title: Ultraviolet radiation drives methane emissions from terrestrial plant pectins.
abstract: Recent studies demonstrating an in situ formation of methane (CH(4)) within foliage and separate observations that soil-derived CH(4) can be released from the stems of trees have continued the debate about the role of vegetation in CH(4) emissions to the atmosphere. Here, a study of the role of ultraviolet (UV) radiation in the formation of CH(4) and other trace gases from plant pectins in vitro and from leaves of tobacco (Nicotiana tabacum) in planta is reported. Plant pectins were investigated for CH(4 )production under UV irradiation before and after de-methylesterification and with and without the singlet oxygen scavenger 1,4-diazabicyclo[2.2.2]octane (DABCO). Leaves of tobacco were also investigated under UV irradiation and following leaf infiltration with the singlet oxygen generator rose bengal or the bacterial pathogen Pseudomonas syringae. Results demonstrated production of CH(4), ethane and ethylene from pectins and from tobacco leaves following all treatments, that methyl-ester groups of pectin are a source of CH(4), and that reactive oxygen species (ROS) arising from environmental stresses have a potential role in mechanisms of CH(4) formation. Rates of CH(4 )production were lower than those previously reported for intact plants in sunlight but the results clearly show that foliage can emit CH(4) under aerobic conditions.
authors.affiliation: Institute of Atmospheric and Environmental Sciences, School of GeoSciences, The University of Edinburgh, Crew Building, West Mains Road, Edinburgh EH9 3JN, UK.
authors.forename: Andy R
authors.initials: AR
authors.lastname: McLeod
authors.affiliation: Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, Daniel Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Fry
authors.affiliation: Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, Daniel Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Loake
authors.affiliation: Institute of Atmospheric and Environmental Sciences, School of GeoSciences, The University of Edinburgh, Crew Building, West Mains Road, Edinburgh EH9 3JN, UK.|Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, Daniel Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Messenger
authors.affiliation: Institute of Atmospheric and Environmental Sciences, School of GeoSciences, The University of Edinburgh, Crew Building, West Mains Road, Edinburgh EH9 3JN, UK.
authors.forename: David S
authors.initials: DS
authors.lastname: Reay
authors.affiliation: Institute of Atmospheric and Environmental Sciences, School of GeoSciences, The University of Edinburgh, Crew Building, West Mains Road, Edinburgh EH9 3JN, UK.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Smith
authors.affiliation: Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, Daniel Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK.
authors.forename: Byung-Wook
authors.initials: BW
authors.lastname: Yun
mesh_terms: D004980:Ethane / Q000378:metabolism; D005030:Ethylenes / Q000096:biosynthesis; D008697:Methane / Q000096:biosynthesis*; D010368:Pectins / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013472:Sunlight; D014026:Nicotiana / Q000378:metabolism / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D005030:Ethylenes; D017382:Reactive Oxygen Species; D010368:Pectins; C036216:ethylene; D004980:Ethane; D008697:Methane