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The genus Oryza includes two domesticated “When we had figured that out, we distributed
species of rice, Asian and African, as well as those pieces to labs around the world to do the
22 wild relatives that span the globe. Rice sequencing of the rice genome.”
is genetically complex, with about 37,500 In 2004, at a meeting in Tucson, the team
genes — 7,500 more than the human genome. announced the completion of the finished
To successfully sequence the rice genome, sequence. In 2005, seven years after Wing started
Wing and his team developed “BAC libraries,” out, the work was published in Nature magazine.
frameworks constructed using bacterial For his leadership of the project, Wing received
artificial chromosomes, or BACs, that are clones the USDA’s highest recognition, the Secretary’s
containing very large DNA fragments and thus Honor Award.
help fill in gaps that are an inevitable part of “That was, and is, the highest quality genome
sequencing. that has ever been produced for a crop plant,”
“The genome consists of puzzles within Wing says. The reference genome for rice covers
puzzles,” Wing says. “And the BAC libraries are all the genes that the UA team sequenced with
the puzzle pieces.” Within each of those large 99.99 percent accuracy — that is, no more than
puzzle pieces are 150,000 combinations of the one error in every 10,000 of those nucleotide
letters AGCT, representing the four nucleotide bases. However, Wing says, “We were able to do
bases that make up all DNA. this for about 90 percent of the genome, and the
Seunghee Lee, assistant research “We made the pieces, and we knew the order rest was still missing.” Work on filling in the gaps
scientist, preparing a sample for of those pieces in the genome,” Wing continues. continues.
genome sequencing. Unlike the private companies studying rice
genomes, the IRGSP team immediately published
its findings in open databases so labs worldwide
could experiment with it. Now, the genome map
has become a crucial reference point to help
locate specific gene changes that create desirable
traits in rice plants and their offspring, called
lines.
The Wing team’s original sequence is the
research framework still in use by the IRGSP.
The research will also help improve other
cereal grasses like wheat, corn, oats, barley and
sorghum. In 2009, Wing’s team were leaders
in sequencing the genome of corn, which was
published in the prestigious journal Science.
They applied the same strategy they used for rice
on corn’s even larger genome.
As hybrids, the 210 rice plants on the roof of
the Sixth Street garage — the offspring of two
strong parent plants in China, selected by Wing’s
partners — are each a bit different. And, due to
hybrid vigor, they all are likely to be more robust
than the parents.
At about 100 days, each shoot will grow
its panicle — the stalk that bears flowers and
eventually rice kernels. Later, the plants will
move to fields that are part of new high-tech
facilities at the UA’s Maricopa Agricultural Center,
just off I-10 south of Phoenix. Robotic tractors,
drones and video monitors will watch each plant
and send data back for analysis.