This project exploits the plant trichome (leaf hair) gland, a specialized plant tissue
that produces and exudes copious end-product secondary biochemicals that are involved in
pest and disease resistance. This aggregate of cells suspended on a stalk above leaf and
stem surfaces produces massive exudates that have species-specific, simple diterpene
chemical profiles. Dr. Wagner will study metabolic regulation that controls carbon flow in
glands into specific diterpenes by introducing genes that encode enzymes which have
potential to divert carbon flow into non-endogenous but closely related
diterpenes. Gene
suppression experiments will also be used to metabolically engineer endogenous diterpene
metabolism and study the plasticity of diterpene biosynthesis in glands. These efforts
will be based on a well characterized gland system, available genes from this system, and
the recent demonstration of diterpene metabolic engineering in this system using a gene
suppression approach. In addition to being a system amenable to studying metabolic
regulation of diterpene metabolism, plant trichome glands that produce copious diterpenes
have potential to serve as "factories" for renewable and efficient production of
pharmaceutically active diterpenes that are currently available only from
environmentally-sensitive sources (e.g., those from soft corals). An understanding of the
metabolic regulation and plasticity of diterpene metabolism in trichome gland cells is
needed if this high production cell type is to realize its potential as a renewable
resource for producing valuable diterpenes and other secondary metabolites. In addition, a
better understanding of secondary metabolism in trichome glands can also aid in efforts to
increase natural disease resistance in crop plants. Trichome gland-based resistance of
primitive tomato, potato, and other plants has often been lost during breeding of
cultivated varieties to optimize yield, etc. These properties might be re-established
through metabolic engineering of trichome glands. Broader aspects of the project include
training and learning at the postdoctoral, graduate, undergraduate and technician levels.
Under-represented groups will be included in the project. The project will enhance the
infrastructure of research and education by developing the diterpene trichome gland system
as a tool for studying metabolic regulation and engineering, and establishing a
partnership between G. Wagner's terrestrial plant biology laboratory and W. Fenical's
(collaborator) marine animal biology laboratory, both having a common interest in
diterpene metabolism. A second, broader impact is the potential for the project to produce
information that can be disseminated through commercial channels to provide new
opportunities for sustainable agriculture. Our long term goal is to develop the trichome
gland system as a renewable, economical system for producing terpenes and other products,
including pharmacologically active marine diterpenes.
