Making plant methane formation visible—Insights from application of (13)C‐labeled dimethyl sulfoxide

Methane (CH(4)) formation by vegetation has been studied intensively over the last 15 years. However, reported CH(4) emissions vary by several orders of magnitude, thus making global estimates difficult. Moreover, the mechanism(s) for CH(4) formation by plants is (are) largely unknown. Here, we introduce a new approach for making CH(4) formation by plants clearly visible. By application of (13)C‐labeled dimethyl sulfoxide (DMSO) onto the leaves of tobacco plants (Nicotiana tabacum) and Chinese silver grass (Miscanthus sinensis) the effect of light and dark conditions on CH(4) formation of this pathway was examined by monitoring stable carbon isotope ratios of headspace CH(4) (δ(13)C‐CH(4) values). Both plant species showed increasing headspace δ(13)C‐CH(4) values while exposed to light. Higher light intensities increased CH(4) formation rates in N. tabacum but decreased rates for M. sinensis. In the dark no formation of CH(4) could be detected for N. tabacum, while M. sinensis still produced ~50% of CH(4) compared to that during light exposure. Our findings suggest that CH(4) formation is clearly dependent on light conditions and plant species and thus indicate that DMSO is a potential precursor of vegetative CH(4). The novel isotope approach has great potential to investigate, at high temporal resolution, physiological, and environmental factors that control pathway‐specific CH(4) emissions from plants.