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Glucosinolates (GSLs) are specialized metabolites in plants of the order Brassicales. GSL transporters (GTRs) are essential for the redistribution of GSLs and also play a role in controlling the GSL content of seeds. However, specific inhibitors of these transporters have not been reported. In the current study, we described the design and synthesis of 2,3,4,6- t etrachloro-5- c yano p henyl G SL (TCPG), an artificial GSL bearing a chlorothalonil moiety as a potent inhibitor of GTRs, and evaluated its inhibitory effect on the substrate uptake mediated through GTR1 and GTR2. Molecular docking showed that the position of the β-D-glucose group of TCPG was significantly different from that of the natural substrate in GTRs and the chlorothalonil moiety forms halogen bonds with GTRs. Functional assays and kinetic analysis of the transport activity revealed that TCPG could significantly inhibit the transport activity of GTR1 and GTR2 (IC 50 values (mean ± SD) being 79 ± 16 μM and 192 ± 14 μM, respectively). Similarly, TCPG could inhibit the uptake and phloem transport of exogenous sinigrin by Arabidopsis thaliana (L.) Heynh leaf tissues, while not affecting that of esculin (a fluorescent surrogate for sucrose). TCPG could also reduce the content of endogenous GSLs in phloem exudates. Together, TCPG was discovered as an undescribed inhibitor of the uptake and phloem transport of GSLs, which brings novel insights into the ligand recognition of GTRs and provides a new strategy to control the GSL level. Further tests on the ecotoxicological and environmental safety of TCPG are needed before using it as an agricultural or horticultural chemical in the future. An artificial glucosinolate bearing a chlorothalonil moiety was synthesized, and its inhibitory effect on the glucosinolate uptake mediated through GTR1 and GTR2 transporters was evaluated. [Display omitted] • GTR1 and GTR2 are key targets for glucosinolate content modulation. • An artificial GSL bearing a chlorothalonil as an inhibitor of GTRs was synthesized. • The inhibitor was named 2,3,4,6-tetrachloro-5-cyanophenyl GSL (TCPG). • The R moiety of TCPG could form halogen bonds with GTRs. • TCPG could inhibit the GTR-mediated influx of GSLs. [ABSTRACT FROM AUTHOR]

The adverse effect of glucosinolates on diverse phytophagous insects is well documented, but its impact on insect physiology has remained enigmatic. Here we report insights into detrimental effects of plant glucosinolate molecule, sinigrin, on Helicoverpa armigera growth and development. In - silico screening of multiple glucosinolates predicted sinigrin as one of the potential inhibitor of H. armigera cathepsin B and L. Insects fed on sinigrin containing diet showed significantly reduced growth (20–30%), delayed pupation (10–15%), decreased fecundity (50–80%) and developmental abnormalities. Further, sinigrin showed 50–60% inhibition of ex - vivo cathepsin like activity which might be a reason for growth and development related abnormalities. In-vitro and mass spectrometry studies highlighted the cytotoxicity caused due to the hydrolysis of sinigrin, into toxic isothiocyanates, in presence of H. armigera whole body extract. In conclusion, insect cathepsin inhibition and isothiocyanate mediated cytotoxicity lead to the dual adverse effect of sinigrin on H. armigera . [ABSTRACT FROM AUTHOR]

The brassicaceous herb, Isatis tinctoria, is an ancient medicinal plant whose rosette leaf extracts have anti-inflammatory and anti-allergic activity. Brassicaceae are known to accumulate a variety of phenylpropanoids in their rosette leaves acting as antioxidants and a UV-B shield, and these compounds often have pharmacological potential. Nevertheless, knowledge about the phenylpropanoid content of I. tinctoria leaves remains limited to the characterization of a number of flavonoids. In this research, we profiled the methanol extracts of I. tinctoria fresh leaf extracts by liquid chromatography – mass spectrometry (LC-MS) and focused on the phenylpropanoid derivatives. We report the structural characterization of 99 compounds including 18 flavonoids, 21 mono- or oligolignols, 2 benzenoids, and a wide spectrum of 58 hydroxycinnamic acid esters. Besides the sinapate esters of malate, glucose and gentiobiose, which are typical of brassicaceous plants, these conjugates comprised a large variety of glucaric acid esters that have not previously been reported in plants. Feeding with 13 C 6 -glucaric acid showed that glucaric acid is an acyl acceptor of an as yet unknown acyltransferase activity in I. tinctoria rosette leaves. The large amount of hydroxycinnamic acid derivatives changes radically our view of the woad metabolite profile and potentially contributes to the pharmacological activity of I. tinctoria leaf extracts. [ABSTRACT FROM AUTHOR]

Plants that are able to hyperaccumulate heavy metals show increased concentrations of these metals in their leaf tissue. However, little is known about the concentrations of heavy metals and of organic defence metabolites in the phloem sap of these plants in response to either heavy metal-amendment of the soil or biotic challenges such as aphid-infestation. In this study, we investigated the effects of heavy metal-exposure and of aphid-infestation on phloem exudate composition of the metal hyperaccumulator species Arabidopsis halleri L. O'Kane & Al-Shehbaz (Brassicaceae). The concentrations of elements and of organic defence compounds, namely glucosinolates, were measured in phloem exudates of young and old (mature) leaves of plants challenged either by amendment of the soil with cadmium and zinc and/or by an infestation with the generalist aphid Myzus persicae . Metal-amendment of the soil led to increased concentrations of Cd and Zn, but also of two other elements and one indole glucosinolate, in phloem exudates. This enhanced defence in the phloem sap of heavy metal-hyperaccumulating plants can thus potentially act as effective protection against aphids, as predicted by the elemental defence hypothesis. Aphid-infestation also caused enhanced Cd and Zn concentrations in phloem exudates. This result provides first evidence that metal-hyperaccumulating plants can increase heavy metal concentrations tissue-specifically in response to an attack by phloem-sucking herbivores. Overall, the concentrations of most elements, including the heavy metals, and glucosinolates were higher in phloem exudates of young leaves than in those of old leaves. This defence distribution highlights that the optimal defence theory, which predicts more valuable tissue to be better defended, is applicable for both inorganic and organic defences. [ABSTRACT FROM AUTHOR]

