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. Ofall thesignificant essential oil-producing families, Myrtaceae isthe onlyone for which there is no molecular information on terpene biosynthesis. Here we summarise available knowledge on terpene biosynthesis and its relevancetotheMyrtaceaetoprovideafoundationforecologicalandgeneticstudiesofchemicaldiversity.Thereareseveral stepsintheterpenebiosynthesispathwaythathavepotentialforinfluencingtheoilyield,profileandcompositionofleafoils inMyrtaceae.ThebiochemicalstepsthatinfluenceoilyieldinMyrtaceaeprobablyoccurinthestepsofthepathwayleading up to the synthesis of the terpene backbone. Qualitative differences in oil profiles are more likely to be due to variation in terpenesynthasesandterpene-modifyingenzymes.Mostoftheinformationonmolecularvariationinterpenebiosynthesisis basedontheanalysisofartificiallyderivedmutantsbutAustralianMyrtaceaecanprovideexamplesofthesamemechanisms in an ecological context.