Ultraviolet radiation drives methane emissions from terrestrial plant pectins

Abstract

Summary• 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.

A novel pathway of direct methane production and emission by eukaryotes including plants, animals and fungi: An overview

“…soil or plant water) and whether plants have their own mechanism(s) to produce CH 4 have been debated (Bruhn et al, 2012;Keppler et al, 2009;Nisbet et al, 2009). Evidence is now accumulating to indicate that plants can produce CH 4 even in the presence of oxygen (Bruggemann et al, 2009;Bruhn et al, 2009Bruhn et al, , 2014Cao et al, 2008;Fraser et al, 2015;Keppler et al, 2008;Lenhart et al, 2014;McLeod et al, 2008;Messenger et al, 2009;Mikkelsen et al, 2011;Reid, 2009, 2011;Sanhueza and Donoso, 2006;Sinha et al, 2007;Vigano et al, 2009Vigano et al, , 2008Wang et al, 2009aWang et al, , 2009bWang et al, , 2011aWatanabe et al, 2012;Wishkerman et al, 2011).…”

“…The impacts of UV radiation and heating on CH 4 emissions from detached leaves (Bruhn et al, 2009;Fraser et al, 2015;McLeod et al, 2008;Reid, 2009, 2011;Vigano et al, 2009Vigano et al, , 2008Wang et al, 2011b), intact plants and structural components (e.g. pectin, lignin, cellulose and leaf surface wax) (Bruhn et al, 2014;Keppler et al, 2008;McLeod et al, 2008;Messenger et al, 2009;Vigano et al, 2009Vigano et al, , 2008 have been extensively tested.…”

“…pectin, lignin, cellulose and leaf surface wax) (Bruhn et al, 2014;Keppler et al, 2008;McLeod et al, 2008;Messenger et al, 2009;Vigano et al, 2009Vigano et al, , 2008 have been extensively tested. The majority of studies reported substantial CH 4 emissions, while Bowling et al (2009) reported no evidence for substantial CH 4 emissions by a conifer forest under high UV radiation, to which a soil CH 4 sink might contribute.…”

Abiotic methanogenesis from organosulphur compounds under ambient conditions

“…It has been shown that CH 4 can be produced abiotically from plant material by exposing it to ultraviolet (UV) irradiation [15][16][17][18] . A reaction of reactive oxygen species (ROS) with methoxyl groups of pectic polysaccharides was suggested as a possible route to CH 4 formation under UV radiation 19 .…”

Methane emission by plant communities in an alpine meadow on the Qinghai-Tibetan Plateau: a new experimental study of alpine meadows and oat pasture

“…soil moisture and soil temperature) caused by environmental treatments, which may control CH 4 fluxes by regulating methanogenesis and oxidation processes (Pearce & Clymo 2001;Zhuang et al 2007). Therefore, plant-derived CH 4 emission is still questioned because limited evidence of the chemical mechanism has been identified to account for the process McLeod et al 2008;Vigano et al 2008;Messenger et al 2009). Using a closed, opaque chamber technique, we conducted an experiment with four treatments during the growing seasons of 2007 and 2008 to examine the hypothesis that abiotic (i.e.…”