As a basis for future investigations of evolutionary trajectories and biosynthetic mechanisms underlying variations in glucosinolate structures, we screened members of the crucifer tribe Cardamineae by HPLC-MS/MS, isolated and identified glucosinolates by NMR, searched the literature for previous data for the tribe, and collected HPLC-MS/MS data for nearly all glucosinolates known from the tribe as well as some related structures (70 in total). This is a considerable proportion of the approximately 142 currently documented natural glucosinolates. Calibration with authentic references allowed distinction (or elucidation) of isomers in many cases, such as distinction of β-hydroxyls, methylthios, methylsulfinyls and methylsulfonyls. A mechanism for fragmentation of secondary β-hydroxyls in MS was elucidated, and two novel glucosinolates were discovered: 2-hydroxy-3-methylpentylglucosinolate in roots of Cardamine pratensis and 2-hydroxy-8-(methylsulfinyl)octylglucosinolate in seeds of Rorippa amphibia . A large number of glucosinolates (ca. 54 with high structural certainty and a further 28 or more suggested from tandem MS), representing a wide structural variation, is documented from the tribe. This included glucosinolates apparently derived from Met, Phe, Trp, Val/Leu, Ile and higher homologues. Normal side chain elongation and side chain decoration by oxidation or methylation was observed, as well as rare abnormal side chain decoration (hydroxylation of aliphatics at the δ rather than β-position). Some species had diverse profiles, e.g. R. amphibia and C. pratensis (19 and 16 individual glucosinolates, respectively), comparable to total diversity in literature reports of Armoracia rusticana (17?), Barbarea vulgaris (20–24), and Rorippa indica (>20?). The ancestor or the tribe would appear to have used Trp, Met, and homoPhe as glucosinolate precursor amino acids, and to exhibit oxidation of thio to sulfinyl, formation of alkenyls, β-hydroxylation of aliphatic chains and hydroxylation and methylation of indole glucosinolates. Two hotspots of apparent biochemical innovation and loss were identified: C. pratensis and the genus Barbarea. Diversity in other species mainly included structures also known from other crucifers. In addition to a role of gene duplication, two contrasting genetic/biochemical mechanisms for evolution of such combined diversity and redundancy are discussed: (i) involvement of widespread genes with expression varying during evolution, and (ii) mutational changes in substrate specificities of CYP79F and GS-OH enzymes. [ABSTRACT FROM AUTHOR]

Plants are unrivaled in the natural world in both the number and complexity of secondary metabolites they produce, and the ubiquitous phenylpropanoids and the lineage-specific glucosinolates represent two such large and chemically diverse groups. Advances in genome-enabled biochemistry and metabolomic technologies have greatly increased the understanding of their metabolic networks in diverse plant species. There also has been some progress in elucidating the gene regulatory networks that are key to their synthesis, accumulation and function. This review highlights what is currently known about the gene regulatory networks and the stable sub-networks of transcription factors at their cores that regulate the production of these plant secondary metabolites and the differentiation of specialized cell types that are equally important to their defensive function. Remarkably, some of these core components are evolutionarily conserved between secondary metabolism and specialized cell development and across distantly related plant species. These findings suggest that the more ancient gene regulatory networks for the differentiation of fundamental cell types may have been recruited and remodeled for the generation of the vast majority of plant secondary metabolites and their specialized tissues. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The glucosinolate pathway, which is present in the order Brassicales, is one of the most researched defensive natural product biosynthesis pathways. Its core molecules, the glucosinolates are broken down upon pathogen challenge or tissue damage to yield an array of natural products that may help plants defend against the stressor. Though the most widely known glucosinolate decomposition products are the antimicrobial isothiocyanates, there is a wide range of other volatile and non-volatile natural products that arise from this biosynthetic pathway. This review summarizes our current knowledge on the interaction of these much less examined, non-isothiocyanate products with fungi. It deals with compounds including (1) glucosinolates and their biosynthesis precursors; (2) glucosinolate-derived nitriles (e.g. derivatives of 1 H -indole-3-acetonitrile), thiocyanates, epithionitriles and oxazolidine-2-thiones; (3) putative isothiocyanate downstream products such as raphanusamic acid, 1 H -indole-3-methanol (= indole-3-carbinol) and its oligomers, 1 H -indol-3-ylmethanamine and ascorbigen; (4) 1 H -indole-3-acetonitrile downstream products such as 1 H -indole-3-carbaldehyde (indole-3-carboxaldehyde), 1 H -indole-3-carboxylic acid and their derivatives; and (5) indole phytoalexins including brassinin, cyclobrassinin and brassilexin. Herein, a literature review on the following aspects is provided: their direct antifungal activity and the proposed mechanisms of antifungal action, increased biosynthesis after fungal challenge, as well as data on their biotransformation/detoxification by fungi, including but not limited to fungal myrosinase activity. [Display omitted] • Glucosinolates are precursors of a large variety of downstream products. • Glucosinolate downstream products are key in fungal challenge. • Glucosinolate downstream products show antifungal activity with various potency. • Several fungi can use glucosinolates or nitriles derived from them as nutrients. • Fungi produce specific enzymes to metabolize glucosinolates or downstream products. [ABSTRACT FROM AUTHOR]

Isothiocyanates (ITCs), released from Brassicales plants after hydrolysis of glucosinolates, are known for their negative effects on herbivores but mechanisms have been elusive. The ITCs are initially present in dissolved form at the site of herbivore feeding, but volatile ITCs may subsequently enter the gas phase and all ITCs may react with matrix components. Deterrence to herbivores resulting from topically applied volatile ITCs in artificial feeding assays may hence lead to ambiguous conclusions. In the present study, the non-volatile ITC moringin (4-(α- l -rhamnopyranosyloxy)benzyl ITC) and its glucosinolate precursor glucomoringin were examined for effects on behaviour and taste physiology of specialist insect herbivores of Brassicales. In feeding bioassays, glucomoringin was not deterrent to larvae of Pieris napi (Lepidoptera: Pieridae) and Athalia rosae (Hymenoptera: Tenthredinidae), which are adapted to glucosinolates. Glucomoringin stimulated feeding of larvae of the related Pieris brassicae (Lepidoptera: Pieridae) and also elicited electrophysiological activity from a glucosinolate-sensitive gustatory neuron in the lateral maxillary taste sensilla. In contrast, the ITC moringin was deterrent to P. napi and P. brassicae at high levels and to A. rosae at both high and low levels when topically applied to cabbage leaf discs (either 12, 120 or 1200 nmol moringin per leaf disc of 1 cm diameter). Survival of A. rosae was also significantly reduced when larvae were kept on leaves treated with moringin for several days. Furthermore, moringin elicited electrophysiological activity in a deterrent-sensitive neuron in the medial maxillary taste sensillum of P. brassicae , providing a sensory mechanism for the deterrence and the first known ITC taste response of an insect. In simulated feeding assays, recovery of moringin was high, in accordance with its non-volatile nature. Our results demonstrate taste-mediated deterrence of a non-volatile, natural ITC to glucosinolate-adapted insects. [ABSTRACT FROM AUTHOR]

Glucosinolates are nitrogen and sulfur containing secondary metabolites found mainly in the Brassicaceae. They function as plant defense compounds against a broad spectrum of pathogens and pests. Since these molecules form part of the plant defense mechanism, glucosinolate biosynthesis may be modulated by environmental signals leading to activation of a biological stress response. In the current study, we have mimicked such conditions by exogenously applying biotic elicitors such as methyl jasmonate, salicylic acid, glucose and mechanical injury in Brassica juncea seedling over a time course experiment. We found that total glucosinolates over-accumulated under these stress conditions with maximum accumulation observed 24 h post treatment. Indole glucosinolates like 1-methoxy-indol-3-ylmethyl and its precursor indol-3-methyl glucosinolates showed a more significant induction compared to aliphatic glucosinolates thereby suggesting a prominent role of indole glucosinolates during plant defense response in B. juncea seedlings. In contrast, the higher amounts of aliphatic glucosinolates were less regulated by the tested biotic elicitors in B. juncea . Expression profiling of multiple homologs of key transcriptional regulators of glucosinolate biosynthesis further showed that a complex interplay of these regulators exists in polyploid B. juncea where they exert co-ordinated and overlapping effects toward altering glucosinolate accumulation. This study has a significant role toward understanding and augmenting plant defense mechanisms in B. juncea , a globally important oilseed crop of genus Brassica . [ABSTRACT FROM AUTHOR]

