XVI International Botanical Congess

Bark beetle infestation and associated fungal infection represent the most serious disease problem in North American forests. Conifers, including pines, firs and spruces, defend themselves against such attack by the production of oleoresin, a complex mixture of turpentine (monoterpenes and sesquiterpenes) and rosin (diterpenoid resin acids), designed to poison invaders and seal wound sites. The multi-layered, and highly co-evolved, chemical ecological relationships between conifer host, beetle pest, and beetle predator are first described. This is followed by a brief review of oleoresin biochemistry, with emphasis on the unusual catalysts responsible and their corresponding genes. The organization and regulation of the induced defense response is then illustrated using grand fir as a model system. The presentation concludes with a discussion of the possibilities for the molecular redesign of oleoresin composition to improve tree resistance, for example, by chemically disguising the host, or by altering the levels of repellents, pheromone precursors, or predator and parasite attractants.