Discovery delivers high starch content, virtually no methane emissions
Rice serves as the staple food for more than half of the world’s population, but it’s also the one of the largest manmade sources of atmospheric methane, a potent greenhouse gas. Now, with the addition of a single gene, rice can be cultivated to emit virtually no methane from its paddies during growth. It also packs much more of the plant’s desired properties, such as starch for a richer food source and biomass for energy production, according to a study in Nature.
With their warm, waterlogged soils, rice paddies contribute up to 17 percent of global methane emissions, the equivalent of about 100 million tons each year. While this represents a much smaller percentage of overall greenhouse gases than carbon dioxide, methane is about 20 times more effective at trapping heat. SUSIBA2 rice, as the new strain is dubbed, is the first high-starch, low-methane rice that could offer a significant and sustainable solution.
Researchers created SUSIBA2 rice by introducing a single gene from barley into common rice, resulting in a plant that can better feed its grains, stems and leaves while starving off methane-producing microbes in the soil.
The results, which appear in the July 30 print edition of Nature and online, represent a culmination of more than a decade of work by researchers in three countries, including Christer Jansson, director of plant sciences at the Department of Energy’s Pacific Northwest National Laboratory and EMSL, DOE’s Environmental Molecular Sciences Laboratory. Jansson and colleagues hypothesized the concept while at the Swedish University of Agricultural Sciences and carried out ongoing studies at the university and with colleagues at China’s Fujian Academy of Agricultural Sciences and Hunan Agricultural University.
“The need to increase starch content and lower methane emissions from rice production is widely recognized, but the ability to do both simultaneously has eluded researchers,” Jansson said. “As the world’s population grows, so will rice production. And as the Earth warms, so will rice paddies, resulting in even more methane emissions. It’s an issue that must be addressed.”
An increase in human-made carbon dioxide in the atmosphere could initiate a chain reaction between plants and microorganisms that would unsettle one of the largest carbon reservoirs on the planet — soil.
Researchers based at Princeton University report in the journal Nature Climate Change that the carbon in soil — which contains twice the amount of carbon in all plants and Earth’s atmosphere combined — could become increasingly volatile as people add more carbon dioxide to the atmosphere, largely because of increased plant growth. The researchers developed the first computer model to show at a global scale the complex interaction between carbon, plants and soil, which includes numerous bacteria, fungi, minerals and carbon compounds that respond in complex ways to temperature, moisture and the carbon that plants contribute to soil.
Although a greenhouse gas and pollutant, carbon dioxide also supports plant growth. As trees and other vegetation flourish in a carbon dioxide-rich future, their roots could stimulate microbial activity in soil that in turn accelerates the decomposition of soil carbon and its release into the atmosphere as carbon dioxide, the researchers found.
This effect counters current key projections regarding Earth’s future carbon cycle, particularly that greater plant growth could offset carbon dioxide emissions as flora take up more of the gas, said first author Benjamin Sulman, who conducted the modeling work as a postdoctoral researcher at the Princeton Environmental Institute.
“You should not count on getting more carbon storage in the soil just because tree growth is increasing,” said Sulman, who is now a postdoctoral researcher at Indiana University.
Meat grown using tissue engineering techniques, so-called ‘cultured meat’, would generate up to 96% lower greenhouse gas emissions than conventionally produced meat, according to a new study.
The analysis, carried out by scientists from Oxford University and the University of Amsterdam, also estimates that cultured meat would require 7-45% less energy to produce than the same volume of pork, sheep or beef. It would require more energy to produce than poultry but only a fraction of the land area and water needed to rear chickens.
A report of the team’s research is published in the journal Environmental Science & Technology.
‘What our study found was that the environmental impacts of cultured meat could be substantially lower than those of meat produced in the conventional way,’ said Hanna Tuomisto of Oxford University’s Wildlife Conservation Research Unit, who led the research. ‘Cultured meat could potentially be produced with up to 96% lower greenhouse gas emissions, 45% less energy, 99% lower land use, and 96% lower water use than conventional meat.’