Maca, Lepidium meyenii Walpers (Brassicaceae), is an annual herbaceous plant native to the high plateaus of the Peruvian central Andes. Its underground storage hypocotyls have been a traditional medicinal agent and dietary staple since pre-Columbian times. Reported properties include energizing and fertility-enhancing effects. Published reports have focused on the benzylalkamides (macamides) present in dry hypocotyls as one of the main bioactive components. Macamides are secondary amides formed by benzylamine and a fatty acid moiety, with varying hydrocarbon chain lengths and degree of unsaturation. Although it has been assumed that they are usually present in fresh undamaged tissues, analyses show them to be essentially absent from them. However, hypocotyls dried by traditional Andean postharvest practices or industrial oven drying contain up to 800 μg g −1 dry wt (2.3 μmol g −1 dry wt) of macamides. In this study, the generation of macamides and their putative precursors were studied during nine-week traditional drying trials at 4200 m altitude and in ovens under laboratory conditions. Freeze–thaw cycles in the open field during drying result in tissue maceration and release of free fatty acids from storage and membrane lipids up to levels of 1200 μg g −1 dry wt (4.3 μmol g −1 dry wt). Endogenous metabolism of the isothiocyanates generated from glucosinolate hydrolysis during drying results in maximal benzylamine values of 4300 μg g −1 dry wt (40.2 μmol g −1 dry wt). Pearson correlation coefficients of the accumulation profiles of benzylamine and free fatty acid to that of macamides showed good values of 0.898 and 0.934, respectively, suggesting that both provide sufficient substrate for amide synthesis during the drying process. [ABSTRACT FROM AUTHOR]

Two isomeric phenolic glucosinolates, m - and p- hydroxyl derivatives of epiglucobarbarin [( R )-2-hydroxy-2-phenylethylglucosinolate], co-occur in an eastern chemotype (P-type) of the crucifer Barbarea vulgaris along with epiglucobarbarin itself. Levels of the phenolic derivatives in B. vulgaris were low in summer but higher during fall and winter, allowing isolation of all three glucosinolates. Hydrolysis in vitro , catalyzed by Sinapis alba myrosinase at near neutral pH, resulted in expectable oxazolidine-2-thione type hydrolysis products of epiglucobarbarin and its m -hydroxyl derivative. In contrast, a thiazolidine-2-one type product was formed in vitro from p -hydroxy epiglucobarbarin and characterized by UV, IR, MS/MS and 2D NMR. Maceration of leaf material resulted in disappearance of the glucosinolates and formation of the same oxazolidine-2-thione and thiazolidine-2-one products as found in vitro . The detected amounts were comparable to initial amounts of precursor glucosinolates. The corresponding oxazolidine-2-thione type product was also detected quantitatively from glucobarbarin in foliage of a western genotype (G-type). We suggest that p -hydroxy epiglucobarbarin is initially converted into the conventional oxazolidine-2-thione, which would further rearrange to a thiazolidine-2-one due to the activating effect of the p -hydroxyl group. We conclude that a subtle difference between isomeric phenolic glucosinolates results in significantly different natural hydrolysis products. [ABSTRACT FROM AUTHOR]

Two distinct glucosinolate (GSL) chemotypes (P and G-types) of Barbarea vulgaris (Brassicaceae) were known from southern Scandinavia, but whether the types were consistent in a wider geographic area was not known. Populations (26) from Eastern and Central Europe were analyzed for GSLs in order to investigate whether the two types were consistent in this area. Most (21) could be attributed to one of the previously described GSL profile types, the P-type (13 populations) and the G-type (8 populations), based on differences in the stereochemistry of 2-hydroxylation, presence or absence of phenolic glucobarbarin derivatives, and qualitative differences in indole GSL decoration (tested for a subset of 8 + 6 populations only). The distinction agreed with previous molecular genetic analysis of the same individuals. Geographically, the P-type typically occurred in Eastern Europe while the G-type mainly occurred in Central Europe. Of the remaining five populations, minor deviations were observed in some individuals from two populations genetically assigned to the G-type, and a hybrid population from Finland contained an additional dihydroxyphenethyl GSL isomer attributed to a combinatorial effect of P-type and G-type genes. Major exceptions to the typical GSL profiles were observed in two populations: (1) A G-type population from Slovenia deviated by a high frequency of a known variant in glucobarbarin biosynthesis (‘NAS form’) co-occurring with usual G-type individuals. (2) A population from Caucasus exhibited a highly deviating GSL profile dominated by p -hydroxyphenethyl GSL that was insignificant in other accessions, as well as two GSLs investigated by NMR, m -hydroxyphenethylGSL and a partially identified m , p disubstituted hydroxy-methoxy derivative of phenethylGSL. Tandem HPLC–MS of seven NMR-identified desulfoGSLs was carried out and interpreted for increased certainty in peak identification and as a tool for partial structure elucidation. The distinct, geographically separated chemotypes and rare variants are discussed in relation to future taxonomic revision and the genetics and ecology of GSLs in B. vulgaris. [ABSTRACT FROM AUTHOR]

The glucosinolates content of brassica plants is a distinctive characteristic, representing a healthy advantage as many of these compounds are associated to antioxidant and anti-carcinogenic properties. Brassica sprouts are still an underutilized source of these bioactive compounds. In this work, four varieties of brassica sprouts (red cabbage, broccoli, Galega kale and Penca cabbage), including two local varieties from the North of Portugal, were grown to evaluate the glucosinolate profile and myrosinase activity during the sprouting. Also the influence of light/darkness exposure during sprouting on the glucosinolate content was assessed. Glucosinolate content and myrosinase activity of the sprouts was evaluated by HPLC methods. All sprouts revealed a higher content of aliphatic glucosinolates than of indole glucosinolates, contrary to the profile described for most of brassica mature plants. Galega kale sprouts had the highest glucosinolate content, mainly sinigrin and glucoiberin, which are recognized for their beneficial health effects. Penca cabbage sprouts were particularly richer in glucoraphanin, who was also one of the major compounds in broccoli sprouts. Red cabbage showed a higher content of progoitrin. Regarding myrosinase activity, Galega kale sprouts showed the highest values, revealing that the use of light/dark cycles and a sprouting phase of 7–9 days could be beneficial to preserve the glucosinolate content of this variety. [ABSTRACT FROM AUTHOR]

Glucosinolates are secondary plant compounds typically found in members of the Brassicaceae and a few other plant families. Usually each plant species contains a specific subset of the ∼130 different glucosinolates identified to date. However, intraspecific variation in glucosinolate profiles is commonly found. Sinalbin (4-hydroxybenzyl glucosinolate) so far has been identified as the main glucosinolate of the heavy metal accumulating plant species Noccaea caerulescens (Brassicaceae). However, a screening of 13 N. caerulescens populations revealed that in 10 populations a structurally related glucosinolate was found as the major component. Based on nuclear magnetic resonance (NMR) and mass spectrometry analyses of the intact glucosinolate as well as of the products formed after enzymatic conversion by sulfatase or myrosinase, this compound was identified as 4-α-rhamnosyloxy benzyl glucosinolate (glucomoringin). So far, glucomoringin had only been reported as the main glucosinolate of Moringa spp. (Moringaceae) which are tropical tree species. There was no apparent relation between the level of soil pollution at the location of origin, and the presence of glucomoringin. The isothiocyanate that is formed after conversion of glucomoringin is a potent antimicrobial and antitumor agent. It has yet to be established whether glucomoringin or its breakdown product have an added benefit to the plant in its natural habitat. [ABSTRACT FROM AUTHOR]

