A molecular perspective on terpene variation in Australian Myrtaceae

The terpenoid-dominated essential oils in Australian Myrtaceae mediate many ecological interactions and are important industrially. Of all the significant essential oil-producing families, Myrtaceae is the only one for which there is no molecular information on terpene biosynthesis. Here we summarise available knowledge on terpene biosynthesis and its relevance to the Myrtaceae to provide a foundation for ecological and genetic studies of chemical diversity. There are several steps in the terpene biosynthesis pathway that have potential for influencing the oil yield, profile and composition of leaf oils in Myrtaceae. The biochemical steps that influence oil yield in Myrtaceae probably occur in the steps of the pathway leading up to the synthesis of the terpene backbone. Qualitative differences in oil profiles are more likely to be due to variation in terpene synthases and terpene-modifying enzymes. Most of the information on molecular variation in terpene biosynthesis is based on the analysis of artificially derived mutants but Australian Myrtaceae can provide examples of the same mechanisms in an ecological context.