Rice Genome Drafts Announced

Liz is a staff writer for Science.

BEIJING, TOKYO, AND WASHINGTON, D.C.--Two groups published their versions of the genome of rice today. One sequence comes from the rice consumed in China and most of Asia (the indica subspecies); the other is derived from the rice eaten in Japan and in temperate countries (the japonica subspecies). Heralded as a landmark achievement for agricultural sciences, these two efforts come from groups who are relative late-comers to rice sequencing. Yet they have pulled ahead of an international rice genome consortium.

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Currently, the genome of just one plant, a laboratory favorite called Arabidopsis, has been fully sequenced. But during the past decade, researchers have become ever more interested in sequencing rice--in part because it is a staple food for half the world's population and in part because it can help plant scientists find genes in other cereals with larger genomes. The rice genome is about 4 times the size of the Arabidopsis genome, but many times smaller than the genomes of either maize or wheat.

In the 5 April issue of Science, Yang Huanming of the Beijing Genomics Institute (BGI) and colleagues describe a draft sequence of the indica subspecies, and Steven Goff from the Switzerland-based agrobiotechnology giant Syngenta and his team report a similar achievement for japonica. Both were able to complete these versions at lightning speeds because they used a sequencing method called whole-genome shotgun. In this approach, all the DNA is cut into small bits that are sequenced and then pieced together with supercomputers.

Both sequences are works in progress: They contain many gaps and errors. But they provide the first detailed look at the genetic blueprint of rice. These genomes could have as many as 50,000, even 55,000 genes, Yang and Goff report--possibly more genes than humans have. These achievements make the international consortium, led by Takuji Sasaki of Japan's Rice Genome Research Program, fear that their funders will be less likely to support their drive to produce a sequence with no gaps. But the new data, which are publicly available, should prove a boon to the international consortium as it works to churn out a completed version of the rice genome by 2005.

For all those reasons, the unveiling of the rice genome, says Michael Freeling, a plant geneticist at the University of California, Berkeley, "is a big deal."

Related sites
Coverage of genome papers in Science
Indica paper
Japonica paper
Status of sequencing by the International Rice Genome Sequencing Project
Japan rice genome home page
General information about rice research

Posted in Biology