: (1) coexpression of the large subunit (LSU1) of the heterodimeric isopropylmalate isomerase and (2) coexpression of BAT5 transporter for efficient transfer of intermediates across the chloroplast membrane. We succeeded in raising dihomomethionine (DHM) levels to a maximum of 432 nmol g−1 fresh weight that is equivalent to a ninefold increase compared to the highest production of this intermediate, as previously reported (Mikkelsen et al., 2010). The increased DHM production without increasing leucine-derived side-product levels provides new metabolic engineering strategies for improved glucoraphanin production in a heterologous host.

Aromatic Glucosinolate Biosynthesis Pathway in Barbarea vulgaris and its Response to Plutella xylostella Infestation.

The inducibility of the glucosinolate resistance mechanism is an energy-saving strategy for plants, but whether induction would still be triggered by glucosinolate-tolerant Plutella xylostella (diamondback moth, DBM) after a plant had evolved a new resistance mechanism (e.g., saponins in Barbara vulgaris) was unknown. In B. vulgaris, aromatic glucosinolates derived from homo-phenylalanine are the dominant glucosinolates, but their biosynthesis pathway was unclear. In this study, we used G-type (pest-resistant) and P-type (pest-susceptible) B. vulgaris to compare glucosinolate levels and the expression profiles of their biosynthesis genes before and after infestation by DBM larvae. Two different stereoisomers of hydroxylated aromatic glucosinolates are dominant in G- and P-type B. vulgaris, respectively, and are induced by DBM. The transcripts of genes in the glucosinolate biosynthesis pathway and their corresponding transcription factors were identified from an Illumina dataset of G- and P-type B. vulgaris. Many genes involved or potentially involved in glucosinolate biosynthesis were induced in both plant types. The expression patterns of six DBM induced genes were validated by quantitative PCR (qPCR), while six long-fragment genes were validated by molecular cloning. The core structure biosynthetic genes showed high sequence similarities between the two genotypes. In contrast, the sequence identity of two apparent side chain modification genes, the SHO gene in the G-type and the RHO in P-type plants, showed only 77.50% identity in coding DNA sequences and 65.48% identity in deduced amino acid sequences. The homology to GS-OH in Arabidopsis, DBM induction of the transcript and a series of qPCR and glucosinolate analyses of G-type, P-type and F1 plants indicated that these genes control the production of S and R isomers of 2-hydroxy-2-phenylethyl glucosinolate. These glucosinolates were significantly induced by P. xylostella larvae in both the susceptiple P-type and the resistant G-type, even though saponins are the main DBM-resistance causing metabolites in G-type plants. Indol-3-ylmethylglucosinolate was induced in the G-type only. These data will aid our understanding of the biosynthesis and induction of aromatic glucosinolates at the molecular level and also increase our knowledge of the complex mechanisms underpinning defense induction in plants.

Conversion of Canola Meal into a High‐Protein Feed Additive via Solid‐State Fungal Incubation Process

AbstractThe study goal was to determine the optimal fungal culture to reduce glucosinolates (GLS), fiber, and residual sugars while increasing the protein content and nutritional value of canola meal. Solid‐state incubation conditions were used to enhance filamentous growth of the fungi. Flask trials were performed using 50 % moisture content hexane‐extracted (HE) or cold‐pressed (CP) canola meal with incubation for 168 h at 30 °C. Incubation on HE canola meal Trichoderma reesei (NRRL‐3653) achieved the greatest increase in protein content (23 %), while having the lowest residual levels of sugar (8 % w/w) and GLS (0.4 μM/g). Incubation on CP canola meal Trichoderma reesei (NRRL‐3653), A. pullulans (NRRL‐58522), and A. pullulans (NRRL‐Y‐2311‐1) resulted in the greatest improvement in protein content (22.9, 16.9 and 15.4 %, respectively), while reducing total GLS content from 60.6 to 1.0, 3.2 and 10.7 μM/g, respectively. HE and CP canola meal GLS levels were reduced to 65.5 and 50.7 % by thermal treatments while solid‐state microbial conversion further reduced GLS up to 99 and 98 %, respectively. Fiber levels increased due to the concentration effect of removing oligosaccharides and GLS.

Glucosinolates in broccoli (Brassica oleracea L. var. italica) as affected by postharvest temperature and radiation treatments

