title: Isoprene emission from plants: why and how.
abstract: BACKGROUND
  Some, but not all, plants emit isoprene. Emission of the related monoterpenes is more universal among plants, but the amount of isoprene emitted from plants dominates the biosphere-atmosphere hydrocarbon exchange.
  
  
  METHODS
  The emission of isoprene from plants affects atmospheric chemistry. Isoprene reacts very rapidly with hydroxyl radicals in the atmosphere making hydroperoxides that can enhance ozone formation. Aerosol formation in the atmosphere may also be influenced by biogenic isoprene. Plants that emit isoprene are better able to tolerate sunlight-induced rapid heating of leaves (heat flecks). They also tolerate ozone and other reactive oxygen species better than non-emitting plants. Expression of the isoprene synthase gene can account for control of isoprene emission capacity as leaves expand. The emission capacity of fully expanded leaves varies through the season but the biochemical control of capacity of mature leaves appears to be at several different points in isoprene metabolism.
  
  
  CONCLUSIONS
  The capacity for isoprene emission evolved many times in plants, probably as a mechanism for coping with heat flecks. It also confers tolerance of reactive oxygen species. It is an example of isoprenoids enhancing membrane function, although the mechanism is likely to be different from that of sterols. Understanding the regulation of isoprene emission is advancing rapidly now that the pathway that provides the substrate is known.
authors.affiliation: Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA. tsharkey@wisc.edu
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Sharkey
authors.forename: Amy E
authors.initials: AE
authors.lastname: Wiberley
authors.forename: Autumn R
authors.initials: AR
authors.lastname: Donohue
mesh_terms: D000064:Acclimatization; D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism; D001272:Atmosphere / Q000737:chemistry; D002070:Butadienes / Q000737:chemistry / Q000378:metabolism*; D045782:Hemiterpenes / Q000737:chemistry / Q000378:metabolism*; D006358:Hot Temperature; D008954:Models, Biological; D010126:Ozone / Q000737:chemistry; D010420:Pentanes / Q000737:chemistry / Q000378:metabolism*; D010788:Photosynthesis; D018521:Plant Physiological Phenomena; D010944:Plants / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; D017382:Reactive Oxygen Species; C005059:isoprene; D010126:Ozone; D019883:Alkyl and Aryl Transferases; C093854:isoprene synthase