Two genes for a sugar found mainly in microbes and insects make rice plants resistant to drought and other stresses, new greenhouse experiments show. If the engineered varieties do well in real rice paddies, they could greatly increase access to farm income and food in the developing world.
One of the main criticisms of agricultural biotechnology is that it mainly benefits wealthy agribusiness. The industry countered that criticism with "golden rice," engineered to express vitamin A, which is almost completely absent in conventional rice--and in the diets of many people in developing countries--contributing to blindness and slow growth in children. Critics say this rice would only be a stopgap, offering little improvement of the economic conditions that keep farmers poor and millions malnourished. Solving these deep-rooted problems with biotechnology requires varieties that grow in droughts and other marginal conditions. Engineering such hardy plants has proved more difficult than making rice golden.
Help now comes from trehalose, a sugar found in insects and microbes that somehow helps them handle cold, dry, or saline conditions. Researchers added two genes for trehalose, plus genetic on-off switches that ensured the genes would only do their business in certain tissues or under stress. Whereas previous attempts to boost trehalose production stunted plants, this new crop grew normally. And it suffered very little under stressful experimental conditions that killed nearly all conventional rice plants tested. Molecular biologist Ajay Garg and colleagues at Cornell University in Ithaca, New York, describe the varieties in a paper published online 27 November by the Proceedings of the National Academy of Sciences.
The varieties are "promising" and will enter field trials in the developing world next year, says Gary Toenniessen, agriculture director of the Rockefeller Foundation, a large philanthropic organization in New York City that is organizing the trials. "Drought tolerance is the trait that we give highest priority to, because we're targeting those 800 million people that have not benefited by the first green revolution," he says.
But just because the new plants pass for healthy in chilly upstate New York doesn't necessarily mean they'll grow well in more natural conditions, Toenniessen warns. "Rice plants grown in the greenhouse in Ithaca tend to be pretty sorry looking plants to begin with, so these plants may be already experiencing some physiological detriment that is being masked."