INDUCED RESPONSES IN 3 ALKALOID-CONTAINING PLANT-SPECIES

In this paper we test three plant species for the inducibility of thei r alkaloid production. The plants were heavily damaged by cutting off 50% of their leaf surface using a pair of scissors. The cut-off leaf t ips were used as controls for possible diurnal fluctuations. After 3, 6, 12, 24 and 48 h, respectively, the leaf bases of the damaged plants were harvested and the alkaloid concentration was measured. In Seneci o jacobaea the pyrrolizidine alkaloid (Pa) concentration in damaged pl ants decreased within 6-12 h after damage. Within 24 h after damage th e Pa concentration of Cynoglossum officinale doubled compared to contr ol values. Indole alkaloid production in Catharanthus roseus was found not to be induced in this experiment. The responses are discussed in a functional context. We hypothesize that the nature of the response i s not a feature of the type of secondary metabolite, but is related to whether the plants are damaged mainly by generalist or by specialist herbivores.