Reduced rice paddy methane emission through dual compound mechanism in novel cultivars

Methane is the second most abundant greenhouse gas after carbon dioxide and its concentrations have risen tenfold in the past decade due to agricultural activity1. Rice paddies are considered a major source of anthropogenic methane, however strategies to mitigate methane emission in rice paddies is not yet successful despite considerable efforts being made. Methane production is caused by microbial communities feeding on organic exudates from the rice root, and regulation of the dominant secretions has been suggested as leading way to put an end to the methane emission from rice paddies. Here, we introduced a new system to reduce methane emission in rice paddies based on the discovery that fumarate and ethanol are two specific rice-orchestrated compounds that determine the levels of methane emission from rice paddies. Moreover, stable low-fumarate high-ethanol secretion lines have been successively bred through hybrid breeding and shown to cut around 70% of methane emission in paddies as compared to control. Approaches to block fumarate reductase or increase ethanol level, were furthermore employed as cultivation managements and resulted in a reduction in methane emissions of around 60%, calculated from two-year four-site field work. All results highlight the application of our findings to largely mitigate influences of rice cultivation on global climate.