Profile and distribution of glucosinolates (GLS) were detected in plant tissues of horseradish at different developmental stages: beginning of vegetative re-growth, flowering and silique formation. The GLS profile varied widely in the different tissues: we identified 17 GLS in roots and sprouts, one of which was not previously characterized in horseradish, i.e. the 2(S)-hydroxy-2-phenylethyl-GLS (glucobarbarin) and/or 2(R)-hydroxy-2-phenylethyl-GLS (epiglucobarbarin), 11 already found in the roots, including the putative 2-methylsulfonyl-oxo-ethyl-GLS, and 5 previously recognized only in the sprouts. Fifteen of those GLS were also identified in young and cauline leaves, 12 in the mature leaves and 13 in the inflorescences. No difference in GLS profile was observed in plant among the phenological stages. Differences in concentrations of GLS, quantified as desulfated, were found in plant. At the beginning of vegetative re-growth, sprouts while showing the same profile of the roots were much richer in GLS having the highest total GLS concentrations (117.5 and 7.7 μmol g −1 dry weight in sprouts and roots, respectively). During flowering and silique forming stages, the roots still maintained lower amount of total GLS (7.4 μmol g −1 of dry weight, on average) with respect to the epigeous tissues, in which mature and young leaves showed the highest total concentrations (70.5 and 73.8 μmol g −1 of dry weight on average, respectively). Regardless of the phenological stages, the aliphatic GLS were always predominant in all tissues (95%) followed by indolic (2.6%) and benzenic (2.4%) GLS. Sinigrin contributed more than 90% of the total GLS concentration. Aliphatic GLS concentrations were much higher in the epigeous tissues, particularly in the mature and young leaves, while benzenic and indolic GLS concentrations were higher in the roots. Through the phenological stages, GLS concentration increased in young and mature leaves and decreased in cauline leaves and inflorescences, while it remained constant over time in roots. [ABSTRACT FROM AUTHOR]

Plant specialized metabolites are often subject to within-plant transport and have tissue-specific distribution patterns. Among plants in the Brassicaceae, the genus Erysimum is unique in producing not only glucosinolates but also cardenolides. Ten cardenolides were detected with varying abundance in different tissues of Erysimum cheiranthoides L (Brassicaceae; wormseed wallflower). As is predicted by the optimal defense theory, cardenolides were most abundant in young leaves and reproductive tissues. The lowest concentrations were observed in senescing leaves and roots. Crosses between wildtype E. cheiranthoides and a mutant line with an altered cardenolide profile showed that the seed cardenolide phenotype is determined entirely by the maternal genotype. Prior to the development of the first true leaves, seedling cotyledons also had the maternal cardenolide profile. Hypocotyl grafting experiments showed that the root cardenolide profile is determined entirely by the aboveground plant genotype. In further grafting experiments, there was no evidence of cardenolide transport into the leaves, but a mixed cardenolide profile was observed in the stems and inflorescences of plants that had been grafted at vegetative and flowering growth stages, respectively. Together, these results indicate that E. cheiranthoides leaves are a site of cardenolide biosynthesis. Cardiac glycosides in Erysimum cheiranthoides (Brassicaceae L; wormseed wallflower) are transported from leaves to roots and reproductive tissue. [Display omitted] • Cardenolide content of Erysimum cheiranthoides (wormseed wallflower) varies by tissue type. • The aboveground plant genotype determines the root cardenolide phenotype. • Cardenolides are transported from maternal tissue to developing seeds. • Cotyledons have a cardenolide phenotype that is determined by the maternal plant. • Seedling cardenolide biosynthesis is initiated with the emergence of true leaves. [ABSTRACT FROM AUTHOR]

Highlights: [•] Tandem MS with IRMPD FTICR MS was applied for acylated glucosinolates (a-GLSs). [•] Structures of four new trace a-GLSs were elucidated in seed extracts of Barbarea vulgaris. [•] Three previously known a-GLSs were confirmed. [•] Glucobarbarin is now documented to exist as four different acyl derivatives. [•] Quantitative evaluation showed the isoferuloyl conjugate to be predominant. [ABSTRACT FROM AUTHOR]

Highlights: [•] ArMY2 is the first MYR II myrosinase gene described in Armoracia rusticana. [•] ArMY2 encodes a myrosinase and is selectively expressed in young horseradish roots. [•] Gluconasturtiin is the dominant glucosinolate in young horseradish roots. [•] Recombinant ArMy2 produced in Pichia pastoris prefers gluconasturtiin as substrate. [•] A specialized glucosinolate-myrosinase defense system may be active in young roots. [ABSTRACT FROM AUTHOR]

Highlights: [•] Different Barbarea spp., varieties, and types were used. [•] Glucosinolate and saponin content varied depending on the Barbarea plant. [•] Effects of plants on oviposition preference and survival of Plutella xylostella. [•] Plants showed different potential as dead-end trap crops for P. xylostella. [ABSTRACT FROM AUTHOR]

Abstract: The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), is an insect specialized on glucosinolate-containing Brassicaceae that uses glucosinolates in host-plant recognition. We used wild-type and mutants of Arabidopsis thaliana (L.) Heynh. (Brassicaceae) to investigate the interaction between plant glucosinolate and myrosinase content and herbivory by larvae of the generalist Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) and the specialist P. xylostella. We also measured glucosinolate changes as a result of herbivory by these larvae to investigate whether herbivory and glucosinolate induction had an effect on oviposition preference by P. xylostella. Feeding by H. armigera and P. xylostella larvae was 2.1 and 2.5 times less, respectively, on apk1 apk2 plants (with almost no aliphatic glucosinolates) than on wild-type plants. However, there were no differences in feeding by H. armigera and P. xylostella larvae on wild-type, gsm1 (different concentrations of aliphatic glucosinolates compared to wild-type plants), and tgg1 tgg2 plants (lacking major myrosinases). Glucosinolate induction (up to twofold) as a result of herbivory occurred in some cases, depending on both the plant line and the herbivore. For H. armigera, induction, when observed, was noted mostly for indolic glucosinolates, while for P. xylostella, induction was observed in both aliphatic and indolic glucosinolates, but not in all plant lines. For H. armigera, glucosinolate induction, when observed, resulted in an increase of glucosinolate content, while for P. xylostella, induction resulted in both a decrease and an increase in glucosinolate content. Two-choice tests with wild-type and mutant plants were conducted with larvae and ovipositing moths. There were no significant differences in preference of larvae and ovipositing moths between wild-type and gsm1 mutants and between wild-type and tgg1 tgg2 mutants. However, both larvae and ovipositing moths preferred wild-type over apk1 apk2 mutants. Two-choice oviposition tests were also conducted with P. xylostella moths comparing undamaged plants to plants being attacked by larvae of either P. xylostella or H. armigera. Oviposition preference by P. xylostella was unaffected as a result of larval plant damage, even in the cases where herbivory resulted in glucosinolate induction. [Copyright &y& Elsevier]

