Regulation of the Capacity for Isoprene Synthesis in Kudzu

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Sharkey Award AbstractThe overall goal of this research is to understand how the capacity for isoprene emission is regulated in Kudzu, an invasive weed which emits huge amounts of isoprene. Isoprene has a great impact on the environment because it contributes to the "near-ground" ozone formation and photochemical smog. Isoprene synthesis is a major biochemical pathway both in terms of the proportion of photosynthate converted to isoprene and in terms of the proportion of hydrocarbon entering the atmosphere. Studying isoprene emission is timely and important because isoprene biosynthesis is second only to photosynthetic carbon fixation in terms of carbon flux. Recent data indicate that in addition to short-term changes in rate, there is a longer-term (6-48 hours) change in the capacity for isoprene emission. In this research the molecular and biochemical basis of this longer-term regulation of the capacity for isoprene synthesis will be studied. Isoprene is made by the recently described deoxyxylulose phosphate (DXP) pathway. Two of the enzymes of this pathway have now been cloned in Arabidopsis even though Arabidopsis is not an isoprene emitting plant. These gene sequences will be used to make probes to measure message level for those enzymes in inductive and noninductive conditions. These proteins will also be expressed in E. coli so that antibodies can be made for use with western blots. Attempts will be made to clone isoprene synthase so that the regulation of this enzyme can also be studied. This information will be used to determine what regulation of the DXP pathway occurs when isoprene emission capacity changes and which changes likely regulate the capacity for isoprene emission.