The Jacobaea hybrid system has been proved to be a good tool to study the interaction between PA variation and herbivore resistance. Based on this hybrid system, we have explored how the biotic and... Show moreThe Jacobaea hybrid system has been proved to be a good tool to study the interaction between PA variation and herbivore resistance. Based on this hybrid system, we have explored how the biotic and abiotic factors influence the PA diversity. All the herbivore tests were integrated to draw the general conclusion that the selection pressures from different herbivores contribute to the diversity in PA composition and that generalist and specialist herbivores exert a divergent selection pressure on PA concentrations. The PAs showed seasonal variation within each genotype and the relative differences between genotypes remained constant over time, which was the first study to report the seasonal variation of SMs. The application of MeJA can lead to a shift in PA composition and primary metabolites. Importantly the shift in metabolite diversity induced by MeJA application can conversely affect the feeding of chewing herbivores and cell-content feeders. However, SA application did not lead to significant changes in PAs and the metabolite profile changes detected by NMR rendered J. aquatica more resistance to piercing-sucking herbivore thrips, showing that PAs did not affect thrips resistance. Several metabolites detected by NMR were found to be correlated with resistance and susceptibility to thrips F. occidentalis. Show less
