Pamela Ronald of the University of California, Davis and her colleagues first identified a stretch of DNA--dubbed Submersion 1--linked to immersion survival. Narrowing their focus to one gene in this stretch that proved highly variable in various rice strains--Sub1A-1--the researchers found that it conferred the ability to withstand high waters for up to two weeks and then renew growth once the waters subsided. "Each year millions of small farmers in the poorest areas of the world lose their entire crops to flooding," Ronald says. "These newly developed rice varieties will help ensure a more dependable food supply."
Current annual rice crop losses exceed $1 billion, particularly because the highest yielding varieties do not withstand flooding at all. But by introducing the gene into strains that previously lacked it, the researchers improved tolerance for submersion without diminishing yield levels and grain quality. Already, submergence-tolerant rice is being developed for Bangladesh, Laos and India--all subjects of recent, devastating floods. The research appears in today's Nature.