Abstract
Many conifer species synthesize copious amounts of oleoresin, composed mainly of monoterpenes and diterpene resin acids in addition to smaller amounts of sesquiterpenes. A diverse array of hundreds of chemical compounds which are initially produced by terpene synthases (TPSs) and further modified by cytochrome P450 monooxygenases (P450), is important in conifer defence against herbivores and pathogens. Our recent gene discovery and phylogenetic cluster analysis for spruce and pine P450s revealed that the CYP720 subfamily consists of over 30 P450s. Here, we report new results from the biochemical characterization of Sitka spruce CYP720B4. To investigate the biochemical functions, we expressed CYP720B4 and the Sitka spruce NADPH-P450 reductase in E.coli, respectively. In vitro assay results show that this P450 catalyze three oxidation steps at the C-18 position of abietadiene to form abietic acid, and also oxidize other diterpenoid olefins (resins) to the corresponding resin acids.
