Isoprene emission from trees is a significant source of hydrocarbon gases in the atmosphere. In this project the conditions which promote isoprene emission from oak trees will be investigated. This will contribute to our understanding of the atmosphere and our ability to predict changes in the atmosphere. Isoprene is released by plants to the atmosphere at a rate of 2% or more of the rate photosynthesis. This isoprene emission from plants is an important interface between the biosphere and the atmosphere; it is estimated that 350 X 1012 g of isoprene is released to the atmosphere each year. The PI proposes to determine what conditions accelerate the rate of isoprene emission from intact leaves and to determine what effects, if any, isoprene has on the physiology of plants. Specifically, he will test (1) the proposed relationship between isoprene emission and photorespiration, (2) the relationship between isoprene emission and the light reactions of photsynthesis, and (3) the relationship between isoprene emission and photosynthetic carbon metabolism. In addition experiments will be undertaken to assist in generating hypotheses. Experiments will be conducted with intact leaves. Isoprene formation is likely to involve glycolytic metabolism inside chloroplasts, which is also required for synthesis of tyrosine, tryptophan, leucine, isoleucine and valine, amino acids essential for human nutrition. Preliminary studies of how to begin biochemical studies of isoprene synthesis and glycolytic reactions inside chloroplasts will also be undertaken.
