Mass Spectrometry in the Australian Landscape

Mass spectrometry has played a crucial role in developing our understanding of the complex chemical ecology of the Australian bush and plantation forests. Pheromones used for communication between individuals of the same species, and the chemical defences of eucalypts against herbivory and fungal decay are part of this broad picture. On the other side of an evolutionary battle, herbivorous marsupials have evolved unique and complex metabolic pathways to counter their otherwise toxic essential oil and phenolic rich diet. A wide range of organic chemical classes from relatively simple (but often novel) aliphatic compounds through to hydrolysable tannins, condensed tannins, flavonoids, formylated phloroglucinol compounds (FPCs), and highly oxidized terpenes are part of this complex network. As well as being fundamental to the assignment of known organic compounds, mass spectrometry has enabled the determination of the structures or partial structures of many new compounds in these groups. Examples include highly oxidized terpene metabolites (including the major koala metabolites), the discovery of the mechanism of feeding deterrence conferred by the presence of high FPC levels in eucalypt leaves, the discovery of many new types of FPCs in eucalypt leaves and wood, an increased understanding of eucalypt tannin chemistry, and highly complex possum cloacal pheromone secretions. This presentation will describe some of these examples of our research on Australian flora and fauna.