The purpose of the present study was to examine how glucosinolate (GLS) levels in broccoli flower buds are affected by storage time, temperature and radiation treatments in an experiment with multi-level design simulating mapped commercial storage conditions from harvest until consumer purchase. The GLS content in broccoli flower buds was examined during pre-storage and storage of broccoli heads, representing refrigerated transport with wholesale distribution and retail, respectively. The GLS analysis was conducted also for floret stalks of chosen broccoli. Broccoli heads were pre-stored for four or seven days at 0 or 4°C in the dark and then stored for three days at 10 or 18°C. During storage, the broccoli heads were exposed for 12h per day to three different levels of visible light (13, 19 or 25μmolm−2s−1) or a combination of visible light (19μmolm−2s−1) and UV-B irradiation (20kJm−2d−1), or they were stored in the dark. The GLS contents were not changed in broccoli flower buds during pre-storage at low temperatures (0°C or 4°C) for four or seven days. However, general linear model analysis revealed that pre-storage period significantly influenced total GLS, total indolyl and total aliphatic GLS, and all individual GLS levels, except for 4-methoxyglucobrassicin (4-Me-GB) in broccoli flower buds after storage at higher temperatures (10°C or 18°C). Higher levels of these compounds were found in broccoli pre-stored for seven days than in those pre-stored for four days. Storage temperature affected GLS levels in broccoli flower buds significantly. 4-Hydroxyglucobrassicin (4-OH-GB) content was increased after storage at 18°C, while the levels of all other individual GLS, total GLS, as well as total aliphatic and indolyl GLS were higher in flower buds of broccoli after storage at 10°C than at 18°C. The effect of storage temperature on aliphatic GLS in broccoli flower buds depended on pre-storage temperature and it was negligible for broccoli heads pre-stored at 4°C but significant for those pre-stored at 0°C. Radiation treatments applied during storage did not influence total and individual GLS levels in broccoli flower buds. However, the accumulation of aliphatic GLS in broccoli pre-stored for seven days at 0°C and subsequently stored for three days at 10°C under visible light of 25μmolm−2s−1 appeared both in flower buds and floret stalks. Significant increases in indolyl 4-OH-GB and 4-Me-GB contents were observed only in flower buds or floret stalks after storage at 18°C upon exposure to visible light of 25μmolm−2s−1.

Modification of oil and glucosinolate content in canola seeds with altered expression of Brassica napus LEAFY COTYLEDON1

Over the last few decades, research focusing on canola (Brassica napus L.) seed oil content and composition has expanded. Oil production and accumulation are influenced by genes participating in embryo and seed development. The Arabidopsis LEAFY COTYLEDON1 (LEC1) is a well characterized regulator of embryo development that also enhances the expression of genes involved in fatty acid (FA) synthesis. B. napus lines over-expressing or down-regulating BnLEC1 were successfully generated by Agrobacterium-mediated transformation. The constitutive expression of BnLEC1 in B. napus var. Polo, increased seed oil content by 7–16%, while the down-regulation of BnLEC1 in B. napus var. Topas reduced oil content by 9–12%. Experimental manipulation of BnLEC1 caused transcriptional changes in enzymes participating in sucrose metabolism, glycolysis, and FA biosynthesis, suggesting an enhanced carbon flux towards FA biosynthesis in tissues over-expressing BnLEC1. The increase in oil content induced by BnLEC1 was not accompanied by alterations in FA composition, oil nutritional value or glucosinolate (GLS) levels. Suppression of BnLEC1 reduced seed oil accumulation and elevated the level of GLS possibly through the transcriptional regulation of BnST5a (Sulphotransferase5a), the last GLS biosynthetic enzyme. Collectively, these findings demonstrate that experimental alterations of BnLEC1 expression can be used to influence oil production and quality in B. napus.

Glucosinolate biosynthesis as influenced by growth media and auxin in hairy root cultures of Kale (Brassica oleracea var. acephala)

This study aimed to investigate the effects of various growth media and three types of auxins on glucosinolate biosynthesis in hairy root cultures of kale. Four different glucosinolates (4-hydroxyglucobrassicin, glucobrassicin, 4-methoxyglucobrassicin, and neoglucobrassicin) were used in this study. The accumulation of glucosinolates was influenced by both media and auxin treatments. Of the media treatments, full-strength Gamborg’s B5 medium (B5) supported the highest accumulation of total glucosinolates, followed by full-strength Murashige–Skoog medium (MS), whereas the lowest glucosinolates accumulation was in the half-strength MS medium treatment. The accumulation of glucobrassicin was very high, followed by 4-methoxyglucobrassicin, irrespective of the growth medium used. The highest content of glucobrassicin was measured in cultures in B5 medium, while MS medium resulted in the highest accumulation of 4-methoxyglucobrassicin. Half-strength B5 medium resulted in the highest content of neoglucobrassicin, and Schenk and Hildebrandt medium (SH) supported the highest content of 4-hydroxyglucobrassicin. The total and individual levels of glucosinolates in hairy root cultures of kale were all influenced by exposure to the nine auxin treatments, with the exception glucobrassicin. In general, levels of glucosinolate decreased with increasing concentrations of auxins. Treatment with the auxin indole-3-butyric acid (IBA) 0.1 resulted in the highest total concentration of glucosinolates, measuring 1.83 times higher than that of hairy root cultures treated with naphthalene acetic acid (NAA) 1.0, which resulted in the lowest glucosinolate concentrations. Of the four glucosinolates, glucobrassicin and 4-methoxyglucobrassicin contents were considerably higher. The auxin IBA 0.1 promoted the highest 4-methoxyglucobrassicin accumulation in the hairy root cultures of kale. The auxin treatment indole-3-acetic acid (IAA) 0.1 resulted in the highest amount of 4-hydroxyglucobrassicin and neoglucobrassicin. Hairy root cultures could be a valuable alternative approach for the production of glucosinolate compounds from kale.