The genetic secrets of the world鈥檚 most popular crops are about to be revealed thanks to the publication of two drafts of the genome of rice.
In a publicly-funded effort, Jun Yu of the Beijing Genomics Institute and the University of Washington Genome Center and his colleagues sequenced the indica subspecies of rice, one half of a hybrid strain that is widely grown in China and throughout Asia.
Stephen Goff and his colleagues at the agribusiness company Syngenta sequenced the japonica subspecies, grown in Japan and other temperate regions.
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While these draft sequences still contain many errors and gaps, the researchers say they will revolutionise plant science. 鈥淭his will be a gold mine in plant improvement,鈥� says Goff.
Information explosion
快猫短视频s will use the sequence to pinpoint the genes responsible for desirable traits such as high yield and disease resistance. Goff says that knowledge could be used to genetically modify plants. 鈥淚t will also accelerate traditional breeding by allowing scientists to throw away all the junk fast.鈥�
In addition, the rice genome sequence will boost efforts to improve other crops because the arrangement of rice genes turns out to be so similar to that of other cereals such as barley, maize and wheat. 鈥淭his is such an explosion of sequence information, researchers are running around in a frenzy,鈥� says Pamela Ronald, a plant pathologist at the University of California, Davis.
The rice genome turns out to contain 440 million DNA letters or base pairs and is packed with between 32,000 to 56,000 genes. In contrast, the human genome is seven times larger, but may contain the same number, or even fewer, genes.
Trait tracking
To demonstrate how the rice genome can be used to track down elusive genetic traits in other crops, Goff鈥檚 team investigated QTL 21, a region of maize chromosome 1 which boosts the yield of the plant. Work by Goff and others have demonstrated a very similar array and order of genes exist on rice chromosome 3.
The new rice sequence reveals 220 genes in this region. By searching databases for similar genes, the researchers found 100 unmapped maize genes that could account for the boost in yield. 鈥淭hat is a much better starting point than 40,000 unknown genes,鈥� says Goff.
Ronald says she has already used the Chinese sequence to help identify a disease resistance gene in rice. 鈥淏reeders have been using this trait for hundreds of years without knowing what it is,鈥� she says.
厂肠颈别苍肠别鈥檚 controversial decision to allow Syngenta鈥檚 to publish in the journal 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鈥檚 data in more accurate rice genome sequence the IRGSP will publish later in 2002. All that data will be freely available.
Journal reference: Science (vol 296, p 79, p 92)