A HIGH-QUALITY version of the rice genome is now freely available on the Internet.
Rice was the second plant to be sequenced after the lab workhorse, the fast-growing cress Arabidopsis thaliana. But the first versions were created by private companies and were only available to researchers prepared to sign restrictive licence agreements. The journal Science came under fire last year for publishing a paper on the rice genome assembled by Syngenta of Switzerland even though the company would not make the actual sequence freely available.
Now the International Rice Genome Sequencing Project, a 10-nation publicly funded effort, has unveiled the most complete draft yet 鈥� and it鈥檚 available to all. Japan did most of the sequencing, followed by the US and China. And after an agreement was reached with the company, the group was able to include Syngenta鈥檚 data, as well as that of The Institute for Genomic Research in Maryland.
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鈥淩ice is the most important food crop in the world, and feeds half the population,鈥� said Rod Wing of the University of Arizona, head of the US鈥檚 contribution, at a ceremony to unveil the draft sequence in Washington DC last month. 鈥淚t鈥檚 imperative we learn as much as possible about it.鈥�
His sentiments are echoed in Tokyo by Takuji Sasaki of Japan鈥檚 National Institute of Agrobiological Sciences, the leader of the international effort. Although a finished genome is still a few years off, the draft is helping scientists to identify rice genes and their functions. Genes for resistance to diseases such as rice blast have already been found, he told New 杏吧原创.
Identifying rice genes will help breeders create more productive, nutritious or stress-resistant strains, through conventional breeding or genetic engineering. 鈥淲e鈥檝e been waiting for this and now it鈥檚 here, it鈥檚 fantastic,鈥� says Mike Gale of Britain鈥檚 John Innes Centre in Norfolk.
The draft is of the subspecies Oryza sativa japonica, grown in many countries around the world. A rough draft of the genome of Oryza sativa indica, the other major rice subspecies, was published in Science by a Chinese team in April 2002. However, it doesn鈥檛 yet have a genome 鈥渕ap鈥� allowing all the sequences to be put into place, unlike the japonica sequence. But an analysis by Gale suggests the two genomes differ by fewer than 16 letters per 5000.
The rice genome is also similar to that of other cereals such as wheat and barley, Gale says. That means that work done on one cereal can easily be applied to others. For example, after the mutation responsible for a dwarf form of wheat was discovered, a Japanese team produced a dwarf form of rice by creating the mutation in the equivalent gene.
The 12 rice chromosomes have around 400 million letters compared with our own 3.1 billion. Yet rice has between 40,000 and 60,000 genes, double our meagre 30,000 or so.