High Levels Of Glucosinolates Research Articles

Effects of glucosinolate and myrosinase levels in Brassica juncea on a glucosinolate-sequestering herbivore – and vice versa

Larvae of the turnip sawfly, Athalia rosae L. (Hymenoptera: Tenthredinidae), sequester glucosinolates of their host plants, namely members of the Brassicaceae family, in their haemolymph. Therefore, they need to circumvent myrosinase activities of the plant tissue which normally hydrolyse the glucosinolates after plant damage. Effects of varying levels of glucosinolates and myrosinases on the performance of A. rosae were investigated using homozygous lines of Brassica juncea (L.) with either (1) low glucosinolate (lowGS) and low myrosinase (lowMR), (2) high glucosinolate (highGS) and high myrosinase (highMR), or (3) high glucosinolate (highGS) and low myrosinase (lowMR) levels. To insure that the given quantities remained as constant as possible, newly hatched larvae were enclosed on the second-youngest leaf of a plant, and were offered a new plant of comparable physiological age (6-leaf-stage) every day. The performance of A. rosae was little affected by leaf quality. Body masses of eonymphs and adults were on average lowest on the highGS/highMR-line, but these differences were rarely significant. The pupal developmental times of females and males were longest on the highGS/lowMR-line in only one of two replicate experiments. All other performance traits (developmental times of larvae, egg numbers, adult longevity) were not significantly different. Glucosinolates, sequestered by the larvae, are carried through the pupal stage. The glucosinolate concentration measured in adult insects reflected the level of the host plant line, without showing any obvious costs for sequestration. Obviously, A. rosae is highly tolerant to variation in the glucosinolate-myrosinase system of its host.

Altering glucosinolate profiles modulates disease resistance in plants

Plant diseases are major contributing factors for crop loss in agriculture. Here, we show that Arabidopsis plants with high levels of novel glucosinolates (GSs) as a result of the introduction of single CYP79 genes exhibit altered disease resistance. Arabidopsis expressing CYP79D2 from cassava accumulated aliphatic isopropyl and methylpropyl GS, and showed enhanced resistance against the bacterial soft-rot pathogen Erwinia carotovora, whereas Arabidopsis expressing the sorghum CYP79A1 or over-expressing the endogenous CYP79A2 accumulated p-hydroxybenzyl or benzyl GS, respectively, and showed increased resistance towards the bacterial pathogen Pseudomonas syringae. In addition to the direct toxic effects of GS breakdown products, increased accumulation of aromatic GSs was shown to stimulate salicylic acid-mediated defenses while suppressing jasmonate-dependent defenses, as manifested in enhanced susceptibility to the fungus Alternaria brassicicola. Arabidopsis with modified GS profiles provide important tools for evaluating the biological effects of individual GSs and thereby show potential as biotechnological tools for the generation of plants with tailor-made disease resistance.

Quantitative genetic analysis of total glucosinolate, oil and protein contents in Ethiopian mustard (<I>Brassica carinata</I> A. Braun)

Cultivars of Ethiopian mustard are agronomically robust, but have very high levels of total glucosinolates, which impair feed value of the meal though it is rich in protein of balanced amino acids. This experiment was undertaken to assess the level of natural variation in total glucosinolate, and study its inheritance together with that of oil and protein from a diallel cross of six inbred lines which were field-tested in a randomized block design at two locations in Ethiopia. Seeds were analyzed using HPLC (glucosinolates), NMR (oil) and NIRS (protein). Analyses of variance, Hayman's method of diallel analysis and a mixed linear model of genetic analysis were employed to estimate and predict genetic parameters and interactions. There were significant differences among the parental lines as well as their hybrids. The additive, dominance and cytoplasmic effects were highly significant for all the traits. The additive component of variance, accounting for about 40% of the total variations in all the traits, was twice as much as the dominance, which in turn was also about twice as much as the variation accounted by the cytoplasm. A clear-cut case of inbreeding depression was evident with oil content. Partial dominance was most prevalent in governing total glucosinolate although some levels of over-dominance were also noticed. It appeared that in addition to nuclear genes, cytoplasmic components, which could be persistent or transient maternal effects, are also of significance in the inheritances of these quantitative traits in B. carinata . There were at least two dominant genes with decreasing effect on total glucosinolate for every single recessive gene of counter actions. The predominant additive component of variation coupled with the high narrow-sense heritability may allow fixation of low levels of total glucosinolate in recombinant inbred lines by selection. Keywords : Brassica carinata , diallel cross, glucosinolates, oil, protein SINET: Ethiopian Journal of Science Vol. 28(2) 2005: 141-150

Effects of Brassica vegetable juice on the induction of apoptosis and aberrant crypt foci in rat colonic mucosal crypts in vivo.

