Regulation of source-sink development and leaf homeostasis in vascular plants that translocate monoterpenes as photo-assimilates in addition to sugars such as sucrose

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Vascular plants are complex eukaryotes that are photoautotrophs. They are desirable bio-reactors because they offer a sustainable source of organic compounds essential to our survival and well being. Plants have evolved multiple survival mechanisms for dealing with environmental stress. Their spatial and temporal, phenotype plasticity is unique in biology as plants regulate energy flow, initially solar energy trapped by the photosynthetic canopy into stable and mobile forms of reduced C, N and S. A primary source of photoassimilates is the leaf canopy, but, during vegetative and reproductive cycles contrary to popular belief other organs also contribute photoassimilates. If we are to exploit plants as bio-reactors for traditional (e.g., food, starch, sugars, amino acids, vitamins, etc) and novel bio-products (e.g., fuel, pharmaceuticals) our understanding of assimilate fluxes from source organs/tissues to developing sinks must improve. For example, the forms of reduced-C that are translocated via vascular phloem vary depending on the environmental stress and status of canopy development. Source-sink interactions determine productivity yet metabolite fluxes remain one of poorest understood plant processes. Selecting genes that can be targeted by either classical breeding protocols or using molecular bio-technologies to improve productivity of herbaceous and woody crops requires quantification of transport fluxes. In the Biotron facilities at Guelph we have engineered new analytical tools that are required to quantify phenotype plasticity at the organism, organ and organelle levels. In this project we will test new breeding lines, novel ecotypes and transgenics each with different genetic abilities to synthesize and transport large amounts of newly reduced C as monoterpenes (glucose esters such iridoids) as well as the better recognized sugar disaccaride, sucrose. Of particular interest as a model botanical family is the "newly" reclassified botanic family, the Plantaginaceae. These will be compared to selected members of the Leguminosea and the Brassicaeae as we have an opportunity to also test how targeted genetic modification of leaf shape and sink respiratory activity has altered efflux of reduced-C from leaves.