Terpene synthases from Australian Tea Tree (Melaleuca alternifolia)

Melaleuca alternifolia is an evergreen, Australian native tree species commonly referred to as Tea Tree. It is the major source of Australian tea tree oil, an economically important product with anti-microbial properties. The anti-microbial properties of the oil are primarily attributed to the monoterpene terpinen-4-ol. Terpinen-4-ol is produced by the skeletal rearrangement of sabinene hydrates both in vivo and in vitro. The oil also contains significant levels of the monoterpenes 1,8 cineole, terpinolene and a- and g- terpinene along with some sesquiterpenes. Amino acid sequence comparison of other terpene synthases isolated from a diverse range of plants revealed regions of high or absolute conservation. Degenerate primers were designed to these regions and used to generate oligonucleotide probes for monoterpene synthases. These probes were then used to screen a cDNA library derived from M. alternifolia flush growth, the primary site of monoterpene biosynthesis. As a parallel approach to elucidating the biochemistry of terpene biosynthesis in M. alternifolia, cell free extracts with sabinene hydrate synthase activity have also been generated.