Terpenoid Defences in Spruce (Picea spp.)

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Species of spruce are among the most economically important trees for Canada's forest industry; they dominate many of the forest ecosystems across Canada, and are also of critical importance to forest economies in Asia and Europe. With environmental change, spruce and other conifers are increasingly challenged by outbreaks of insect pests and pathogens. Sustainable forest management requires advanced knowledge of trees' natural defence and resistance mechanisms. In hundreds of millions of years of co-evolution with pests and pathogens, conifers have evolved major chemical defences known as oleoresin (pitch). Oleoresin is a complex mixture of hundreds of specialized metabolites (terpenoids) formed in resin ducts or blisters. It consists mostly of diterpene resin acids (rosin) and volatile monoterpenes (turpentine). The chemical diversity of oleoresin is produced by genes and enzymes known as terpene synthases and cytochrome P450s. Conifers accumulate oleoresin as preformed or insect/pathogen-induced defences. Oleoresin and other chemicals provide durable protection for conifers against most potential pests or pathogens. While some highly destructive pests (e.g., weevils, bark beetles, budworms) can overwhelm or undermine tree defences, even in these systems unique tree resistance has been observed. For example, resistance against weevils was identified in select genotypes of Sitka spruce. My long-term research program on spruce defence against weevils established a field-defining system for a genomics-enabled, molecular characterization of oleoresin/terpenoid defences. My program delivers leading knowledge on natural tree defence mechanisms, which is being applied in collaboration with Canadian and international forest stewardship organizations for economic and ecological benefits. Beyond forestry, terpenoids are also enormously valuable for many bio-product industries (food, flavour, fragrance, bio-pesticides, pharmaceuticals) and as advanced biofuels. My program on terpenoid biochemistry delivers advanced knowledge and technology for applications in these industries. My program provides excellent training opportunities for undergraduate and graduate students, postdoctoral trainees, and technicians.