Biologists say they've created a strain of rice that is more resistant to drought, cold and salt water, which could allow farmers to grow it in places with conditions that would be impossible for ordinary rice.
The development is being watched closely by agricultural experts, who have said that the world's rice production is going to have to increase by 190 million tons over the next 25 years.
According to the International Rice Commission, rice has fed a greater number of people for a longer period of time than any other food crop. The commission points out that the implications of a stable and adquate rice crop extend into every area of many countries' well-being and economic development, while failures of rice crops - in Asia, for example - have many times triggered famine and political instability.
Scientists at Cornell University, writing about their breakthrough in the Proceedings of the National Academy of Sciences, say they were able to produce the new, hardier strain of rice by fusing two sugar-making genes from the E. coli bacterium and then placing them into a common variety of rice.
The genes added a sugar, called trehalose, to the rice plant and made it more hardy, said Ajay K. Garg, a Cornell researcher and first author of the study. The genes are active only in the rice plant's stem and leaves and do not appear in the grain, he said.
Garg said trehalose is found in small amounts in many types of plants, insects, fungi and bacteria, but it is a major component in the growth of plants that can survive long periods of drought and then spring back vigorously once water has been restored.
The addition of the trehalose had the same effect on the rice plant, he said.
"We can withhold water for 10 days and the plant seems to die," said Garg. "But when water is added, it is restored."
Normal rice plants would be beyond recovery after 10 days without water, he said.
Garg said experiments also showed the transgenic rice plant is about twice as resistant to salt water and will withstand temperatures about 10 degrees lower than other rice plants.
This means farmers will be able to grow rice in fields where it once was impossible due to salty or dry soils, or because of chilly climates, Garg said.
Laboratory studies also showed the new rice strain is up to 15 percent more efficient in photosynthesis, the process of converting sunlight and nutrients into plant growth. This suggests the strain will have a higher grain yield than ordinary rice plants, said Garg.
The researchers have now grown the new rice strain through five generations and the stress-resistant genes were maintained and active in each succeeding generation, said Garg.
Several more years of experiments, including growing crops in large scale test fields, must be performed before the new rice strain can be certified for general agricultural use, he said.
The Cornell researchers are patenting the new rice strain, but Garg said they will then release it for general use.
"We want to put this into the public domain so people everywhere can use it," he said.
Garg said his team is now turning its attention to corn, wheat, millet and soybean plants. He said researchers are experimenting to see if adding trehalose genes will make those grain crops more resistant to drought and other stresses.