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Rice Genome Deciphered, Could Help Ease Global Hunger - 2002-04-05


In an achievement that promises to help ease global hunger, two papers published Thursday in the journal "Science" describe the genetic blueprints of two varieties of rice. Experts say the development stands to improve a crop that feeds more than half the world's people. It could have other benefits as well.

Rice is the food staple for approximately 67 percent of the world's population. Like many crops, the grain is subject to the whims of nature, including draught, disease, and gnawing insects.

That may change, if not immediately, then in the not-too-distant future, thanks to the work of two independent teams of researchers working on the rice genome.

Genes are the chemical codes in the cells of all living things. Among other things, they determine how well an animal or plant resists disease and what it looks like.

In published papers, a U.S.-Swiss team and a Chinese team of investigators describe how they deciphered most of the genetic instructions for the two most common varieties of rice, the short grain japonica rice favored in Japan and the indica rice subspecies most eaten in China.

"It is just astounding how many novelties we observe and how many unexpected discoveries we make rather easily once this information comes forward, says Jeff Bennetzen, a Professor of genetics at Purdue University in Hammond, Indiana. "The major discoveries that they made ... had to do with the particular genes involved. And [they] discovered that rice has a large number of genes relative to other organisms that have been studied; more genes in fact than are detected in humans."

It appears rice and humans have about two-thirds of their genes in common. The remaining one-third of rice genes is devoted to functions such as photosynthesis.

The benefits of having the rice genome sequenced include cutting the time it takes to zero-in on hardy rice strains and breeding them with other insect or draught resistant strains of rice. Or it may even be possible to more readily grow rice in places where it is not indigenous, such as Africa.

Another possibility, according to Purdue University's Jeff Bennetzen, is plumbing the rice genome for information for his area of study - corn. "Rice and wheat and barley and corn all have very similar genes... They have only diverged from a common ancestor from 50 to 70-million years," he says.

Rice was chosen for sequencing, as opposed to other cereal grains, because its genome is much smaller than other cereal grain.

Pamela Ronald is a molecular biologist at the University of California who says hardier rice is good for the environment. "There is a problem with applying lots of pesticides and high amounts of hydrogen fertilizer," she says. "So, if we can take the information that we see in the genome and use that to more rapidly develop varieties that will resist disease, for example not having to spray anything, that would be a very big success."

It took less than a year to identify the sequences of the two rice varieties. Scientists must now plot the genes on a map so others can make use of work. That is expected to take a year or more.

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