Tougher rice strain made using genes from bacteria

Monday, December 9, 2002

WASHINGTON -- Biologists have boosted the rice plant's resistance to drought, cold and salt water by adding genes from a common bacteria. The hardy new rice strain is expected to thrive in fields and climates where the grain previously could not be grown, researchers say.

Scientists at Cornell University say they fused two genes from the E. coli bacterium and then inserted them into a common variety of rice to make the tough new strain.

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 that appeared in the Proceedings of the National Academy of Sciences. The genes are active only in the rice plant's stem and leaves and do not appear in the grain, he said.

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.

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 survive long periods of drought and resume vigorous growth once they get water again.

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.

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