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Background:Hybridisation inSenecio/Jacobaeais frequent and of significance in speciation and evolution. Moreover, these genera are model systems for studying the evolution of pyrrolizidine alkaloids (PAs). Hybrids betweenJacobaea aquaticaandJ. vulgarishave been reported from north-western Europe. Aims:Our aim was to determine whether hybrids betweenJacobaea aquaticaandJ. vulgarisalso occurred in Austria, and if these hybrids could be responsible for the presumed increase ofJ. aquatica-like plants in this part of Europe. Furthermore, we tested if such hybrids showed an altered PA spectrum compared with parental species. Methods:We used amplified fragment length polymorphisms (AFLPs) to analyse genetic diversity and structure, and gas chromatography–mass spectrometry (GC–MS) to identify PAs. Results:We were able to identify genetically one hybrid population adjacent to a largeJ. aquaticapopulation. The AFLP phenotypes of hybrids demonstrated a closer relationship toJ. aquatica, suggesting frequent backcrossing. All hybrid individuals contained the same set of PAs as the parental species, but in differing amounts, plus four additional PAs, one of which may be novel. Conclusions:Although hybridisation inJacobaeais common, we were able to confirm only one hybrid population in Austria. Therefore, it seems unlikely that hybridisation plays a role in the presumed increase ofJ. aquaticain this area. [ABSTRACT FROM AUTHOR]

The toxic pyrrolizidine alkaloids (PAs) senecionine and integerrimine are minor compounds in the rhizomes of the medicinal plant Petasites hybridus. Plants used in phytopharmacy should be as low in PAs as possible. The present work investigates whether the PA content of the rhizomes can be lowered in the progenies obtained from selected plants through experimental crossings. Starting from plants differing in the PA content, two consecutive crossing generations (F1 and F2) were established. The PAs were recorded in the young runners of the rhizome. The results showed that various progenies differed clearly in their PA content and even within a progeny the PA content may vary considerably. Plants poor in alkaloids generally generate offspring lower in PA than parent plants with a high alkaloid level. However plants totally free of alkaloids could not be generated through the crossing experiments. [ABSTRACT FROM PUBLISHER]