NIU scientists help refine genetic map of rice

by Tom Parisi

Two Northern Illinois University researchers are part of a team of scientists announcing that they have completed detailed gene mapping of a rice chromosome.

Long Mao and Mitrick Johns, both professors in the NIU Department of Biological Sciences, participated in the sequencing of chromosome 10. With 23 million base pairs of DNA, it is believed to be the smallest of the dozen chromosomes that make up the rice genome.

“This is the first completed map of this chromosome,” Mao said. “Its sequencing is another key step toward unraveling the genetic makeup of the world’s most important food crop.”

Led by Rod A. Wing of the University of Arizona, more than 100 scientists from universities and research institutions across the country participated in the chromosome’s gene mapping. The scientists describe their findings in the June 6 issue of the prestigious journal, Science.

The rice genome presents a potential genetic blueprint for other cereal crop plants.

Last year, separate consortiums of scientists published draft genome sequences for the indica and japonic varieties of rice. But only now are scientists decoding precise sequences for each of the 12 chromosomes. The detailed information could lead to breakthroughs in the production of enhanced food crops with greater yields and improved disease resistance.

“Chromosome 10, in particular, appears to be a major player in disease resistance,” Johns said. “We know this through comparisons to genes identified as playing a role in the resistance of disease in other plants. Our ability to understand what allows the plant to fight those diseases will allow us to manipulate the genetics to make improved crops.”

Chromosome 10 contains 3,471 genes. An earlier draft sequence had estimated less than half that number, illustrating the importance of the more detailed mapping.

“We now have a much clearer picture,” Mao said. “We know the structure of the chromosome, where the genes are located and how they correlate to important genetic traits.”

About one-third of the world’s inhabitants depend on rice for more than 50 percent of their caloric intake. Rice also is important in genetic terms because it is closely related to cereal crops such as wheat, corn and barley. Mao said the rice genome is much smaller than other cereals, making it a logical choice for analysis. The wheat genome, for example, is 40 times bigger than the rice genome.

The NIU Foundation, the Graduate School and the Plant Molecular Biology Center contributed funding toward the gene-mapping project.

6-9-03