Abstract: Glucosinolates are plant secondary metabolites that are part of a plant defence system against pathogens and pests, the myrosinase-glucosinolate system, in which glucosinolates get activated by enzymic degradation through thioglucoside glucohydrolases called myrosinases. Epithiospecifier protein (ESP) and nitrile-specifier proteins (NSPs) divert myrosinase-catalyzed hydrolysis of a given glucosinolate from the formation of isothiocyanate to that of epithionitrile and/or nitrile. As the biological activity of glucosinolate hydrolysis products varies considerably, a detailed characterization of these specifier proteins is of utmost importance to understand their biological role. Therefore, the Arabidopsis thaliana AtNSP1, AtNSP2 and AtNSP5 and a supposed ancestor protein AtNSP-like1 were expressed in Escherichia coli and the activity of the purified recombinant proteins was tested in vitro on three highly different glucosinolates and compared to that of purified AtESP. As previously reported, only AtESP showed epithiospecifier activity on 2-propenylglucosinolate. We further confirmed that purified AtNSP1, AtNSP2 and AtNSP5, but not the ancestor AtNSP-like1 protein, show nitrile-specifier activity on 2-propenylglucosinolate and benzylglucosinolate. We now show for the first time that in vitro AtNSP1, AtNSP2 and AtNSP5 are able to generate nitrile from indol-3-ylmethylglucosinolate. We also tested the effect of different Fe(II) ion concentrations on the nitrile-specifier activity of purified AtNSP1, AtNSP2 and AtNSP5 on 2-propenylglucosinolate and benzylglucosinolate. AtNSP-related nitrile production was highly dependent on the presence of Fe(II) ions in the reaction assay. In the absence of added Fe(II) ions nitriles were only detected when benzylglucosinolate was incubated with AtNSP1. While AtNSP1 also exhibited overall higher nitrile-specifier activity than AtNSP2 and AtNSP5 at a given Fe(II) ion concentration, the pattern of nitrile formation in relation to Fe(II) ion concentrations depended on the AtNSP and the glucosinolate substrate. The pH of the solution also affected the reaction outcome, with a higher proportion of nitrile being produced at the higher pH for AtNSP2 and AtNSP5. [Copyright &y& Elsevier]

Abstract: Glucosinolates (GLS) are secondary plant metabolites that as a result of tissue damage, for example due to herbivory, are hydrolysed into toxic compounds that negatively affect generalist herbivores. Specialist herbivores have evolved specific adaptations to detoxify GLS or inhibit the formation of toxic hydrolytic products. Although rarely studied, GLS and their breakdown products may also affect parasitoids. The objectives were to test the effects of GLS in a multitrophic system consisting of the generalist herbivore Spodoptera exigua, the specialist herbivore Pieris rapae, and the endoparasitoid Hyposoter ebeninus. Three ecotypes of Arabidopsis thaliana that differ in their GLS composition and concentrations and one transformed line that constitutively produces higher concentrations of aliphatic GLS were used, the latter allowing a direct assessment of the effects of aliphatic GLS on insect performance. Feeding by the generalist S. exigua and the specialist P. rapae induced both higher aliphatic and indole GLS concentrations in the A. thaliana ecotypes, although induction was stronger for indole than aliphatic GLS. For both herbivores a negative correlation between performance and aliphatic GLS concentrations was observed. This suggests that the specialist, despite containing a nitrile-specifier protein (NSP) that diverts GLS degradation from toxic isothiocyanates to less toxic nitriles, cannot completely inhibit the formation of toxic GLS hydrolytic products, or that the costs of this mechanism are higher at higher GLS concentrations. Surprisingly, performance of the parasitoid was positively correlated with higher concentrations of aliphatic GLS in the plant, possibly caused by negative effects on host immune responses. Our study indicates that GLS can not only confer resistance against herbivores directly, but also indirectly by increasing the performance of the parasitoids of these herbivores. [Copyright &y& Elsevier]

Abstract: Glucosinolates are multi-functional plant secondary metabolites which play a vital role in plant defence and are, as dietary compounds, important to human health and livestock well-being. Knowledge of the tissue-specific regulation of their biosynthesis and accumulation is essential for plant breeding programs. Here, we report that in Arabidopsis thaliana, glucosinolates are accumulated differentially in specific cells of reproductive organs. Using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI), distribution patterns of three selected compounds, 4-methylsulfinylbutyl (glucoraphanin), indol-3-ylmethyl (glucobrassicin), and 4-benzoyloxybutyl glucosinolates, were mapped in the tissues of whole flower buds, sepals and siliques. The results show that tissue localization patterns of aliphatic glucosinolate glucoraphanin and 4-benzoyloxybutyl glucosinolate were similar, but indole glucosinolate glucobrassicin had different localisation, indicating a possible difference in function. The high resolution images obtained by a complementary approach, cryo-SEM Energy Dispersive X-ray analysis (cryo-SEM-EDX), confirmed increased concentration of sulphur in areas with elevated amounts of glucosinolates, and allowed identifying the cell types implicated in accumulation of glucosinolates. High concentration of sulphur was found in S-cells adjacent to the phloem in pedicels and siliques, indicating the presence of glucosinolates. Moreover, both MALDI MSI and cryo-SEM-EDX analyses indicated accumulation of glucosinolates in cells on the outer surface of the sepals, suggesting that a layer of glucosinolate-accumulating epidermal cells protects the whole of the developing flower, in addition to the S-cells, which protect the phloem. This research demonstrates the high potential of MALDI MSI for understanding the cell-specific compartmentation of plant metabolites and its regulation. [Copyright &y& Elsevier]

Abstract: By 2000, around 106 natural glucosinolates (GSLs) were probably documented. In the past decade, 26 additional natural GSL structures have been elucidated and documented. Hence, the total number of documented GSLs from nature by 2011 can be estimated to around 132. A considerable number of additional suggested structures are concluded not to be sufficiently documented. In many cases, NMR spectroscopy would have provided the missing structural information. Of the GSLs documented in the past decade, several are of previously unexpected structures and occur at considerable levels. Most originate from just four species: Barbarea vulgaris, Arabidopsis thaliana, Eruca sativa and Isatis tinctoria. Acyl derivatives of known GSLs comprised 15 of the 26 newly documented structures, while the remaining exhibited new substitution patterns or chain length, or contained a mercapto group or related thio-functionality. GSL identification methods are reviewed, and the importance of using authentic references and structure-sensitive detection methods such as MS and NMR is stressed, especially when species with relatively unknown chemistry are analyzed. An example of qualitative GSL analysis is presented with experimental details (group separation and HPLC of both intact and desulfated GSLs, detection and structure determination by UV, MS, NMR and susceptibility to myrosinase) with emphasis on the use of NMR for structure elucidation of even minor GSLs and GSL hydrolysis products. The example includes identification of a novel GSL, (R)-2-hydroxy-2-(3-hydroxyphenyl)ethylglucosinolate. Recent investigations of GSL evolution, based on investigations of species with well established phylogeny, are reviewed. From the relatively few such investigations, it is already clear that GSL profiles are regularly subject to evolution. This result is compatible with natural selection for specific GSL side chains. The probable existence of structure-specific GSL catabolism in intact plants suggests that biochemical evolution of GSLs has more complex implications than the mere liberation of a different hydrolysis product upon tissue disruption. [Copyright &y& Elsevier]

