Sesquiterpene lactones and herbivore resistance

Stereochemical variation is common in plant secondary metabolites, but its importance in mediating plant–herbivore interactions has received little attention. Ahern and Whitney  use common garden experiments with common cocklebur, Xanthium strumarium (Asteraceae), to examine relationships between stereochemical variation in sesquiterpene lactones, herbivore damage and plant fitness. They find that the stereochemistry of sesquiterpene lactone ring junctions helps explain variation in plant herbivore resistance, in turn influencing plant fitness. Their results indicate that subtle differences in stereochemistry may be a major, yet under-appreciated, determinant of the protective role of secondary metabolites.