Making plant methane formation visible-Insights from application of 13C-labeled dimethyl sulfoxide

Individual and interactive effects of temperature and blue light on canola growth, lignin biosynthesis and methane emissions

It is now well documented that plants produce methane (CH4) under aerobic conditions. However, the mechanisms of methane production in plants, its potential precursors, and the factors that are involved in the process are not fully understood. Few studies have considered the effects of blue light on methane emissions from plants; however, the combined effects of temperature and blue light have not been studied. We studied the effects of two temperature regimes (22/18 °C and 28/24 °C; 16 h light/8 h dark), and three blue light levels (0, 4, and 8 mW cm-2; 400-500 nm) on the growth, lignin, and methane emissions of canola (Brassica napus). Plants were grown under experimental conditions for three weeks, and then methane, monolignols and other plant traits, including growth, biomass, growth index, photosynthesis, chlorophyll fluorescence, and photosynthetic pigments, were measured. Blue light significantly increased methane emissions, stem height, and growth rate, but decreased stem diameter, leaf number and area, biomass, specific leaf mass, leaf area ratio, shoot/root mass ratio, photosynthetic pigments, sinapyl alcohol, and coniferyl aldehyde. Higher temperature significantly decreased stem diameter, non-photochemical quenching, sinapyl alcohol, and coniferyl aldehyde. Methane emission was negatively correlated with plant dry mass, leaf area per plant, and maximum quantum yield of photosystem II. However, no significant relationships were found between methane and monolignols. In conclusion, plants emitted more methane under stress conditions; however, further studies are required to understand the potential precursors of methane and the mechanism of its synthesis in plants.

Aerobic methane production in Scots pine shoots is independent of drought or photosynthesis

Shoot-level emissions of aerobically produced methane (CH4) may be an overlooked source of tree-derived CH4, but insufficient understanding of the interactions between their environmental and physiological drivers still prevents the reliable upscaling of canopy CH4 fluxes. We utilised a novel automated chamber system to continuously measure CH4 fluxes from the shoots of Pinus sylvestris (Scots pine) saplings under drought to investigate how canopy CH4 fluxes respond to the drought-induced alterations in their physiological processes and to isolate the shoot-level production of CH4 from soil-derived transport and photosynthesis. We found that aerobic CH4 emissions are not affected by the drought-induced stress, changes in physiological processes, or decrease in photosynthesis. Instead, these emissions vary on short temporal scales with environmental drivers such as temperature, suggesting that they result from abiotic degradation of plant compounds. Our study shows that aerobic CH4 emissions from foliage are distinct from photosynthesis-related processes. Thus, instead of photosynthesis rates, it is more reliable to construct regional and global estimates for the aerobic CH4 emission based on regional differences in foliage biomass and climate, also accounting for short-term variations of weather variables such as air temperature and solar radiation.

ROS-driven cellular methane formation: Potential implications for health sciences

Recently it has been proposed that methane might be produced by all living organisms via a mechanism driven by reactive oxygen species that arise through the metabolic activity of cells. Here, we summarise details of this novel reaction pathway and discuss its potential significance for clinical and health sciences. In particular, we highlight the role of oxidative stress in cellular methane formation. As several recent studies also demonstrated the anti-inflammatory potential for exogenous methane-based approaches in mammalians, this article addresses the intriguing question if ROS-driven methane formation has a general physiological role and associated diagnostic potential.