INDUCED OLEORESIN BIOSYNTHESIS IN GRAND FIR AS A DEFENSE AGAINST BARKBEETLES

Grand fir (Abies grandis) saplings and derived cell cultures are usefu l systems for studying the regulation of defensive oleoresinosis in co nifers, a process involving both the constitutive accumulation of resi n (pitch) in specialized secretory structures and the induced producti on of monoterpene olefins (turpentine) and diterpene resin acids (rosi n) by nonspecialized cells at the site of injury. The pathways and enz ymes involved in monoterpene and diterpene resin acid biosynthesis are described, as are the coinduction kinetics following stem injury as d etermined by resin analysis, enzyme activity measurements, and immunob lotting. The effects of seasonal development, light deprivation, and w ater stress on constitutive and wound-induced oleoresinosis are report ed. Future efforts, including a PCR-based cloning strategy, to define signal transduction in the wound response and the resulting gene activ ation processes are delineated.