Glucosinolates are sulfur-containing glycosides found in the Brassica vegetables. Their breakdown products include isothiocyanates, which are produced following exposure to the endogenous plant enzyme myrosinase. Isothiocyanates are pungent, biologically active compounds that suppress carcinogenesis in vivo, and induce apoptosis in vitro. We have shown previously that oral administration of the isolated glucosinolate sinigrin induces apoptosis, and suppresses aberrant crypt foci in the colonic mucosa of rats treated previously with 1,2-dimethylhydrazine (DMH). In this study we explored the effects of both raw and thermally processed Brussels sprout tissue on the modulation of crypt cell apoptosis and mitosis, and the frequency of aberrant crypt foci in the colon. Freeze-dried raw and microwave-cooked Brussels sprouts contained high levels of intact glucosinolates, but they were absent from freshly prepared sprout juice. Oral administration of uncooked Brussels sprouts, whether as a juice, or as a freeze-dried powder, was associated with significantly enhanced levels of apoptosis and reduced mitosis in the colonic crypts. However, this effect was confined to rats previously injected (48 h) with DMH, in which levels of apoptosis and mitosis following DNA damage were already high. There was no effect of treatment in control animals. There was also little evidence of these effects when intact glucosinolates were administered in blanched sprout tissue, which lacked active myrosinase. We conclude that glucosinolate breakdown products derived from Brassica vegetables can exert a profound effect on the balance of colorectal cell proliferation and death in an animal model of colorectal neoplasia.

The biology of Canadian weeds. 9. Thlaspi arvense L. (updated)

An updated review of biological information is provided for Thlaspi arvense. Native to Eurasia, the species is naturalized and widely spread in temperate regions of the northern hemisphere, including all of Canada's provinces and territories, and has recently spread to temperate regions in the southern hemisphere. It is an annual pioneer of disturbed soils and is an important weed of grain, oilseed, and forage crops in Canada, particularly in the prairies. High levels of erucic acid and glucosinolates can contaminate canola. When present in hay or other fodder, its seeds or leaves can be toxic to animals, as well as contaminate milk and meat with unpleasant flavors. It can serve as a host for insect, nematode, fungal and viral pests of canola and mustard crops. A persistent seed bank, high fecundity, and the growth habit of a hardy winter annual with early- (EF) and late-flowering (LF) strains, all contribute to its ability to compete with crops. Effective herbicides include the sulfonylureas, chlorsulfuron and ethametsulphuron, MCPA, tribenuronmethyl, phenocyacetic acid, flurtamone, 2,4-D, 2,4-D + dicamba, and 2,4-D + picloram. A resistant biotype to Group 2 herbicides, which inhibit acetolactate synthase (ALS), has been found at two to five sites in Alberta in 2001. The potential of T. arvense as an industrial oilseed crop is being investigated. Key words: Stinkweed, Thlaspi arvense, weed biology, field pennycress, fanweed, oilseed potential

Comparative Analysis of Quantitative Trait Loci Controlling Glucosinolates, Myrosinase and Insect Resistance in Arabidopsis thaliana

Evolutionary interactions among insect herbivores and plant chemical defenses have generated systems where plant compounds have opposing fitness consequences for host plants, depending on attack by various insect herbivores. This interplay complicates understanding of fitness costs and benefits of plant chemical defenses. We are studying the role of the glucosinolate-myrosinase chemical defense system in protecting Arabidopsis thaliana from specialist and generalist insect herbivory. We used two Arabidopsis recombinant inbred populations in which we had previously mapped QTL controlling variation in the glucosinolate-myrosinase system. In this study we mapped QTL controlling resistance to specialist (Plutella xylostella) and generalist (Trichoplusia ni) herbivores. We identified a number of QTL that are specific to one herbivore or the other, as well as a single QTL that controls resistance to both insects. Comparison of QTL for herbivory, glucosinolates, and myrosinase showed that T. ni herbivory is strongly deterred by higher glucosinolate levels, faster breakdown rates, and specific chemical structures. In contrast, P. xylostella herbivory is uncorrelated with variation in the glucosinolate-myrosinase system. This agrees with evolutionary theory stating that specialist insects may overcome host plant chemical defenses, whereas generalists will be sensitive to these same defenses.

