VOC formation in plants & bacteria

The Fall lab is investigating biochemical aspects of volatile organic compound (VOC) formation in plants and bacteria.  The "VOC tree" below illustrates the large variety of VOCs formed in plants, and points out that many different tissues,cellular compartments, and biochemical pathways are involved in the biosynthesis of VOCs.

The following links provide more information about our current research regarding
these VOCs:

 isoprene
 methylbutenol
 leaf wound VOCs.

 senescence


Why are we interested in biogenic VOCs? 
Biogenic VOCs are a key part of one
of the major environmental problems of our time ? sustainability of the oxidative power of the atmosphere in the face of human alterations to the World’s forests and climate. What is the oxidative power of the atmosphere and why is it important to the biosphere?  The oxidative power of the atmosphere, in simple terms, is defined as the atmospheric capacity to form hydroxyl radical (OH), otherwise known as the "detergent of the atmosphere."  The daily photochemical production of OH controls the oxidation of major atmospheric gases, such as
methane, carbon monoxide, and reduced nitrogen and sulfur gases.  Thus, the
oxidative power of the atmosphere affects the lifetimes of atmospheric components of the major biogeochemical cycles.The strong oxidative power of the
Earth’s atmosphere is a direct result of biological activity. Normal functioning of the OH system is closely linked with a simple biological molecule, isoprene (2-methyl-1,3-butadiene) and other reactive biogenic VOCs.In the case of isoprene, emissions from the World’s forests are huge, estimated at >500 million tons per year, comparable to global release of the greenhouse gas, methane.  In the presence of sunlight isoprene can trigger OHformation or OH destruction, depending on the levels of nitrogen oxides(NOx).  Thus the oxidative balance of the atmosphere is strongly linked to biospheric processes, andbio chemical reactions in plants may be responsible for the formation of ozone plumes or OH holes in forested regions of the Earth.  It is important to understand biochemical and physiological controls on the formation and release of these VOCs to the atmosphere, especially given man-made changes in global CO2 levels and temperature, NOx emissions, and planting of large isoprene-emitting agriforests.

Reference.  R. Fall (1999) Biogenic emissions of VOCs from higher plants. In: Reactive
Hydrocarbons in the Atmosphere, C.N. Hewitt (ed.), pp. 43-96, Academic Press,
San Diego.

 
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