Abstract: Glucosinolates are sulphur-containing glycosides found in many Brassica spp. that are important because their aglycone hydrolysis products protect the plant from herbivores and exhibit anti-cancer properties in humans. Recently, synthetically produced selenium analogues have been shown to be more effective at suppressing cancers than their sulphur counterparts. Although selenium is incorporated into a number of Brassica amino acids and peptides, firm evidence has yet to be presented for the presence of selenium in the glucosinolates and their aglycones in planta. In this study broccoli and cauliflower florets, and roots of forage rape, all obtained from plants treated with sodium selenate, were analysed for the presence of organoselenides. GC–MS analysis of pentane/ether extracts identified six organoselenium compounds including selenium analogues of known myrosinase-derived Brassica volatiles: 4-(methylseleno)butanenitrile, 5-(methylseleno)pentanenitrile, 3-(methylseleno)propylisothiocyanate, 4-(methylseleno)butylisothiocyanate, and 5-(methylseleno)pentylisothiocyanate. LC–MS analysis of ethanolic extracts identified three selenoglucosinolates: 3-(methylseleno)propylglucosinolate (glucoselenoiberverin), 4-(methylseleno)butylglucosinolate (glucoselenoerucin), and 5-(methylseleno)pentylglucosinolate (glucoselenoberteroin). LC–MS/MS analysis was used to locate the position of the selenium atom in the selenoglucosinolate and indicates preferential incorporation of selenium via selenomethionine into the methylselenyl moiety rather than into the sulphate or β-thioglucose groups. In forage rape, selenoglucosinolates and their aglycones (mainly isothiocyanates), occurred at concentrations up to 10% and 70%, respectively, of their sulphur analogues. In broccoli, concentrations of the selenoglucosinolates and their aglycones (mainly nitriles) were up to 60% and 1300%, respectively of their sulphur analogues. These findings indicate the potential for the incorporation of high levels of selenium into Brassica glucosinolates. [Copyright &y& Elsevier]

Abstract: Glucosinolates (GLSs) are sulfur-rich plant secondary metabolites which occur in a variety of cruciferous vegetables and among various classes of them, genus Brassica exhibits a rich family of these phytochemicals at high, medium and low abundances. Liquid chromatography (LC) with electrospray ionization in negative ion mode (ESI-) coupled to a hybrid quadrupole linear ion trap (LTQ) and Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS) was employed for the selective and sensitive determination of intact GLSs in crude sample extracts of broccoli (Brassica oleracea L. Var. italica), cauliflower (B. oleracea L. Var. Botrytis) and rocket salad (Eruca sativa L.) with a wide range of contents. When LTQ and FTICR mass analyzers are compared, the magnitude of the limit of detection was ca. 5/6-fold lower with the FTICR MS. In addition, the separation and detection by LC–ESI-FTICR MS provides a highly selective assay platform for unambiguous identification of GLSs, which can be extended to lower abundance (minor) GLSs without significant interferences of other compounds in the sample extracts. The analysis of Brassicaceae species emphasized the presence of eight minor GLSs, viz. 1-methylpropyl-GLS, 2-methylpropyl-GLS, 2-methylbutyl-GLS, 3-methylbutyl-GLS, n-pentyl-GLS, 3-methylpentyl-GLS, 4-methylpentyl-GLS and n-hexyl-GLS. The occurrence of these GLSs belonging to the saturated aliphatic side chain families C4, C5 and C6, presumably formed by chain elongation of leucine, homoleucine and dihomoleucine as primary amino acid precursors, is described. Based on their retention behavior and tandem MS spectra, all these minor compounds occurring in plant extracts of B. oleracea L. Var. italica, B. oleracea L. Var. Botrytis and E. sativa L. were tentatively identified. [Copyright &y& Elsevier]

Abstract: Glucosinolates (GLs) present in root, seed, and leaf extracts of Pentadiplandra brazzeana Baillon were characterized and quantified according to the ISO 9167-1 method based on the HPLC analysis of desulfo-GLs. The analyses were complemented by GC–MS analyses of the isothiocyanates (ITCs) generated from GL degradation by myrosinase. Glucotropaeolin (1a), glucolimnanthin (2a), and glucoaubrietin (3a) were shown to be present in the root extract, whereas the seed mainly contained 3a. 3,4-Dimethoxybenzyl GL (4a), glucobrassicin (5a) and traces of 1a were detected in the leaf extract. The products were fully characterized as their desulfo-counterparts by spectroscopic techniques. [Copyright &y& Elsevier]

Abstract: Induced responses to insect herbivory are a common phenomenon in the plant kingdom. So far, induced responses have mostly investigated in aerial plant parts. Recently it was found that root herbivore may also elicit both local and systemic responses affecting aboveground herbivores and their natural enemies. Using broccoli (Brassica oleracea subsp. italica L.) and turnip (Brassica rapa subsp. rapa L.), two cultivated brassicaceaous plants differing in their chemistry and morphology, we analysed the local and systemic induced responses triggered by Delia radicum L. damage, JA and SA application. We also assessed whether the root induction treatments affected D. radicum larval performance. Both D. radicum damage and JA induced changes in glucosinolate and sugar content as well as affected D. radicum performance, while SA application did not. Despite the uniform chemical responses, the effect on larval performance on broccoli and turnip plants was very different. On broccoli, JA root treatment reduced herbivore performance, whereas in turnips the same treatment enhanced it. JA- and D. radicum-induced responses followed similar patterns, which suggests that the JA signalling pathway is involved in root-induced responses to larval feeding. Glucosinolate induction cannot fully explain the differences found in the performance of D. radicum on the different species. Changes in other resistance factors might significantly contribute to the induced resistance in these brassicaceaeous species as well. [Copyright &y& Elsevier]

Here we describe the structure elucidation and quantification of six glucosinolates (GSLs) from the roots of the desert plant Ochradenus baccatus , Delile 1813 (family Resedaceae; order Brassicales). The structure elucidation was established on the corresponding enzymatically desulfated derivatives of the native GSLs of the plant. Among these GSLs we describe the previously undescribed 2″- O -(α -L-arabinopyranosyloxy)benzylglucosinolate (1a), for which we propose the name glucoochradenin. The other five glucosinolates (2a - 6a) were (2S)-2-hydroxy-2-phenylethylglucosinolate (2a ; glucobarbarin), 2″- O -(α -L-rhamnopyranosyloxy)benzylglucosinolate (3a), benzylglucosinolate (4a ; glucotropaeolin), indol-3-ylmethylglucosinolate (5a ; glucobrassicin) and phenethylglucosinolate (6a ; gluconasturtiin), all elucidated as their desulfo-derivatives, 2b-6b respectively). Structures were elucidated by MS and 1D and 2D-NMR techniques, the identity of the arabinose verified by ion chromatography, and the absolute configuration of the sugar units determined by hydrolysis, coupling to cysteine methyl-ester and phenyl isothiocyanate followed by HPLC-MS analysis of the resulted diastereomers. Response factors were generated for desulfo-2″- O -(α -L-arabinopyranosyloxy)benzylglucosinolate and for desulfo-2″- O -(α -L-rhamnopyranosyloxy)benzylglucosinolate and all six GSLs were quantified, indicating that the root of O. baccatus is rich in GSLs (Avg. 61.3 ± 10.0 μmol/g DW and up to 337.2 μmol/g DW). [Display omitted] • Investigation of glucosinolate in Ochradenus baccatus , Resedaceae, Brassicales. • 6 glucosinolates desulfo-derivates isolated and quantified from O. baccatus roots. • O. baccatus roots contain up to 337 μmol/g DW GSLs. • High diversity in specific and total GSLs quantity. • Undescribed 2″-O-(α-L-arabinopyranosyloxy)benzylglucosinolate; TBN glucoochradenin. [ABSTRACT FROM AUTHOR]