Brassica crops and a <i>Streptomyces sp</i> as potential biocontrol for clubroot of brassicas

Two glasshouse experiments and a field trial were carried out to evaluate the potential of brassica crops which contain high levels of glucosinolates for control of clubroot of brassicas Brassica rapa crops were grown for about 70 days in a field which was infested with Plasmodiophora brassicae In the first glasshouse experiment the leaf and stem of the plants were harvested chopped into small pieces and mixed with clubrootinfested soil in punnets Chinese cabbage seedlings were then transplanted into the punnets In the second glasshouse experiment soil samples were taken in punnets from plots where the B rapa crops had been rotary hoed and left to decompose for about three weeks Chinese cabbage seedlings were transplanted into the punnets In both experiments B rapatreated soil reduced (P

Inheritance of root glucosinolate content in canola

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Rapeseed meal‐glucosinolates and their antinutritional effects. Part II. Flavour and palatability

AbstractThis paper has reviewed the current literature relating to the effects of glucosinolates on the palatability of rapeseed meal. The available evidence indicates that diet palatability can be adversely affected by rapeseed meal inclusion and that this response is related to glucosinolate level. However the response is variable and depends also on the species of animal, age and growth state. Younger animals, particularly chicks, piglets and calves appear to be more severely affected and exhibit reduced intake and hence depressed performance with diets containing high levels of glucosinolates from high glucosinolate rapeseed meal. Palatability is substantially improved by the use of low glucosinolate rapeseed meal (LG‐RSM) containing 10–30 μ/g and very low glucosinolate rapeseed meal (VLG‐RSM) containing 1–5 μ/g glucosinolates. From the findings of this review, it can be concluded that LG‐RSM and VLG‐RSM can be included at levels up to 20% and 30% for calves and dairy cows respectively. Since piglets are particularly sensitive it is suggested that rapeseed is excluded from early starter diets but that low glucosinolate meals can be included at levels of 10% and 15% for grower and finisher pigs respectively. Growing poultry may be less sensitive to palatability problems associated with rapeseed meal but the use of high levels is constrained due to the lower energy and higher fibre contents of RSM compared with soybean meal.

Rapssaaten und Rapsprodukte im Mischfutter

AbstractZur Analyse des Einsatzes von 00‐Rapssaat in energiereiche Futtermischungen wurde die Wirkung hydrothermischer und rein thermischer (Infrarot‐ und Heißluft‐) Vorbehandlungen auf die Erhöhung der Fettverfügbarkeit, Reduzierung des Glucosinolatgehaltes und Veränderungen der Proteinlöslichkeit in Wasser sowie Pelletabriebfestigkeit im kleintechnischen Maßstab untersucht. Hydrothermische und rein thermische Vorbehandlungen führen zu unbedeutenden Erhöhungen der Fettverfügbarkeit, aber zur weiteren Reduzierung des Glucosinolatgehaltes, der auch bei 00‐Rapssaat schwanken und über den Grenzwerten liegen kann. Erst eine nachfolgende mechanische Beanspruchung (Quetschen) läßt bei intensiver thermischer Vorbehandlung Fettverfügbarkeiten über 80% erreichen. Zur Vermeidung einer Absenkung der Proteinlöslichkeit in Wasser unter 10% erweist sich eine kurze und intensive Behandlung (z. B. Infrarotbehandlung) als vorteilhaft. Die Pelletabriebfestigkeit von Mischfutter mit flockierter 00‐Rapssaat ist beser als jene mit Rapsextraktionsschrot und Zusatz von freiem Futterfett bei gleichem Gesamtfettgehalt.

Glucosinolates and Resistance to Leptosphaeria maculans in Wild and Cultivated Brassica Species

AbstractSynthetic lines of Brassica napus were derived by combining the genomes of B. atlantica and B. oleracea var. alboglabra, which were respectively resistant and susceptible to foliar infection by Leptosphaeria maculans, with a susceptible line of B. rapa. Resistance was expressed in the synthetic lines containing the genome of B. atlantica. The high levels of alkenyl glucosinolates which occur in leaves of B. atlantica, and which have been implicated in disease resistance, were also expressed within the synthetic lines, although the dominant glucosinolate had changed from sinigrin to glucobrassicanapin. Disease resistance and glucosinolate profiles did not co‐segregate in F2 progeny from crosses between the synthetic lines.

