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THE genetic secrets of the world’s most popular crops have been revealed in two drafts of the rice genome, promising higher yields and better disease resistance.

In a publicly funded collaboration, a team led by Jun Yu of the Beijing Genomics Institute and the University of Washington Genome Center sequenced the indica subspecies of rice, one of the parents of a hybrid strain that is widely grown in China and throughout Asia. Meanwhile, Stephen Goff and his colleagues at the agribusiness company Syngenta sequenced the japonica subspecies, which is grown in Japan and other temperate regions.

While these draft sequences still contain many errors and gaps, the researchers say they will revolutionise plant science. “This will be a gold mine in plant improvement,” says Goff.

The rice genome is made up of 440 million DNA letters or base pairs and is packed with between 32,000 and 56,000 genes. It seems to contain at least as many functioning genes as the human genome, even though the entire human genome is seven times as large.

Scientists will use the sequence to pinpoint the genes responsible for desirable traits such as high yield and disease resistance. That knowledge could be used to genetically modify plants and pinpoint the best conventionally bred plants. “It will accelerate traditional breeding by allowing scientists to throw away all the junk fast,” says Goff.

Pamela Ronald, a plant pathologist at the University of California, Davis, says she has already used the Chinese sequence to help identify a disease resistance gene in rice. “Breeders have been using this trait for hundreds of years without knowing what it is,” she says. “This is such an explosion of sequence information, researchers are running around in a frenzy.”

In addition, the rice genome sequence will boost efforts to improve other crops because the arrangement of rice genes turns out to be very similar to that of other cereals such as barley, maize and wheat.

Already, Goff and others have used the rice genome to narrow down the possible locations of certain genes on maize chromosomes. Scientists already knew that an unknown gene on a chunk of chromosome 1 in one type of maize boosts the yield of crops. Rough mapping studies suggested that a similiar array and order of genes exists on rice chromosome 3. Goff looked at this region of the rice sequence and found 220 genes. They then compared these with databases of expressed genes in maize that matched, finding 100. So those genes must lie on the chunk of maize chromosome 1, and might include the elusive one that boosts yield.

The journal Science’s controversial decision to allow Syngenta to publish a paper while withholding their sequence from public databases means it is less available for other researchers. But Syngenta is now negotiating with the Japanese-led International Rice Genome Sequencing Project to include the company’s data in a more accurate rice genome sequence. The project will publish the sequence later this year, making all the data freely available.