Following the hypothesis that secondary metabolism evolved under selection pressure of a competitive and continuously changing environment, chemical diversification is one of the essential needs in secondary metsbolism to cope with and adapt to an ever changing environment. Both long-distance translocation and vacuoIar storage require specific membrane carriers.
PAs are well known defence compounds.
This is evidenced by the fact that a number of insects from diverse taxa have evolved adaptations not only to overcome PA mediated defence but aIso sequester and utiIise PAs against predators. This enzyme must have been evolved in the course of the coevolutionary adaptation process of PA storing insects to PA produclng plants.