Comparison of Oilseed Brassica Crops with High or Low Levels of Glucosinolates and Alfalfa as Hosts for Three Species of Lygus (Hemiptera: Heteroptera: Miridae)

The suitability of oilseed rapes, Brassica spp., and alfalfa, Medicago sativa L., as host plants for Lygus spp. is compared. Lygus bugs were monitored in field plots of five cultivars of oilseed rape, Brassica napus L. and Brassica campestris L., containing high or low levels of glucosinolates. The number of Iygus collected did not differ among cultivars of the same species. Nymphs reared in the laboratory on the five cultivars had the same survival and developmental rate regardless of the glucosinolate status of the cultivar. Survival, development, and growth were compared for nymphs reared on excised stem tips of oilseed rape and alfalfa that had flower buds or flowers. Nymphs developed faster and had higher survival when reared on oilseed rape than when reared on alfalfa. However, the dry weights of adults collected from an alfalfa field were significantly higher than those reared on alfalfa in the laboratory, indicating that excised alfalfa may not be as good a source of food for conducting laboratory tests as excised oilseed rape. Adult weights of field-collected Iygus bugs from alfalfa and oilseed rape did not differ significantly. The results demonstrate that oilseed rapes with high or low levels of glucosinolates are both suitable hosts for the three species of Iygus, and as suitable as alfalfa. Furthermore, the change from the older highglucosinolate rape cultivars to the low-glucosinolate cultivars that are now widely grown probably had no effect on the suitability of the crop for Iygus bugs.

Alkenyl Glucosinolate Levels in Androgenic Populations of Brassica napus

AbstractThe levels of individual and total alkenyl glucosinolates in seeds of microspore‐derived spontaneous diploid plants from low by high and low by low glucosinolate parent crosses were examined to assess the utility of haploidy in canola breeding. The distributions of lines in the populations supported previous proposals that alkenyl glucosinolate levels are under multigenic control. Levels of all of the individual glucosinolates were positively correlated and were significantly reduced in canola‐quality material in comparison to rapeseed‐quality material. The populations of microspore‐derived lines from low × high crosses were skewed to high glucosinolate levels but the population from a low × low glucosinolate cross had a greater proportion of low glucosinolate lines. The former observations can be explained in terms of the dominance of genes for high glucosinolate levels in Brassica napus. The present findings contradict previous reports that androgenic lines have higher glucosinolate content than the parents and in fact, haploidy may select for low glucosinolate lines when crosses between low glucosinolate parents are used.

Studies on the Effects of Rapeseed Meal on Thyroid Status of Cattle, Glucosinolate and Iodine Content of Milk and Other Parameters

The effects of feeding rapeseed meals (RSM) containing low (Tower) or high (Target/Turret) levels of glucosinolates on thyroid status, iodine and glucosinolate content of milk and other parameters were studied in dairy cows and young calves. RSM (Tower and Turret) fed to dairy cows at 25% of the grain mixture reduced iodine content of milk. Diets containing Tower and Turret RSM tended to reduce plasma thyroxine (T4) in cows and increase the size of thyroids in rats. Calf diets containing Target and Tower RSM resulted in increased liver and thyroid weights, but only those containing Target tended to reduce plasma T4 levels. Feed intake, weight gain, hemoglobin, blood cell volume and erythrocyte count in calves were not affected by diets containing Tower RSM, but Target RSM reduced all these parameters. In addition, diets containing Target caused more pronounced histological changes of the calves' thyroid than those containing Tower RSM. No measurable amounts of intact glucosinolates were detected in milk of cows fed RSM. Similarly the glucosinolate aglucones, isothiocyanates or vinyl oxazolidinethione, were not transferred to milk although small amounts of unsaturated nitrile (1-cyano-2-hydroxy-3-butene) and inorganic thiocyanate were detected in milk. Rats receiving milk from cows fed Turret RSM developed larger thyroid than those receiving milk from control-fed cows. Supplemental iodine (61.0 microgram/d) in the rat prevented the thyroid enlargement.