9633285 Fall Plants are a significant source of non-methane hydrocarbons to the atmosphere, yet the biochemical and physiological factors that influence these chemical emissions from terrestrial vegetation are not well understood. This project investigates the production and emission of 2-methyl-3-buten-2-ol (methylbutenol) in ponderosa pine and other pine species. Methylbutenol is a trace atmospheric constituent that has been measured in pine forests and is classified as an oxygenated hydrocarbons (oxHCs). The oxHCs are hypothesized as a potentially significant group of compounds that is important in the overall photochemistry of the Earth s planetary boudary layer and free troposphere. In addition to study of the biochemical mechanism of methylbutanol production in pine species, the project seeks to establish the relationship of this compound to the enzymatic formation of other isoprenoid chemicals synthesized by conifers. Results from the project will provide improved understanding of the biological and environmental factors that regulate the emission of natural oxHC to the atmosphere. This knowledge is necessary for developing predictive algorithms and models that will estimate fluxes of oxHCs in response to environmental conditions and to seasonal changes in plant metabolism. ***