Missing methane emissions from leaves of terrestrial plants

Abstract

The controversial claim that attached leaves of terrestrial plants emit CH 4 aerobically remains to be corroborated. Here, we report CH 4 fluxes and CO 2 exchange rates for leaves of the C 4 species Zea mays using a high-accuracy traceable online analytical system. In contrast to earlier results for Z. mays, our measurements provide no evidence for substantial aerobic CH 4 emissions from photosynthesizing leaves illuminated with photosynthetically active radiation (k 5 400-700 nm), or from dark-respiring leaves. Preliminary measurements with the same system indicated a similar lack of aerobic CH 4 emissions in the light or dark from leaves of the C 3 species Nicotiana tabacum. These findings are supported by independent high-precision 13 C-labeling studies that also failed to confirm substantial aerobic CH 4 emissions from plants. Nevertheless, we are not able to exclude the possibility that CH 4 emissions from plants may be linked to nonenzymatic processes with an action spectrum lying outside the wavelength range for photosynthesis.

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

“…Several studies have reported opposite results that no measurable CH 4 release from plants was detected (Beerling et al, 2008;Bowling et al, 2009;Dueck et al, 2007;Kirschbaum and Walcroft, 2008;Nisbet et al, 2009;Smeets et al, 2009;Takahashi et al, 2012). One potential explanation for the absence of CH 4 emissions is that the CH 4 produced was consumed by endophytic methanotrophs.…”

Effect of UV radiation and temperature on the emission of methane from plant biomass and structural components

“…The first follow-up study (Dueck et al, 2007) did not confirm the findings: No 13 CH 4 emissions were found from plants, which were grown in a 13 CO 2 atmosphere and should thus have produced 13 CH 4 only. Beerling et al (2008) similarly reported no CH 4 emissions from a C3 and a C4 species but suggested a possible role of nonenzymatic processes with an action spectrum outside the photosynthetically-active range. Nevertheless, to the best of our knowledge there is no scenario other than direct emissions from the plant matter that can explain the (natural abundance) isotope signatures observed in the earlier experiments by Keppler et al (2006).…”

Physical injury stimulates aerobic methane emissions from terrestrial plants

“…Some studies (Dueck et al, 2007;Beerling et al, 2008;Kirschbaum and Walcroff, 2008;Nisbet et al, 2009) observed no substantial aerobic CH 4 emission from plants. However, six independent studies McLeod et al, 2008;Vigano et al, 2008;Wang et al, 2008;Brüggemann et al, 2009;Messenger et al, 2009) did detect CH 4 emission from plant tissues/compounds under aerobic conditions in the laboratory.…”