Unravelling the effects of blue light on aerobic methane emissions from canola.

It is now well documented that plants produce methane (CH4) under aerobic conditions. However, the nature of methane production in plants and all the potential precursors and environmental factors that can be involved in the process are not fully understood. Earlier studies have suggested several chemical compounds, including the amino acid methionine, as precursors of aerobic methane in plants, but none have explored other amino acids as potential precursors or blue light as a driving force of methane emission. We examined the effects of blue light, and the promoter or inhibitor of endogenous ethylene on methane and ethylene emissions, amino acids, and some plant physiological parameters in canola (Brassica napus). Plants were grown under four light conditions: no supplemental blue light, and low, medium, or high blue light, and exposed to three chemical treatments: no chemical application, ethylene promoter (kinetin), or ethylene inhibitor (silver nitrate). Regardless of chemical treatment, blue light significantly increased methane emission, which was accompanied by decreased plant biomass, gas exchange, and flavonoids, but by increased wax, and most amino acids. This study revealed that blue light drives aerobic methane emission from plants by releasing of methyl group from a number of amino acids, and that the methane production in plants may have several pathways.