A new strain of GMO rice, with just a single altered gene, shows significant increases in yield per acre while reducing emission of methane, a greenhouse gas even more potent than carbon dioxide.

A single gene borrowed from barley has created the new strain that produces 43 percent more rice grain per plant while creating significantly less methane, researchers say.

With more than half of the world's population consuming rice as a dietary stable, rice paddies around the world constitute one of the largest human-linked sources of methane, with a greenhouse gas effect 20 times that of carbon dioxide.

It is estimated global rice production puts between 25 million and 100 million metric tons of methane into the atmosphere each year.

The researchers inserted a barley gene into the rice to cause it to store more carbon in the form of starch and sugar in its stems and grains, and less in its roots, they report in their study appearing in the journal Nature.

In rice paddies, the plants' roots leak carbon into the soil, where it is converted into methane by microbes. With less carbon in the roots, there is less raw material for the microbes to work on, the researchers explain.

In laboratory tests and field trials in China, methane emissions from the GMO rice were 0.3 percent compared with 10 percent produced by non-modified rice, they say.

"For three years of field trials it worked very well," says study senior author Chuanxin Sun of the Swedish University of Agricultural Sciences.

At the other end of the plants, the grain was starchier than conventional rice, increasing the food yield of the plants.

The dual benefits — higher yield with lower methane emissions — suggest "a tremendous opportunity for more-sustainable rice cultivation," Paul Bodelier, a microbial ecologist at the Netherlands Institute of Ecology, wrote in an essay accompanying the published Nature study.

It could be the better part of 10 years before this new strain of rice is widely available, the researchers caution, as more testing and more extensive field trials need to take place first.

It will also take years to selectively breed the genetic modification into a new variety of rice in sufficient volume to begin sending it to farmers for planting and harvesting, they say.

"Right now, of course, it's a GMO issue, and we cannot deliver this variety directly to farmers," says Sun. "We have to use traditional breeding methods and breed the new, society-acceptable variety for farmers."