Endogenous fumarate and ethanol dominate methane emission in rice paddies

Methane is the second-largest greenhouse gas after carbon dioxide, and its concentrations are increasing at a rate of more than ten times in the recent decade due to agriculture activities1. Rice paddies are considered a major source of anthropogenic CH4, estimated to account for 15-40% of the total emissions. Exudated organic from rice root provides abundance nutrition for methanogens survives in the anoxic environment. The mechanism of methane formation in rice paddies is still unknown even efforts to mitigate methane emission have been disbursed. Here we show that fumarate and ethanol are two dominant endogenous compounds from rice root secretion to adjust methane formation in rice paddies. SUSIBA2 low-methane-rice was used as a model plant and found its low methane property is derivative from lower fumarate and higher ethanol from the root. External addition of fumarate and ethanol in rice paddies resulting in significantly elevated and reduced methane emission, respectively. Treat paddies with ethanol or fumarate reductase inhibitor or screening low fumarate and high ethanol varieties have been approved in this paper as an effective strategy to produce environmental friendly rice.