New rice variety cuts methane emissions by 70%

The world’s emissions of methane, a potent greenhouse gas, are increasing rapidly, and rice farming produces around 12% of these emissions. After identifying the organic compounds rice plants secrete into soil, researchers have used that information to breed a new variety of rice that produces higher grain yield and helps reduce methane production by 70% (Mol. Plant 2025, DOI: 10.1016/j.molp.2025.01.008).

The roots of rice plants release carbohydrates and organic acids that microorganisms called methanogens devour, producing methane. But exactly which compounds instigate that process has been a mystery, says Anna Schnürer, a biotechnologist at the Swedish University of Agricultural Sciences.

To solve it, Schnürer, Chuanxin Sun, and their colleagues turned to a genetically modified (GM) rice strain they created a decade ago that sends less carbon to the roots, resulting in the release of less methane by the methanogens. “But we wanted to get away from GM,” Schnürer says.

So the researchers analyzed the chemical makeup of the soil at the low-methane GM strain’s root surfaces. Compared with a Japanese cultivar that has average emissions, the GM plants released less fumarate and more ethanol, inhibiting methanogens, they found. The team then screened about two dozen rice strains and found an heirloom varietal that also secretes low fumarate and high ethanol. Finally, the researchers crossbred the low-yield heirloom varietal with a high-yield commercial strain.

Three years of field trials in China show that the new strain emits 70% less methane than its commercial parent and produces almost twice the amount of grain per hectare compared with the global average.

Benjamin R. K. Runkle, who studies agricultural sustainability at the University of Arkansas, says that this work provides “a powerful combination” of both an understanding of the methane-production mechanism and a solution. Perhaps marrying this breeding strategy for low-methane rice with methane-reducing irrigation-management techniques could bring rice farming “closer to the goal of 100% reduction for true net-zero agriculture,” he says.