November 20, 2009

Scientists Unveil Maize Genome

A team of scientists on Thursday revealed the fully completed sequence of the maize genome.

Writing in the journal Science, researchers at the Genome Sequencing Center (GSC) at Washington University in St. Louis, Mo., along with teams from the University of Arizona, Iowa State University and Cold Spring Harbor Laboratory in New York, uncovered the complete genome sequence in maize.

The map shows the order of genes along each of maize's 10 chromosomes and the physical distance between those genes, researchers said.

The sequence spans 2.3 billion DNA base-pairs and contains some 32,500 genes, or about one-third more than the human genome, they said. The maize genome contains 2.3 billion nucleotide sequences, about 85 percent of which are repetitive.

"Both the sequence itself and the annotations are a landmark," said Dr Doreen Ware, a co-principal investigator with the CSHL lab.

"Having the complete genome in hand will make it easier to breed new varieties of corn that produce higher yields or are more tolerant to extreme heat, drought, or other conditions," said senior author Richard Wilson, director of Washington University's Genome Center.

"Seed companies and maize geneticists will pounce on this data to find their favorite genes," he said. "Now they'll know exactly where those genes are."

"An understanding of the combination of genetic factors that result in superior performance will influence future breeding programs, which will produce higher yield or improved quality crops to meet the demands of an energy and nutrition hungry world," said Brad Barbazuk, a UF assistant professor in biology and member of the UF Genetics Institute.

Barbazuk and colleagues used the newly released DNA sequence of the corn strain known as B73 to compare it to Mo17. They found that at least 180 genes appear in B73 that aren't found in Mo17.

"The genomes of two corn strains are much more different than we would have thought," Springer said. "What struck us is how many major changes there are between two individuals of the same species."

Scientists said this diversity could account for the reason certain hybrids are far superior.

"Hybrid offspring are probably benefiting from obtaining the genes unique to each inbred parent in addition to unique combinations of favorable alleles." Barbazuk said.

It took 150 researchers four years to complete the reference genome for one of the world's most important crops and the most valuable plant to the US. The project cost $29.5 million and was funded by the National Science Foundation and the US departments of agriculture and energy.

Corn makes up $47 billion in annual value in the US. The US is the source of 44 percent of the world's corn.


On the Net: