Soil-borne microorganisms and soil-type affect pyrrolizidine alkaloids in Jacobaea vulgaris

Secondary metabolites like pyrrolizidine alkaloids (PAs) play a crucial part in plant defense. We studied the effects of soil-borne microorganisms and soil-type on pyrrolizidine alkaloids in roots and shoots of Jacobaea vulgaris. We used clones of two genotypes from a dune area (Meijendel), propagated by tissue culture and grown on two sterilized soils and sterilized soils inoculated with 5% of non-sterilized soil of either of the two soil-types. Soil-borne microorganisms and soil-type affected the composition of PAs. By changing the composition rather than the total concentration below and aboveground, plants have a more complex defense strategy than formerly thought. Interestingly, a stronger negative effect on plant growth was found in sterilized soils inoculated with their ‘own’ microbial community suggesting that pathogenic and/or other plant inhibiting microorganisms were adapted to their ‘own’ soil conditions

Dutch survey pyrrolizidine alkaloids in animal forage

Pyrrolizidine alkaloids (PAs) are secondary plant metabolites produced by a number of plants from the Asteraceae (Compositae), Boriginaceae and Fabaceae (Leguminosae) families. Many of these alkaloids have been shown to be highly toxic, causing hepatic veno-occlusive disease (VOD), liver cirrhosis and ultimately death. PAs may have also mutagenic and carcinogenic potential. Amongst livestock, cattle and horses are especially susceptible to the toxic effects of the PAs. Humans may also be at risk by the consumption of milk of livestock fed with PA-contaminated forage. At RIKILT - Institute of Food Safety a (semi)quantitative method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of PAs in animal feeds has been developed and validated. This method comprises 40 macrocyclic PAs (including tertiary amines and N-oxides) representative for ragwort species. The method has been used for the analysis of 147 forage samples collected in 2006-2008

The Relationship between Structurally Different Pyrrolizidine Alkaloids and Western Flower Thrips Resistance in F2 Hybrids of Jacobaea vulgaros and Jacobaea aquatica

Segregating plant hybrids often have more ecological and molecular variability compared to parental species, and are therefore useful for studying relationships between different traits, and the adaptive significance of trait variation. Hybrid systems have been used to study the relationship between the expression of plant defense compounds and herbivore susceptibility. We conducted a western flower thrips (WFT) bioassay using a hybrid family and investigated the relationship between WFT resistance and pyrrolizidine alkaloid (PA) variation. The hybrid family consisted of two parental (Jacobaea vulgaris and Jacobaea aquatica) genotypes, two F1 genotypes, and 94 F2 hybrid lines. The J. aquatica genotype was more susceptible to thrips attack than the J. vulgaris genotype, the two F1 hybrids were as susceptible as J. aquatica, and susceptibility to WFT differed among F2 hybrid lines: 69 F2 lines were equally susceptible compared to J. aquatica, 10 F2 lines were more susceptible than J. aquatica and 15 F2 lines were as resistant as J. vulgaris or were intermediate to the two parental genotypes. Among 37 individual PAs that were derived from four structural groups (senecionine-, jacobine-, erucifoline- and otosenine-like PAs), the N-oxides of jacobine, jaconine, and jacoline were negatively correlated with feeding damage caused by WFT, and the tertiary amines of jacobine, jaconine, jacoline, and other PAs did not relate to feeding damage. Total PA concentration was negatively correlated with feeding damage. Among the four PA groups, only the total concentration of the jacobine-like PAs was negatively correlated with feeding damage. Multiple regression tests suggested that jacobine-like PAs play a greater role in WFT resistance than PAs from other structural groups. We found no evidence for synergistic effects of different PAs on WFT resistance. The relationship between PA variation and WFT feeding damage in the Jacobaea hybrids suggests a role for PAs in resistance to generalist insects

Effects of plant diversity on the concentration of secondary plant metabolites and the density of arthropods on focal plants in the field

Plant science

Application of methyl jasmonate and salicylic acid lead to contrasting effects on the plant's metabolome and herbivory

Plant science

Synthesis of 8-, 9-, 12-, and 13-mono-13C-retinal

Bio-organic Synthesi

The analysis of lipophilic marine toxins

Consumption of lipophilic marine toxin contaminated shellfish can lead to severe intoxications. Methods described in European Union (EU) legislation to test for the presence of these toxins are based on a mouse or rat bioassay. These assays are unethical and have a poor sensitivity and selectivity. For this reason there is an urgent need for alternative methods. Most promising alternatives are the methods based on liquid chromatography - tandem mass spectrometry (LC-MS/MS). A LC-MS/MS method with alkaline chromatographic conditions in which we were able to separate and analyze the most important toxins in a single analysis was developed. Furthermore, a clean up procedure based on solid phase extraction (SPE) was developed. A combination of SPE clean up and alkaline chromatographic conditions resulted in reduced matrix effects for all matrices tested (mussel, scallop and oyster). The developed SPE & LC-MS/MS method was in-house validated using EU Commission Decision 2002/657/EC. With respect to accuracy, repeatability, reproducibility and decision limit the method performed well. The method also performed excellently in view of possible new limits that are 4- to 5-fold lower than current limits for some toxins. A collaborative study was also performed for the most important toxins of the lipophilic marine toxin group

Seasonal variation in defence compounds: a case study on pyrrolizidine alkaloids of clones of Jacobaea vulgaris, Jacobaea aquatica and their hybrids

Plant science

The evolution of pyrrolizidine alkaloid diversity among and within Jacobaea species

Plant science