The genome is the second largest to have been sequenced to date (smaller only than the human genome) and the first for a crop plant. The project took only 18 months and has produced a genome map that the companies say is "99.5% complete". The publicly funded effort to sequence the rice genome's 430 million DNA bases, led by Japan, is three years away from completion.

Myriad, which is based in Salt Lake City, says that its proprietary high-throughput sequencing facilities enabled it to complete the genome six months ahead of schedule — earning a $3 million bonus from Syngenta as part of a $33 million deal.

The companies' success has raised worries about the impact on poorer countries that rely on rice as a staple food crop. But Syngenta says it will provide information and technology that can produce crop improvements for subsistence farm-related research "without royalties or technology fees".

The company says that it will make its rice genome data — derived from the Nipponbare variety — available to researchers through "research contracts".

Given the apparent — and apparently unexpected — similarity between the rice genome and those of various cereals, the rice sequence is expected to aid the study of crops such as wheat, corn and barley.

Syngenta's announcement has shaken partners in the publicly funded International Rice Genome Sequencing Project (IRGSP), which has sequenced 5% of the genome to completion and an additional 25% to the level of quality achieved by Syngenta's sequence.

Takuji Sasaki, principal investigator of the IRGSP, says the project's partners will meet next week and discuss Syngenta's results. He says the claim of 99.5% completeness will be difficult to verify "as the company won't show its cards". But he worries that politicians may nonetheless consider the job done and pull the plug on the publicly funded project. This would be unwise, he says, as the IRGSP's sequence will be both more accurate than Syngenta's and freely available.