Abstract: Glucosinolates represent a large group of plant natural products long known for diverse and fascinating physiological functions and activities. Despite the relevance and huge interest on the roles of indole glucosinolates in plant defense, little is known about their direct interaction with microbial plant pathogens. Toward this end, the metabolism of indolyl glucosinolates, their corresponding desulfo-derivatives, and derived metabolites, by three fungal species pathogenic on crucifers was investigated. While glucobrassicin, 1-methoxyglucobrassicin, 4-methoxyglucobrassicin were not metabolized by the pathogenic fungi Alternaria brassicicola, Rhizoctonia solani and Sclerotinia sclerotiorum, the corresponding desulfo-derivatives were metabolized to indolyl-3-acetonitrile, caulilexin C (1-methoxyindolyl-3-acetonitrile) and arvelexin (4-methoxyindolyl-3-acetonitrile) by R. solani and S. sclerotiorum, but not by A. brassicicola. That is, desulfo-glucosinolates were metabolized by two non-host-selective pathogens, but not by a host-selective. Indolyl-3-acetonitrile, caulilexin C and arvelexin were metabolized to the corresponding indole-3-carboxylic acids. Indolyl-3-acetonitriles displayed higher inhibitory activity than indole desulfo-glucosinolates. Indolyl-3-methanol displayed antifungal activity and was metabolized by A. brassicicola and R. solani to the less antifungal compounds indole-3-carboxaldehyde and indole-3-carboxylic acid. Diindolyl-3-methane was strongly antifungal and stable in fungal cultures, but ascorbigen was not stable in solution and displayed low antifungal activity; neither compound appeared to be metabolized by any of the three fungal species. The cell-free extracts of mycelia of A. brassicicola displayed low myrosinase activity using glucobrassicin as substrate, but myrosinase activity was not detectable in mycelia of either R. solani or S. sclerotiorum. [Copyright &y& Elsevier]

Abstract: In order to determine how plant uptake of a sulfur-rich secondary metabolite, sinalbin, affects the metabolic profile of sulfur-deficient plants, gas chromatography time-of-flight mass spectrometry (GC–TOF-MS), in combination with liquid chromatography–mass spectrometry (LC–MS), was used to survey the metabolome of Arabidopsis seedlings grown in nutrient media under different sulfur conditions. The growth media had either sufficient inorganic sulfur for normal plant growth or insufficient inorganic sulfur in the presence or absence of supplementation with organic sulfur in the form of sinalbin (p-hydroxybenzylglucosinolate). A total of 90 metabolites were identified by GC–TOF-MS and their levels were compared across the three treatments. Of the identified compounds, 21 showed similar responses in plants that were either sulfur deficient or sinalbin supplemented compared to sulfur-sufficient plants, while 12 metabolites differed in abundance only in sulfur-deficient plants. Twelve metabolites accumulated to higher levels in sinalbin-supplemented than in the sulfur-sufficient plants. Secondary metabolites such as flavonol conjugates, sinapinic acid esters and glucosinolates, were identified by LC–MS and their corresponding mass fragmentation patterns were determined. Under sinalbin-supplemented conditions, sinalbin was taken up by Arabidopsis and contributed to the endogenous formation of glucosinolates. Additionally, levels of flavonol glycosides and sinapinic acid esters increased while levels of flavonol diglycosides with glucose attached to the 3-position were reduced. The exogenously administered sinalbin resulted in inhibition of root and hypocotyl growth and markedly influenced metabolite profiles, compared to control and sulfur-deficient plants. These results indicate that, under sulfur deficient conditions, glucosinolates can be a sulfur source for plants. This investigation defines an opportunity to elucidate the mechanism of glucosinolate degradation in vivo. [Copyright &y& Elsevier]

Abstract: Glucosinolates, amino acid-derived thioglycosides found in plants of the Brassicales order, are one of the best studied classes of plant secondary metabolites. Together with myrosinases and supplementary proteins known as specifier proteins, they form the glucosinolate–myrosinase system that upon tissue damage gives rise to a number of biologically active glucosinolate breakdown products such as isothiocyanates, epithionitriles and organic thiocyanates involved in plant defense. While isothiocyanates are products of the spontaneous rearrangement of the glucosinolate aglycones released by myrosinase, the formation of epithionitriles and organic thiocyanates depends on both myrosinases and specifier proteins. Hydrolysis product profiles of many glucosinolate-containing plant species indicate the presence of specifier proteins, but only few have been identified and characterized biochemically. Here, we report on cDNA cloning, heterologous expression and characterization of TaTFP, a thiocyanate-forming protein (TFP) from Thlaspi arvense L. (Brassicaceae), that is expressed in all plant organs and can be purified in active form after heterologous expression in Escherichia coli. As a special feature, this protein promotes the formation of allylthiocyanate as well as the corresponding epithionitrile upon myrosinase-catalyzed hydrolysis of allylglucosinolate, the major glucosinolate of T. arvense. All other glucosinolates tested are converted to their simple nitriles when hydrolyzed in the presence of TaTFP. Despite its ability to promote allylthiocyanate formation, TaTFP has a higher amino acid sequence similarity to known epithiospecifier proteins (ESPs) than to Lepidium sativum TFP. However, unlike Arabidopsis thaliana ESP, its activity in vitro is not strictly dependent on Fe2+ addition to the assay mixtures. The availability of TaTFP in purified form enables future studies to be aimed at elucidating the structural bases of specifier protein specificities and mechanisms. Furthermore, identification of TaTFP shows that product specificities of specifier proteins can not be predicted based on amino acid sequence similarity and raises interesting questions about specifier protein evolution. [Copyright &y& Elsevier]

Abstract: The glucosinolate–myrosinase system found in plants of the Brassicales order is one of the best studied plant chemical defenses. Glucosinolates and their hydrolytic enzymes, myrosinases, are stored in separate compartments in the intact plant tissue. Upon tissue disruption, bioactivation of glucosinolates is initiated, i.e. myrosinases get access to their glucosinolate substrates, and glucosinolate hydrolysis results in the formation of toxic isothiocyanates and other biologically active products. The defensive function of the glucosinolate–myrosinase system has been demonstrated in a variety of studies with different insect herbivores. However, a number of generalist as well as specialist herbivores uses glucosinolate-containing plants as hosts causing large agronomical losses in oil seed rape and other crops of the Brassicaceae. While our knowledge of counteradaptations in generalist insect herbivores is still very limited, considerable progress has been made in understanding how specialist insect herbivores overcome the glucosinolate–myrosinase system and even exploit it for their own defense. All mechanisms of counteradaptation identified to date in insect herbivores specialized on glucosinolate-containing plants ensure that glucosinolate breakdown to toxic isothiocyanates is avoided. This is accomplished in many different ways including avoidance of cell disruption, rapid absorption of intact glucosinolates, rapid metabolic conversion of glucosinolates to harmless compounds that are not substrates for myrosinases, and diversion of plant myrosinase-catalyzed glucosinolate hydrolysis. One of these counteradaptations, the nitrile-specifier protein identified in Pierid species, has been used to demonstrate mechanisms of coevolution of plants and their insect herbivores. [Copyright &y& Elsevier]

