Physiological and Biochemical Controls Over Isoprene Emission from PlantsEPA Grant Number: U915539
Title: Physiological and Biochemical Controls Over Isoprene Emission from Plants
Investigators: Funk, Jennifer L.
Institution: The State University of New York at Stony Brook
EPA Project Officer: Packard, Benjamin H
Project Period: August 1, 1999 through August 1, 2002
Project Amount: $89,412
RFA: STAR Graduate Fellowships (1999) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology and Ecosystems
The goal of this research project is to identify physiological and biochemical factors contributing to variation in the basal rate of isoprene emission from plants.
Changes in plant carbon balance in response to environmental stress or resource availability are known to occur in many plant species and may result in potentially large fluctuations in basal emission rate. At the physiological level, populations of species that occur along natural nutrient and precipitation gradients will be sampled. Patterns of emission along gradients will be documented and screened for potential physiological influences on the rate of emission (e.g., photosynthetic capacity, growth rate). At the biochemical level, assessment will be conducted on the influence of three metabolic processes (photosynthesis, photorespiration, and respiration) on isoprene flux rate. If these processes significantly influence emission, the change in relative importance of each process, in response to environmental and physiological pressures, may contribute to the observed variation between individuals and populations.
Several studies have documented a positive correlation between leaf nitrogen concentration and isoprene emission. However, these studies were not conducted in the field where plants are subject to environmental fluctuations (e.g., light, temperature) and stress (e.g., herbivory, drought). In addition, over longer time periods, plants may show physiological or developmental acclimation or adaptation in response to nutrient or water availability. This type of knowledge is essential for predictive atmospheric modeling. The effect of water availability on isoprene flux currently is not well characterized. At the biochemical level, preliminary work suggests that in the absence of photosynthesis, photorespiration or respiration via the breakdown of starch pools may contribute carbon to the production of isoprene. The buildup of starch over the course of the day in some species may supply carbon for isoprene synthesis, resulting in diurnal patterns in the basal rate of isoprene emission.