International researchers crack genetic code of rice

Breakthrough could lead to hardy strains with more nutrients

April 05, 2002|By BOSTON GLOBE

In a scientific breakthrough with vast nutritional and commercial implications, researchers laboring on three continents have decoded the genetic profile of rice, a discovery that could help increase the nutrients in one of the world's most basic foods.

The findings, reported in today's edition of Science, could one day allow farmers to grow golden rice that has been genetically altered to contain extra vitamins, without having to splice in genes from other plants.

The genetic blueprints for two strains of rice are also expected to help scientists unravel the genetic secrets of other dietary staples, including wheat and corn, advances that could yield corn bearing just the right genetic composition to thrive in cold, damp climates.

Leading scientists predicted that the draft genetic blueprints for rice could prove even more important, at least in the short term, than the human genome.

"Rice is the world's calorie champion: More people depend on and consume rice calories than from any other crop," said Donald Kennedy, editor-in-chief of Science, which published the human genome findings two years ago.

"I would guess that over the next 20 years, the rice genome will make more of a difference to global health than the human genome. It's an extraordinary landmark."

The completion of the genetic blueprint for rice, the first plant to be genetically decoded, was accomplished by four teams with lightning speed.

It turned out that rice was fairly simple to catalog. The research being released today shows that rice consists of about 45,000 genes embedded in 420 million base pairs, the rungs of the DNA ladder. The corn genome is six times as large and the wheat genome is 40 times as large as the rice genome.

But the cereals have enough genetic similarity that scientists can use the findings from the rice genetic inventory to understand a constellation of cereals with greater nutritional value and less susceptibility to disease.

"In that sense, this is a Rosetta stone; it's the key that unlocks all the cereal crops," said Gane Ka-Shu Wong, a University of Washington genome biologist involved with sequencing the indica variety of rice, the world's most commonly consumed.

With the sketching out of the genetic architecture of indica and another variety, japonica, agricultural scientists and farmers will be able to work faster and smarter in developing new crop strains. In the past, seed varieties would be mixed and matched until the desired combination was hit upon, an often tedious, inexact process.

The drafts being released today are more than 99 percent complete, and the rice gene sequences are expected to be completed in 12 to 18 months.

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