Abstract: Plants are faced with a trade-off between on the one hand growth, development and reproduction and on the other hand defence against environmental stresses. Yet, research on insect–plant interactions has addressed plant–pollinator interactions and plant–attacker interactions separately. Plants have evolved a high diversity of constitutive and induced responses to attack, including the systemic emission of herbivore-induced plant volatiles (HIPVs). The effect of HIPVs on the behaviour of carnivorous insects has received ample attention for leaf-feeding (folivorous) species and their parasitoids and predators. Here, we review whether and to what extent HIPVs affect the interaction of plants in the flowering stage with mutualistic and antagonistic insects. Whereas the role of flower volatiles in the interactions between plants and insect pollinators has received increased attention over the last decade, studies addressing both HIPVs and pollinator behaviour are rare, despite the fact that in a number of plant species herbivory is known to affect flower traits, including size, nectar secretion and composition. In addition, folivory and florivory can also result in significant changes in flower volatile emission and in most systems investigated, pollinator visitation decreased, although exceptions have been found. Negative effects of HIPVs on pollinator visitation rates likely exert negative selection pressure on HIPV emission. The systemic nature of herbivore-induced plant responses and the behavioural responses of antagonistic and mutualistic insects, requires the study of volatile emission of entire plants in the flowering stage. We conclude that approaches to integrate the study of plant defences and pollination are essential to advance plant biology, in particular in the context of the trade-off between defence and growth/reproduction. [Copyright &y& Elsevier]

Abstract: Five acylated glucosinolates (GSLs) were isolated as desulfated derivatives after enzymatic desulfation of anionic metabolites from seeds of two chemotypes of Barbarea vulgaris, and their structures were elucidated by a combination of spectroscopic methods and HPLC analysis of products of enzymatic de-acylation. The acyl group was in all cases found to be a trans isoferuloyl group at the 6′-position of the thioglucose moiety. The GSL moieties of the native metabolites were found to be one Trp derived; indol-3-ylmethylGSL, as well as four homoPhe derived; phenethylGSL, (S)-2-hydroxy-2-phenylethylGSL, (R)-2-hydroxy-2-phenylethylGSL, and (R)-2-hydroxy-2-(4-hydroxyphenyl)ethylGSL. GSL analysis of B. vulgaris seed extracts by the commonly employed ‘desulfoGSL’ method (based on binding to anion exchange columns, enzymatic desulfation, elution and HPLC) was optimized for 6′-isoferuloyl derivatives of GSLs. From peak areas before and after de-acylation of the isolated desulfoGSL, the response factor of the 6′-isoferuloyl derivative of (S)-2-hydroxy-2-phenylethylGSL was estimated to be 0.37 (relative to 1.00 for sinigrin), allowing us to estimate the level in B. vulgaris to 3μmol/g dry wt. in mature seeds and less than 0.1μmol/g dry wt. in seedlings and floral parts of the insect resistant G-type of B. vulgaris var. arcuata. HPLC analysis of intact GSLs in crude extracts and after group separation did not reveal additional derivatives, but confirmed the existence of the deduced intact GSLs. A taxonomic screen showed that most (14/17) B. vulgaris accessions (with the exception of three accessions of var. vulgaris) contained relatively high levels of 6′-isoferuloyl GSLs. The profiles of 6′-isoferuloylated GSLs matched the profiles of non-acylated GSLs in the same seed accessions, suggesting a low side chain specificity of the isoferuloylation mechanism. A minor peak tentatively identified as a dimethoxycinnamoyl derivative of (S)-2-hydroxy-2-phenylethylGSL was detected by HPLC-MS of one accession, suggesting that GSLs with other acyl groups may occur at low levels. A single analyzed B. plantaginae accession contained relatively high levels of 6′-isoferuloylated phenethylGSL and (S)-2-hydroxy-2-phenylethylGSL. Five other tested Barbarea species (B. australis, B. bracteosa, B. intermedia, B. stricta, B. verna) also contained isoferuloylated GSLs, albeit at lower levels than in B. vulgaris and B. plantaginae, suggesting that seed GSL acylation is a general character of the Barbarea genus and possibly also of related genera including Arabidopsis. [Copyright &y& Elsevier]

Abstract: In this review, we provide an overview of the role of glucosinolates and other phytochemical compounds present in the Brassicaceae in relation to plant protection and human health. Current knowledge of the factors that influence phytochemical content and profile in the Brassicaceae is also summarized and multi-factorial approaches are briefly discussed. Variation in agronomic conditions (plant species, cultivar, developmental stage, plant organ, plant competition, fertilization, pH), season, climatic factors, water availability, light (intensity, quality, duration) and CO2 are known to significantly affect content and profile of phytochemicals. Phytochemicals such as the glucosinolates and leaf surface waxes play an important role in interactions with pests and pathogens. Factors that affect production of phytochemicals are important when designing plant protection strategies that exploit these compounds to minimize crop damage caused by plant pests and pathogens. Brassicaceous plants are consumed increasingly for possible health benefits, for example, glucosinolate-derived effects on degenerative diseases such as cancer, cardiovascular and neurodegenerative diseases. Thus, factors influencing phytochemical content and profile in the production of brassicaceous plants are worth considering both for plant and human health. Even though it is known that factors that influence phytochemical content and profile may interact, studies of plant compounds were, until recently, restricted by methods allowing only a reductionistic approach. It is now possible to design multi-factorial experiments that simulate their combined effects. This will provide important information to ecologists, plant breeders and agronomists. [Copyright &y& Elsevier]

Abstract: Combined genomics and metabolomics approaches were used to unravel molecular mechanisms behind interactions between winter cress (Barbarea vulgaris) and flea beetle (Phyllotreta nemorum). B. vulgaris comprises two morphologically, biochemically and cytologically deviating types, which differ in flea beetle resistance, saponin and glucosinolate profiles, as well as leaf pubescence. An F2 population generated from a cross between the two B. vulgaris types was used to construct a B. vulgaris genetic map based on 100 AFLP and 31 microsatellite markers. The map was divided into eight linkage groups. QTL (quantitative trait loci) analysis revealed a total of 15 QTL affecting eight traits, including nine QTL for four saponins, two QTL for two glucosinolates, two QTL for hairiness, and two QTL for flea beetle resistance. The two QTL for resistance towards flea beetles in B. vulgaris co-localized with QTL for the four saponins associated with resistance. Furthermore, global QTL analysis of B. vulgaris metabolites identified QTL for a number of flavonoid glycosides and additional saponins from both resistant and susceptible types. The transcriptome of the resistant B. vulgaris type was sequenced by pyrosequencing, and sequences containing microsatellites were identified. Microsatellite types in B. vulgaris were similar to Arabidopsis thaliana but different from Oryza sativa. Comparative analysis between B. vulgaris and A. thaliana revealed a remarkable degree of synteny between a large part of linkage groups 1 and 4 of B. vulgaris harboring the two QTL for flea beetle resistance and Arabidopsis chromosomes 3 and 1. Gene candidates that may underlie QTL for resistance and saponin biosynthesis are discussed. [ABSTRACT FROM AUTHOR]